JP2014086221A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery excellent in cycle endurance characteristics of a battery in high temperatures and having high energy density, in a lithium secondary battery designed on a high-voltage specification.SOLUTION: A nonaqueous electrolyte secondary battery includes: a nonaqueous electrolyte containing a lithium salt and a nonaqueous solvent dissolving the lithium salt; and a negative electrode and a positive electrode which are capable of absorbing and desorbing lithium ions. The nonaqueous electrolyte contains a fluorinated cyclic carbonate, and the upper limit operating potential of the positive electrode is 4.75 V or higher and 4.90 V or lower relative to Li/Li.

Description

  The present invention relates to a secondary battery including a non-aqueous electrolyte, and more specifically, the electrolyte contains a specific fluorinated carbonate, and the upper limit operating potential of the positive electrode is 4.75 V or more and 4.90 V or less. The present invention relates to a non-aqueous electrolyte secondary battery.

  Non-aqueous electrolyte secondary batteries such as lithium secondary batteries are widely used as power sources for so-called portable electronic devices such as mobile phones and notebook computers, to in-vehicle power sources for automobiles and large power sources for stationary applications. It is being put into practical use. However, with the recent high performance of electronic devices and the application to in-vehicle power supplies for driving and large power supplies for stationary applications, the demand for applied secondary batteries is increasing, and the high performance of the battery characteristics of secondary batteries is increasing. For example, it is required to achieve high levels of improvement in capacity, high temperature storage characteristics, cycle characteristics, and the like.

In particular, mobile devices and the like are becoming more advanced and multifunctional, and further enhancement of the energy density of lithium secondary batteries, which are the power sources, is strongly desired. In addition, there is a demand for a battery with a good balance of performance, such as safety, cost competitiveness, and longevity (especially at high temperatures), and lithium secondary batteries that can meet these needs are being actively developed. .
Under such circumstances, various proposals have been made to improve the energy density of the lithium secondary battery. Several means are conceivable for improving the energy density of the battery, and one of them is to raise the upper limit operating potential of the positive electrode and increase the open circuit voltage between the battery terminals of the battery. When a conventional general lithium secondary battery is charged, the open circuit voltage between the battery terminals at the end of charging is usually 4.2 V or less, that is, the upper limit operating potential of the positive electrode is 4.25 V. Therefore, in order to obtain a higher energy density than before, development of a lithium secondary battery whose positive electrode upper limit potential exceeds 4.25 V has been attempted. However, the higher the voltage, the more unavoidable side reactions are caused by the decomposition of the electrolyte in the positive electrode, and the cycle deterioration becomes extremely large. Therefore, the conventional lithium secondary battery in which the upper limit operating potential of the positive electrode exceeds 4.25V. Was not practical.

  In response to the desire to increase the open circuit voltage between the battery terminals at the end of charging, Patent Document 1 discloses a technique using an electrolyte solution composed of a non-aqueous solvent containing 50% by volume or more of γ-butyrolactone and a lithium salt. Proposed. Patent Document 1 describes that the above-described technique increases the capacity of the secondary battery and further improves the cycle characteristics and the like. However, the maximum circuit voltage between the battery terminals is 4.40V with respect to the graphite negative electrode, that is, only the example in which the upper limit operating potential of the positive electrode is 4.45V is illustrated.

  In addition, in conventional battery systems, by using a cyclic carbonate having a double bond, represented by vinylene carbonate and its derivatives, and vinyl ethylene carbonate derivatives, a good quality film is formed on the negative electrode surface, and the battery is stored. Patent Documents 2 and 3 disclose that characteristics and cycle characteristics are improved. However, in high-voltage battery systems where the upper limit potential of the positive electrode is high, if the battery is left at a high temperature or subjected to continuous charge / discharge cycles, the unsaturated cyclic carbonate or its derivative is oxidized and decomposed on the positive electrode to generate carbon dioxide. If carbon dioxide gas is generated in such a use environment, the battery itself may become unusable due to, for example, the safety valve of the battery operating or the battery expanding.

Furthermore, the oxidative decomposition of unsaturated cyclic carbonate on the positive electrode causes a problem of generation of a solid decomposition product in addition to the generation of carbon dioxide gas. Generation of such a solid decomposition product causes clogging of the electrode layer and the separator to inhibit the movement of lithium ions, or the solid decomposition product remains on the surface of the electrode active material and causes the lithium ion insertion / release reaction. Inhibit. As a result, for example, the charge / discharge capacity may gradually decrease during the continuous charge / discharge cycle, the charge / discharge capacity may decrease from the initial stage after storage at a high temperature of the battery or after the continuous charge / discharge cycle, or the load characteristics may deteriorate.

Therefore, as a development policy of a non-aqueous electrolyte solution that can stably operate in a high-voltage battery system, a method of improving oxidation resistance by fluorinating a conventional non-aqueous solvent has been studied.
For example, Patent Document 4 describes a graphite negative electrode-based 5.0 V class battery using a non-aqueous electrolytic solution in which 4,5-difluoroethylene carbonate obtained by fluorinating cyclic carbonate and ethylene carbonate is mixed. The effect of suppressing gas generation has been confirmed. However, regarding the battery characteristics, only the improvement in the initial capacity and the initial load characteristics has been confirmed, and the durability battery characteristics remain unclear.
In addition, electrolytes composed only of such high-viscosity solvents usually not only significantly deteriorate battery characteristics at low temperatures with non-aqueous electrolytes, but also are difficult to handle during injection, and the separator has very high wettability. However, there are still problems such as low.

  In Patent Documents 5 and 6, as a technique for improving battery characteristics such as cycle characteristics in a 4.2 to 4.3 V battery based on a graphite negative electrode, that is, a battery having a positive electrode potential of about 4.35 V, ethylene carbonate, 4 -Techniques relating to mixed non-aqueous electrolytes of fluoroethylene carbonate and fluorinated chain carbonate are described. However, in the present technology, in addition to this, for the purpose of improving the rate characteristics of the battery and reducing the viscosity of the electrolyte, it is essential to contain a carboxylic acid ester or a non-fluorinated chain carbonate, and the positive electrode potential is There is a concern about these oxidative decompositions in the region of 4.35V or more. The patent document does not disclose means for solving these problems.

Patent Document 7 describes a non-aqueous electrolytic solution in which ethylene carbonate, 4-fluoroethylene carbonate, and fluorinated chain carbonate are mixed for the purpose of suppressing gas generation with little cycle deterioration. However, in this patent document as well as the above-mentioned known document, only a technique relating to a battery using a low potential region of a specific LiCoO ₂ positive electrode is disclosed in the examples. This patent document does not disclose a technique for solving high temperature storage under a high voltage such that the upper limit operating potential of the positive electrode exceeds 4.35 V, and durability deterioration during cycling.

  Patent Document 8 discloses a technology for suppressing capacity deterioration using a mixed solvent of a cyclic carbonate, a fluorinated cyclic carbonate, and a fluorinated chain carbonate for a 4.3 V battery using a silicon negative electrode. However, graphite negative electrodes exemplified as non-silicon negative electrodes only show significant capacity deterioration due to reductive decomposition of fluorinated cyclic carbonate, and this patent document discloses a technique for suppressing deterioration of silicon negative electrodes. Only the features are disclosed. Further, the patent document does not mention or suggest a high voltage battery exceeding 4.3V.

  In Patent Document 9, in a battery of 4.35 V or higher, a mixed solvent of cyclic carbonate, fluorinated cyclic carbonate, and fluorinated chain carbonate is used, and charge / discharge cycle characteristics at high temperature and low swelling due to high-temperature storage gas are reduced. Techniques to do this are disclosed. However, what is actually confirmed is the result at 4.4 V, and the characteristics in the region of higher voltage are not known.

JP 2003-272704 A JP-A-8-45545 JP-A-4-87156 JP 2003-168480 A International Publication No. 2010/004952 International Publication No. 2010/013739 International Publication No. 2007/043526 JP 2007-294433 A JP 2007-250415 A

  The present invention solves the above-mentioned various problems that occur when trying to achieve the performance required for a secondary battery in recent years, and in particular, a low amount of generated gas in a battery having a high positive electrode upper limit operating potential. Another object of the present invention is to provide a non-aqueous electrolyte secondary battery excellent in high-temperature cycle durability.

  As a result of intensive studies to solve the above problems, the inventors have used a specific solvent as the non-aqueous electrolyte used in the non-aqueous electrolyte battery, so that the upper limit potential of the positive electrode is 4.75V. As described above, in the high voltage design battery of 4.85 V or less, it has been found that a non-aqueous electrolyte secondary battery excellent in durability characteristics such as a low gas generation amount and a high temperature cycle can be realized, and the present invention has been completed.

That is, the gist of the present invention is as follows.
a) a non-aqueous electrolyte comprising a lithium salt and a non-aqueous solvent for dissolving the lithium salt, a negative electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte secondary battery comprising a positive electrode, wherein the non-aqueous electrolyte The electrolytic solution contains a fluorinated cyclic carbonate represented by the following general formula (1), and the upper limit operating potential of the positive electrode is 4.75 V or more and 4.90 V or less on the basis of Li / Li ^+. Non-aqueous electrolyte secondary battery.

(In general formula (1), R ₁ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different from each other.)
b) The non-aqueous electrolyte secondary battery according to a), wherein the fluorinated cyclic carbonate represented by the general formula (1) is 4-fluoroethylene carbonate or 4,5-difluoroethylene carbonate. .
c) The non-aqueous electrolyte secondary battery according to a) or b), wherein the non-aqueous electrolyte contains a fluorinated chain carbonate represented by the following general formula (2).

(In General Formula (2), R ₂ represents a hydrocarbon group containing at least one fluorine which may have a substituent, and R ₃ represents a hydrocarbon group which may have a substituent, and they are the same as each other. Or different.)
d) The nonaqueous electrolyte secondary battery according to c), wherein the fluorinated chain carbonate represented by the general formula (2) is trifluoroethyl methyl carbonate.
e) The non-aqueous electrolyte secondary battery according to any one of a) to d), wherein the non-aqueous electrolyte contains a cyclic carbonate represented by the following general formula (3).

(In general formula (3), R ₄ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different from each other.)
f) The non-aqueous electrolyte secondary battery according to e), wherein the cyclic carbonate represented by the general formula (3) is ethylene carbonate or propylene carbonate.
g) The non-aqueous electrolyte contains a fluorinated cyclic carbonate represented by the following general formula (1) and a fluorinated chain carbonate represented by the following general formula (2), or the following general formula ( 1) containing a fluorinated cyclic carbonate represented by the following general formula (2) and a cyclic carbonate represented by the following general formula (3), and a total blend of these carbonates The nonaqueous electrolyte secondary battery according to any one of c) to f), wherein the amount is 50% by volume or more in the nonaqueous solvent.
h) The nonaqueous electrolyte secondary battery according to g), wherein the blending amount of the fluorinated chain carbonate represented by the general formula (2) is 40% by volume or more in the nonaqueous solvent. .
i) A non-aqueous electrolyte solution comprising a lithium salt and a non-aqueous solvent for dissolving the lithium salt, a negative electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte secondary battery comprising a positive electrode, wherein the non-aqueous electrolyte The electrolytic solution contains a fluorinated chain carbonate represented by the following general formula (2), and the upper limit operating potential of the positive electrode is 4.75 V or more and 4.90 V or less on the basis of Li / Li ^+. Non-aqueous electrolyte secondary battery.

(In General Formula (2), R ₂ represents a hydrocarbon group containing at least one fluorine which may have a substituent, and R ₃ represents a hydrocarbon group which may have a substituent, and they are the same as each other. Or different.)
j) The non-aqueous electrolyte secondary battery according to i), wherein the fluorinated chain carbonate represented by the general formula (2) is trifluoroethyl methyl carbonate.
k) The non-aqueous electrolyte secondary battery according to i) or j), wherein the non-aqueous electrolyte contains a cyclic carbonate represented by the following general formula (3).

(In general formula (3), R ₄ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different from each other.)
l) The non-aqueous electrolyte secondary battery according to k), wherein the cyclic carbonate represented by the general formula (3) is ethylene carbonate or propylene carbonate.
m) The non-aqueous electrolyte contains a fluorinated chain carbonate represented by the following general formula (2) and a cyclic carbonate represented by the following general formula (3), and the total amount of these carbonates is The non-aqueous electrolyte secondary battery according to any one of i) to l), wherein the non-aqueous solvent is 50% by volume or more.
n) The nonaqueous electrolyte secondary battery according to m), wherein the blending amount of the fluorinated chain carbonate represented by the general formula (2) is 40% by volume or more in the nonaqueous solvent. .
o) Any one of a) to n), wherein the positive electrode contains at least one selected from the group consisting of lithium transition metal compounds represented by the following general formulas (i) to (iii): The non-aqueous electrolyte secondary battery according to one.

Li [Li _a M _x Mn _2−x−a ] O _{4 + δ} (i)
(In formula (i), 0 ≦ a ≦ 0.3, 0.4 <x <1.1, −0.5 <δ <0.5 is satisfied, and M is Ni, Cr, Fe, Co and Cu. Represents at least one of transition metals selected from
Li _x M1 _y M2 _z O _2-δ (ii)
(In formula (ii), 1 ≦ x ≦ 1.3, 0 ≦ y ≦ 1, 0 ≦ z ≦ 0.3, −0.1 ≦ δ ≦ 0.
1, M1 represents Ni, Co and / or Mn, M2 represents Fe, Cr, V, Ti, Cu, Ga, Bi, Sn, B, P, Zn, Mg, Ge, Nb, W, It represents at least one element selected from Ta, Be, Al, Ca, Sc and Zr. )
αLi ₂ MO _3. (1-α) LiM′O ₂ (iii)
(In the formula (iii), 0 <α <1 is satisfied, M is at least one metal element having an average oxidation number of +4, and M ′ is at least one metal element having an average oxidation number of +3. Represents.)
p) The non-aqueous electrolyte secondary battery according to any one of a) to o), wherein the negative electrode contains at least one negative electrode active material composed of graphite particles.

One means for improving the energy density of a lithium secondary battery is to raise the open circuit voltage between battery terminals as described above. In particular, for a device that operates at a high voltage, the use of a high voltage battery having a high open circuit voltage between battery terminals is a particularly effective means. As a method for raising the open circuit voltage between the battery terminals, it is conceivable to raise the positive electrode upper limit operating potential. Become. In the present invention, the fluorinated cyclic carbonate represented by the general formula (1) is introduced into the non-aqueous electrolytic solution, and the upper limit operating potential of the positive electrode is controlled to 4.75 V or more and 4.90 V or less, thereby being stabilized. The present invention has been completed by finding a non-aqueous electrolyte secondary battery that is operable and has little cycle deterioration.

  According to the present invention, it is possible to provide a non-aqueous electrolyte battery that is excellent in cycle durability characteristics of a battery at a high temperature and has a high energy density, particularly in a lithium secondary battery designed to have a high voltage specification.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments, and can be arbitrarily modified and implemented.
The non-aqueous electrolyte secondary battery of the present invention can take a known structure, and typically, a negative electrode and a positive electrode capable of occluding and releasing ions (for example, lithium ions), a non-aqueous electrolyte, A separator is provided.

1. Non-aqueous electrolyte 1-1. Non-aqueous solvent 1-1-1. Solvent The nonaqueous electrolytic solution of the present invention contains a fluorinated cyclic carbonate represented by the following general formula (1) or a fluorinated chain carbonate represented by the following general formula (2). In addition, the fluorinated carbonates represented by the following general formulas (1) and (2) may be used in combination, and the non-fluorinated chain carbonates represented by the following general formula (3) are preferably or simultaneously contained. Is done. In addition, as the non-aqueous solvent, non-fluorinated chain carbonates, cyclic and chain carboxylic acid esters, ether compounds, sulfone compounds, and the like may be used.
<Fluorinated cyclic carbonate represented by the general formula (1)>

(In general formula (1), R ₁ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different from each other.)
Examples of the fluorinated cyclic carbonate represented by the general formula (1) include derivatives of cyclic carbonates having an alkylene group having 2 to 6 carbon atoms.
Specific examples of the fluorinated cyclic carbonate include ethylene carbonate or a fluorinated product of ethylene carbonate substituted with an alkyl group (for example, an alkyl group having 1 to 4 carbon atoms).

The number of fluorine atoms in the fluorinated cyclic carbonate is not particularly limited as long as it is 1 or more, but those having 1 to 8 fluorine atoms are preferable.
Specifically, monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4-fluoro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4- Fluoro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethyl Le ethylene carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate.

  Among them, from the group consisting of monofluoroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4- (fluoromethyl) -ethylene carbonate At least one selected is preferable in terms of providing high ionic conductivity and suitably forming an interface protective film, and more preferably at least one selected from fluoroethylene carbonate and 4,5-difluoroethylene carbonate. In particular, fluoroethylene carbonate is preferred because it makes it easy to keep the storage characteristics and cycle characteristics of the non-aqueous electrolyte secondary battery in a favorable range.

The fluorinated cyclic carbonate represented by the general formula (1) may be used alone or in combination of two or more in any combination and ratio.
The blending amount of the fluorinated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. However, in 100% by volume of the non-aqueous solvent, preferably 1% by volume or more, more preferably 2% by volume or more. , Most preferably 4% by volume or more, preferably 40% by volume or less, more preferably 30% by volume or less, and most preferably 15% by volume or less. Within this range, the non-aqueous electrolyte secondary battery tends to exhibit a sufficient cycle characteristic improvement effect, and avoids a decrease in discharge capacity maintenance rate due to a decrease in high-temperature storage characteristics or an increase in the amount of gas generated. Cheap.
<Fluorinated chain carbonate represented by the general formula (2)>

(In General Formula (2), R ₂ represents a hydrocarbon group containing at least one fluorine which may have a substituent, and R ₃ represents a hydrocarbon group which may have a substituent, and they are the same as each other. Or different.)
The fluorinated chain carbonate represented by the general formula (2) is preferably one having 3 to 7 carbon atoms. The number of fluorine atoms contained in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, they may be bonded to the same carbon or may be bonded to different carbons. Examples of the fluorinated chain carbonate include a fluorinated dimethyl carbonate derivative, a fluorinated ethyl methyl carbonate derivative, and a fluorinated diethyl carbonate derivative.

Examples of the fluorinated dimethyl carbonate derivative include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoromethyl) carbonate, and the like.
Fluorinated ethyl methyl carbonate derivatives include (2-fluoroethyl) methyl carbonate, ethyl fluoromethyl carbonate, (2,2-difluoroethyl) methyl carbonate, (2-fluoroethyl) fluoromethyl carbonate, ethyl difluoromethyl carbonate, ( 2,2,2-trifluoroethyl) methyl carbonate, (2,
2-Difluoroethyl) fluoromethyl carbonate, (2-fluoroethyl) difluoromethyl carbonate, ethyl trifluoromethyl carbonate and the like.

  Fluorinated diethyl carbonate derivatives include ethyl- (2-fluoroethyl) carbonate, ethyl- (2,2-difluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, ethyl- (2,2,2-trifluoro). Ethyl) carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2,2-trifluoroethyl-2′-fluoroethyl carbonate, 2,2, Examples include 2-trifluoroethyl-2 ′, 2′-difluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate, and the like.

The fluorinated chain carbonate represented by the general formula (2) may be used alone or in combination of two or more in any combination and ratio.
The blending amount of the fluorinated chain carbonate represented by the general formula (2) is preferably 40% by volume or more, more preferably 45% by volume or more, and most preferably 50% by volume in 100% by volume of the non-aqueous solvent. That's it. By setting the lower limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, and not only the handling during injection becomes easy, but also the decrease in ionic conductivity is suppressed. It becomes easy to make the large current discharge characteristic of a secondary battery and the battery characteristic at the time of low temperature into a favorable range. The fluorinated chain carbonate represented by the general formula (2) is 90% by volume or less, more preferably 80% by volume or less, and most preferably 75% by volume or less in 100% by volume of the non-aqueous solvent. preferable. By setting the upper limit in this way, avoiding a decrease in electrical conductivity due to a decrease in the dielectric constant of the nonaqueous electrolyte, the large current discharge characteristics of the nonaqueous electrolyte secondary battery and the battery characteristics at low temperatures can be achieved. It becomes easy to make it a good range.
<Cyclic carbonate represented by the general formula (3)>

(In general formula (3), R ₄ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different from each other.)
Examples of the cyclic carbonate represented by the general formula (3) (hereinafter also referred to as cyclic carbonate) include those having an alkylene group having 2 to 4 carbon atoms.
Specifically, examples of the cyclic carbonate having an alkylene group having 2 to 4 carbon atoms include ethylene carbonate, propylene carbonate, butylene carbonate and the like. Among these, ethylene carbonate and propylene carbonate are particularly preferable from the viewpoint of improving battery characteristics resulting from improvement of the degree of lithium ion dissociation and improving battery durability.

The cyclic carbonate represented by the general formula (3) may be used alone or in combination of two or more in any combination and ratio.
The blending amount of the cyclic carbonate represented by the general formula (3) is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. However, the lower limit of the blending amount when one kind is used alone is not In 100% by volume of an aqueous solvent, preferably 5% by volume or more, more preferably 10% by volume or more, further preferably 15% by volume or more, and more preferably 20% by volume or more, and particularly preferably 30% by volume or more. . By setting this range, the decrease in electrical conductivity resulting from the decrease in the dielectric constant of the non-aqueous electrolyte is avoided, and the large current discharge characteristics, negative electrode stability, and cycle characteristics of the non-aqueous electrolyte secondary battery are good. It becomes easy to be in a range. The upper limit is preferably 70% by volume or less, more preferably 60% by volume or less, most preferably 50% by volume or less. By setting it as this range, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in ionic conductivity is suppressed, and as a result, the load characteristics and durability of the non-aqueous electrolyte secondary battery are easily set in a favorable range.

  The total blending amount of the fluorinated cyclic carbonate represented by the general formula (1) and the cyclic carbonate represented by the general formula (3) is preferably 100% by volume or more, more preferably 15% by volume or more. Preferably it is 20 volume% or more, Most preferably, it is 25 volume% or more, Preferably it is 80 volume% or less, More preferably, it is 70 volume% or less, More preferably, it is 60 volume% or less, Most preferably, it is 50 volume% or less. is there. If it is this range, a non-aqueous electrolyte secondary battery will be easy to express sufficient cycling characteristics improvement effect, and it will be easy to avoid the fall of a high temperature storage characteristic, and the fall of the discharge capacity maintenance factor by the increase in gas generation amount.

  Further, in 100% by volume of a cyclic carbonate solvent comprising the fluorinated cyclic carbonate represented by the general formula (1) and the cyclic carbonate represented by the general formula (3), the cyclic carbonate represented by the general formula (3) is blended. The amount is preferably 50% or more, more preferably 55% or more, and still more preferably 60% or more. Thus, by specifying the amount of the cyclic carbonate represented by the general formula (3), the gas generation amount is suppressed, and the effect of improving the cycle characteristics tends to be easily exhibited.

  Further, the total amount of the fluorinated chain carbonate represented by the general formula (2) and the cyclic carbonate represented by the general formula (3) is 100% by volume in the non-aqueous solvent, preferably 50% by volume or more, More preferably, it is 60 volume% or more, Most preferably, it is 70 volume% or more, Preferably it is 97 volume% or less, More preferably, it is 95 volume% or less. If it is this range, a non-aqueous electrolyte secondary battery will be easy to express sufficient cycling characteristics improvement effect, and it will be easy to avoid the fall of a high temperature storage characteristic, and the fall of the discharge capacity maintenance factor by the increase in gas generation amount.

  In addition, in 100% by volume of a carbonate solvent composed of the fluorinated chain carbonate represented by the general formula (2) and the cyclic carbonate represented by the general formula (3), the cyclic carbonate represented by the general formula (3) is blended. The amount is preferably 50% or less, more preferably 45% or less, and still more preferably 40% or less. Thus, by specifying the amount of the cyclic carbonate represented by the general formula (3), the gas generation amount is suppressed, and the effect of improving the cycle characteristics tends to be easily exhibited.

  Further, the non-aqueous electrolyte contains a fluorinated cyclic carbonate represented by the general formula (1) and a fluorinated chain carbonate represented by the general formula (2), or is represented by the general formula (1). When the fluorinated cyclic carbonate, the fluorinated chain carbonate represented by the general formula (2), and the cyclic carbonate represented by the general formula (3) are contained, the total amount of these carbonates is non-aqueous. In 100 volume% of solvent, Preferably it is 50 volume% or more, More preferably, it is 70 volume% or more, More preferably, it is 75 volume% or more, Most preferably, it is 85 volume% or more. Within this range, not only the durability of the battery is excellent, but also the viscosity of the non-aqueous electrolyte is set to an appropriate range, the decrease in ionic conductivity is suppressed, and consequently the large current discharge characteristics of the non-aqueous electrolyte secondary battery It becomes easy to make the battery characteristics at a low temperature and a good range. The upper limit is not particularly set and may be 100% by volume.

  In addition, the cyclic carbonate which has a fluorine atom represented by General formula (1) expresses an effective function not only as a solvent but also as an auxiliary agent described in 1-3 below. There is no clear boundary in the blending amount when used as a cyclic carbonate solvent / auxiliary having a fluorine atom, and the blending amount described in the previous paragraph can be followed as it is.

1-1-2. Other solvents In addition to the fluorinated cyclic carbonate represented by the general formula (1), the fluorinated chain carbonate represented by the general formula (2), and the cyclic carbonate represented by the general formula (3), Various solvents may be mixed and used as long as the effect is not impaired. Examples of these solvents include non-fluorinated chain carbonates, cyclic carboxylic acid esters, chain carboxylic acid esters, ether compounds, and sulfone compounds.

<Non-fluorinated chain carbonate>
As a non-fluorinated chain carbonate, a C3-C7 thing is preferable. Specifically, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-i-propyl carbonate, n-propyl-i-propyl carbonate, ethyl methyl carbonate, methyl n-propyl carbonate, n-butyl methyl carbonate I-butyl methyl carbonate, t-butyl methyl carbonate, ethyl-n-propyl carbonate, n-butyl ethyl carbonate, i-butyl ethyl carbonate, t-butyl ethyl carbonate and the like.

Among them, dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, di-i-propyl carbonate, n-propyl-i-propyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate are preferable, and dimethyl carbonate is particularly preferable. Diethyl carbonate and ethyl methyl carbonate.
The blending amount of the non-fluorinated chain carbonate is usually in 100% by volume of the non-aqueous solvent, preferably 0.1% by volume or more, more preferably 0.3% by volume or more, and further preferably 0.5% by volume or more. is there. By setting the lower limit in this manner, the electrical conductivity of the non-aqueous electrolyte solution is improved, and the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily improved. Moreover, the compounding quantity of a non-fluorinated chain carbonate becomes like this. Preferably it is 50 volume% or less, More preferably, it is 30 volume% or less, More preferably, it is 20 volume% or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. It becomes easy to make a characteristic into a favorable range.

<Cyclic carboxylic acid ester>
Examples of the cyclic carboxylic acid ester include those having 3 to 12 carbon atoms in the structural formula.
Specific examples include gamma butyrolactone, gamma valerolactone, gamma caprolactone, epsilon caprolactone, and the like. Among these, gamma butyrolactone is particularly preferable from the viewpoint of improving battery characteristics resulting from an improvement in the degree of lithium ion dissociation.

  The compounding amount of the cyclic carboxylic acid ester is usually 0.3% by volume or more, more preferably 0.5% by volume or more, and further preferably 1% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this manner, the electrical conductivity of the non-aqueous electrolyte solution is improved, and the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily improved. Moreover, the compounding quantity of cyclic carboxylic acid ester becomes like this. Preferably it is 15 volume% or less, More preferably, it is 10 volume% or less, More preferably, it is 5 volume% or less. By setting the upper limit in this way, the viscosity of the non-aqueous electrolyte solution is set to an appropriate range, a decrease in electrical conductivity is avoided, an increase in negative electrode resistance is suppressed, and a large current discharge of the non-aqueous electrolyte secondary battery is performed. It becomes easy to make a characteristic into a favorable range.

<Chain carboxylic acid ester>
Examples of the chain carboxylic acid ester include those having 3 to 7 carbon atoms in the structural formula.
Specifically, methyl acetate, ethyl acetate, acetic acid-n-propyl, isopropyl acetate, acetic acid-n-butyl, isobutyl acetate, acetic acid-t-butyl, methyl propionate, ethyl propionate, propionate-n-propyl, Isopropyl propionate, n-butyl propionate, isobutyl propionate, t-butyl propionate, methyl butyrate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, methyl isobutyrate, ethyl isobutyrate, isobutyric acid-n- Examples include propyl and isopropyl isobutyrate.
Among them, methyl acetate, ethyl acetate, acetate-n-propyl, acetate-n-butyl, methyl propionate, ethyl propionate, propionate-n-propyl, isopropyl propionate, methyl butyrate, ethyl butyrate, etc. It is preferable from the viewpoint of improvement of ionic conductivity.

  The amount of the chain carboxylic acid ester is usually 0.3% by volume or more, more preferably 0.5% by volume or more, and further preferably 1% by volume or more in 100% by volume of the non-aqueous solvent. By setting the lower limit in this way, the electrical conductivity of the non-aqueous electrolyte solution is improved, and the large current discharge characteristics of the non-aqueous electrolyte secondary battery are easily improved. Further, the amount of the chain carboxylic acid ester is preferably 15% by volume or less, more preferably 10% by volume or less, and further preferably 5% by volume or less in 100% by volume of the non-aqueous solvent. By setting the upper limit in this manner, an increase in negative electrode resistance is suppressed, and the large current discharge characteristics and cycle characteristics of the non-aqueous electrolyte secondary battery are easily set in a favorable range.

<Ether compound>
As the ether compound, a chain ether having 3 to 10 carbon atoms in which part of hydrogen may be substituted with fluorine, and a cyclic ether having 3 to 6 carbon atoms are preferable.
Examples of the chain ether having 3 to 10 carbon atoms include diethyl ether, bis (2-fluoroethyl) ether, bis (2,2-difluoroethyl) ether, bis (2,2,2-trifluoroethyl) ether, ethyl (2-fluoroethyl) ether, ethyl (2,2,2-trifluoroethyl) ether, ethyl (1,1,2,2-tetrafluoroethyl) ether, (2-fluoroethyl) (2,2,2 -Trifluoroethyl) ether, (2-fluoroethyl) (1,1,2,2-tetrafluoroethyl) ether, (1,1,2,2-tetrafluoroethyl) (2,2,2-trifluoro Ethyl) ether, ethyl-n-propyl ether, ethyl (3-fluoro-n-propyl) ether, ethyl (3,3,3-trifluoro-n-pro ) Ether, ethyl (2,2,3,3-tetrafluoro-n-propyl) ether, ethyl (2,2,3,3,3-pentafluoro-n-propyl) ether, 2-fluoroethyl-n -Propyl ether, (2-fluoroethyl) (3-fluoro-n-propyl) ether, (2-fluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (2-fluoroethyl) ( 2,2,3,3-tetrafluoro-n-propyl) ether, (2-fluoroethyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, 2,2,2-tri Fluoroethyl-n-propyl ether, (3-fluoro-n-propyl) (2,2,2-trifluoroethyl) ether, (2,2,2-trifluoroethyl) (3,3,3- (Rifluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n-propyl) (2,2,2-trifluoroethyl) ether, (2,2,3,3,3-penta Fluoro-n-propyl) (2,2,2-trifluoroethyl) ether, n-propyl (1,1,2,2-tetrafluoroethyl) ether, (3-fluoro-n-propyl) (1,1 , 2,2-tetrafluoroethyl) ether, (1,1,2,2-tetrafluoroethyl) (3,3,3-trifluoro-n-propyl) ether, (1,1,2,2-tetra) Fluoroethyl) (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3,3-pentafluoro-n-propyl) (1,1,2,2-tetrafluoro) Ethyl) ether, di-n- Propyl ether, (3-fluoro-n-propyl) (n-propyl) ether, (n-propyl) (3,3,3-trifluoro-n-propyl) ether, (n-propyl) (2,2, 3,3-tetrafluoro-n-propyl) ether, (2,2,3,3,3-pentafluoro-n-propyl) (n-propyl) ether, bis (3-fluoro-n-
Propyl) ether, (3-fluoro-n-propyl) (3,3,3-trifluoro-n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3-tetrafluoro- n-propyl) ether, (3-fluoro-n-propyl) (2,2,3,3,3-pentafluoro-n-propyl) ether, bis (3,3,3-trifluoro-n-propyl) ether Ether, (2,2,3,3-tetrafluoro-n-propyl) (3,3,3-trifluoro-n-propyl) ether, (2,2,3,3,3-pentafluoro-n- Propyl) (3,3,3-trifluoro-n-propyl) ether, bis (2,2,3,3-tetrafluoro-n-propyl) ether, (2,2,3,3-tetrafluoro-n -Propyl) (2,2,3, , 3-pentafluoro-n-propyl) ether, bis (2,2,3,3,3-pentafluoro-n-propyl) ether, di-n-butyl ether, dimethoxymethane, ethoxymethoxymethane, (2-fluoro Ethoxy) methoxymethane, methoxy (2,2,2-trifluoroethoxy) methane, methoxy (1,1,2,2-tetrafluoroethoxy) methane, diethoxymethane, ethoxy (2-fluoroethoxy) methane, ethoxy ( 2,2,2-trifluoroethoxy) methane, ethoxy (1,1,2,2-tetrafluoroethoxy) methane, bis (2-fluoroethoxy) methane, (2-fluoroethoxy) (2,2,2- Trifluoroethoxy) methane, (2-fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) Methane, bis (2,2,2-trifluoroethoxy) methane, (1,1,2,2-tetrafluoroethoxy) (2,2,2-trifluoroethoxy) methane, bis (1,1,2, 2-tetrafluoroethoxy) methane, dimethoxyethane, ethoxymethoxyethane, (2-fluoroethoxy) methoxyethane, methoxy (2,2,2-trifluoroethoxy) ethane, methoxy (1,1,2,2-tetrafluoro) Ethoxy) ethane, diethoxyethane, ethoxy (2-fluoroethoxy) ethane, ethoxy (2,2,2-trifluoroethoxy) ethane, ethoxy (1,1,2,2-tetrafluoroethoxy) ethane, bis (2 -Fluoroethoxy) ethane, (2-fluoroethoxy) (2,2,2-trifluoroethoxy) ethane, (2- Fluoroethoxy) (1,1,2,2-tetrafluoroethoxy) ethane, bis (2,2,2-trifluoroethoxy) ethane, (1,1,2,2-tetrafluoroethoxy) (2,2, 2-trifluoroethoxy) ethane, bis (1,1,2,2-tetrafluoroethoxy) ethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether and the like.

Examples of the cyclic ether having 3 to 6 carbon atoms include tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, 1,3-dioxane, 2-methyl-1,3-dioxane, 4-methyl-1,3-dioxane, 1 , 4-dioxane and the like, and fluorinated compounds thereof.
Among them, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, and diethylene glycol dimethyl ether have high solvating ability to lithium ions and improve ion dissociation. Of these, dimethoxymethane, diethoxymethane, and ethoxymethoxymethane are preferable because they have low viscosity and give high ionic conductivity.

  The compounding amount of the ether compound is usually 0.3% by volume or more, more preferably 0.5% by volume or more, still more preferably 1% by volume or more in 100% by volume of the non-aqueous solvent, and preferably 40%. Volume% or less, More preferably, it is 35 volume% or less, More preferably, it is 30 volume% or less. If it is this range, it is easy to ensure the improvement effect of the lithium ion dissociation degree of chain ether, and the improvement of the ionic conductivity derived from a viscosity fall, and when a negative electrode active material is a carbonaceous material, a chain ether with lithium ion It is easy to avoid a situation where the capacity is reduced due to co-insertion.

<Sulfone compound>
As the sulfone compound, a cyclic sulfone having 3 to 6 carbon atoms and a chain sulfone having 2 to 6 carbon atoms are preferable. The number of sulfonyl groups in one molecule is preferably 1 or 2.
Examples of the cyclic sulfone include trimethylene sulfones, tetramethylene sulfones, and hexamethylene sulfones that are monosulfone compounds; trimethylene disulfones, tetramethylene disulfones, and hexamethylene disulfones that are disulfone compounds. Among these, from the viewpoint of dielectric constant and viscosity, tetramethylene sulfones, tetramethylene disulfones, hexamethylene sulfones, and hexamethylene disulfones are more preferable, and tetramethylene sulfones (sulfolanes) are particularly preferable.

  The sulfolane is preferably sulfolane and / or a sulfolane derivative (hereinafter sometimes abbreviated as “sulfolane” including sulfolane). As the sulfolane derivative, one in which one or more hydrogen atoms bonded to the carbon atom constituting the sulfolane ring are substituted with a fluorine atom or an alkyl group is preferable. Among them, 2-methylsulfolane, 3-methylsulfolane, 2-fluorosulfolane, 3-fluorosulfolane, 2,2-difluorosulfolane, 2,3-difluorosulfolane, 2,4-difluorosulfolane, 2,5-difluorosulfolane, 3,4-difluorosulfolane, 2-fluoro-3-methylsulfolane, 2-fluoro-2-methylsulfolane, 3-fluoro-3-methylsulfolane, 3-fluoro-2-methylsulfolane, 4-fluoro-3-methyl Sulfolane, 4-fluoro-2-methylsulfolane, 5-fluoro-3-methylsulfolane, 5-fluoro-2-methylsulfolane, 2-fluoromethylsulfolane, 3-fluoromethylsulfolane, 2-difluoromethylsulfolane, 3-difluoro Methyl sulfolane, 2- Trifluoromethylsulfolane, 3-trifluoromethylsulfolane, 2-fluoro-3- (trifluoromethyl) sulfolane, 3-fluoro-3- (trifluoromethyl) sulfolane, 4-fluoro-3- (trifluoromethyl) sulfolane , 5-fluoro-3- (trifluoromethyl) sulfolane and the like are preferable in terms of high ionic conductivity and high input / output.

  As the chain sulfone, dimethylsulfone, ethylmethylsulfone, diethylsulfone, methyl-n-propylsulfone, ethyl-n-propylsulfone, di-n-propylsulfone, i-propylmethylsulfone, isopropylethylsulfone, diisopropyl Sulfone, n-butylmethylsulfone, n-butylethylsulfone, t-butylmethylsulfone, t-butylethylsulfone, fluoromethylmethylsulfone, difluoromethylmethylsulfone, trifluoromethylmethylsulfone, (2-fluoro) ethylmethylsulfone , (2,2-difluoroethyl) methylsulfone, trifluoroethylmethylsulfone, pentafluoroethylmethylsulfone, ethylfluoromethylsulfone, ethyldifluoromethylsulfone, Tilt trifluoromethyl sulfone, perfluoroethyl methyl sulfone, ethyl (2,2,2-trifluoroethyl) sulfone, ethyl pentafluoroethyl sulfone, bis (trifluoroethyl) sulfone, bis (perfluoroethyl) sulfone, fluoromethyl N-propylsulfone, difluoromethyl-n-propylsulfone, trifluoromethyl-n-propylsulfone, fluoromethyl-i-propylsulfone, difluoromethyl-i-propylsulfone, trifluoromethyl-i-propylsulfone, trifluoro Ethyl-n-propylsulfone, trifluoroethyl-i-propylsulfone, pentafluoroethyl-n-propylsulfone, pentafluoroethyl-i-propylsulfone, n-butyl (2,2,2-trimethyl) Ruoroechiru) Rusuruhon, t- butyl (2,2,2-trifluoroethyl) sulfone, n- butyl pentafluoroethyl sulfone, t- butyl pentafluoroethyl sulfone, and the like.

Among them, dimethylsulfone, ethylmethylsulfone, diethylsulfone, methyl-n-propylsulfone, methyl-i-propylsulfone, methyl-n-butylsulfone, t-butylmethylsulfone, fluoromethylmethylsulfone, difluoromethylmethylsulfone, tri Fluoromethyl methyl sulfone, (2-fluoroethyl) methyl sulfone, (2
, 2-difluoroethyl) methylsulfone, methyltrifluoroethylsulfone, methylpentafluoroethylsulfone, ethylfluoromethylsulfone, difluoromethylethylsulfone, ethyltrifluoromethylsulfone, ethyltrifluoroethylsulfone, ethylpentafluoroethylsulfone, n -Ion conduction of propyl trifluoromethyl sulfone, i-propyl trifluoromethyl sulfone, n-butyl trifluoroethyl sulfone, t-butyl trifluoroethyl sulfone, n-butyl trifluoromethyl sulfone, t-butyl trifluoromethyl sulfone, etc. It is preferable because of its high degree of input and output.

  The compounding amount of the sulfone compound is usually 0.3% by volume or more, more preferably 0.5% by volume or more, and further preferably 1% by volume or more in 100% by volume of the nonaqueous solvent. Is 40% by volume or less, more preferably 35% by volume or less, and still more preferably 30% by volume or less. Within this range, durability improvement effects such as cycle characteristics and storage characteristics can be easily obtained, and the viscosity of the non-aqueous electrolyte can be set to an appropriate range to avoid a decrease in electrical conductivity. When charging / discharging an aqueous electrolyte secondary battery at a high current density, it is easy to avoid a situation in which the charge / discharge capacity retention rate decreases.

1-2. Electrolyte <Lithium salt>
As the electrolyte, a lithium salt is usually used. The lithium salt is not particularly limited as long as it is known to be used for this purpose, and any lithium salt can be used. Specific examples include the following.

For example, inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAlF ₄ , LiSbF ₆ , LiNbF ₆ , LiTaF ₆ , LiWF ₇ ;
Lithium fluorophosphates such as LiPO ₃ F and LiPO ₂ F ₂ ;
Lithium tungstates such as LiWOF ₅ ;
HCO ₂ Li, CH ₃ CO ₂ Li, CH ₂ FCO ₂ Li, CHF ₂ CO ₂ Li,
Carboxylic acid lithium salts such as CF ₃ CO ₂ Li, CF ₃ CH ₂ CO ₂ Li, CF ₃ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ CO ₂ Li, CF ₃ CF ₂ CF ₂ CF ₂ CO ₂ Li;
FSO ₃ Li, CH ₃ SO ₃ Li, CH ₂ FSO ₃ Li, CHF ₂ SO ₃ Li,
CF ₃ SO ₃ Li, CF ₃ CF ₂ SO ₃ Li, CF ₃ CF ₂ CF ₂ SO ₃ Li,
Sulfonic acid lithium salts such as CF ₃ CF ₂ CF ₂ CF ₂ SO ₃ Li;

LiN (FCO) ₂ , LiN (FCO) (FSO ₂ ), LiN (FSO ₂ ) ₂ , L
iN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F
₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiN (CF ₃ SO ₂ )
Lithium imide salts such as (C ₄ F ₉ SO ₂ ); LiC (FSO ₂ ) ₃ , LiC (CF
₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) _{3 and} other lithium methide salts;
Lithium oxalatoborate salts such as lithium difluorooxalatoborate and lithium bis (oxalato) borate;
Lithium oxalate phosphate salts such as lithium tetrafluorooxalatophosphate, lithium difluorobis (oxalato) phosphate, lithium tris (oxalato) phosphate;

In addition, LiPF ₄ (CF ₃ ) ₂ , LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiBF ₃ C ₃ F ₇ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (
C ₂ F ₅ ) ₂ , LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ )
Fluorine-containing organic lithium salts such as ₂ ;
Etc.

Among them, LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiTaF ₆ , LiPO ₂ F ₂ , FSO ₃ Li, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ )
(CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropanedi Sulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO ₂ ) ₃ , lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium tetrafluorooxalatophosphate, lithium Difluorobisoxalatophosphate, lithium tris (oxalato) phosphate, LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃ , Li
PF ₃ (C ₂ F ₅ ) ₃ or the like is particularly preferable because it has an effect of improving output characteristics, high-rate charge / discharge characteristics, high-temperature storage characteristics, cycle characteristics, and the like.

These lithium salts may be used alone or in combination of two or more. Preferred examples when two or more are used in combination include LiPF ₆ and LiBF ₄ , LiPF ₆ and FSO ₃ Li,
LiPF ₆ and LiPO ₂ F ₂ are used in combination, and have the effect of improving load characteristics and cycle characteristics. Among these, LiPF ₆ and FSO ₃ Li, LiPF ₆ and LiPO ₂ F
The combination of ₂ is preferable because the effect is remarkable.

When LiPF ₆ and LiBF ₄ , LiPF ₆ and FSO ₃ Li are used in combination, the concentration of LiBF ₄ or FSO ₃ Li with respect to 100% by mass of the total amount of the non-aqueous electrolyte is not limited, and the effect of the present invention is not significantly impaired. As long as it is optional, it is usually 0.01% by mass or more, preferably 0.1% by mass or more, and the upper limit is usually 30% by mass or less, preferably 20% with respect to the non-aqueous electrolyte solution of the present invention. It is below mass%. On the other hand, LiPF ₆ and LiPO ₂ F
Concentration of LiPO ₂ F ₂ also to non-aqueous electrolyte entire 100 wt% in the case of the _second combination is not limited to the amount, but not limited unless significantly impairing the effects of the present invention, the nonaqueous electrolyte of the present invention It is usually 0.001% by mass or more, preferably 0.01% by mass or more, based on the liquid, while its upper limit is usually 10% by mass or less, preferably 5% by mass or less. Within this range, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature characteristics are improved. On the other hand, if it is too much, it may be deposited at low temperature to deteriorate the battery characteristics, and if it is too little, the effect of improving the low temperature characteristics, cycle characteristics, high temperature storage characteristics, etc. may be reduced.

Here, the preparation of the electrolyte solution in the case of incorporating the LiPO ₂ F ₂ in the electrolyte solution, Ya separately active material method and later be added to the electrolytic solution containing LiPF ₆ and LiPO ₂ F ₂ synthesized by a known method A method of generating LiPO ₂ F ₂ in the system when water is allowed to coexist in a battery component such as an electrode plate and assembling a battery using an electrolyte containing LiPF ₆ is used. You may use the method of.

The method for measuring the content of LiPO ₂ F ₂ in the non-aqueous electrolyte and the non-aqueous electrolyte battery is not particularly limited, and any known method can be used. Examples include ion chromatography and F nuclear magnetic resonance spectroscopy (hereinafter sometimes abbreviated as NMR).
Another example is the combined use of an inorganic lithium salt and an organic lithium salt, and the combined use of both has the effect of suppressing deterioration due to high-temperature storage. As the organic lithium salt, CF ₃ SO ₃ Li, LiN (FSO ₂ ) ₂ , LiN (FSO ₂ ) (CF ₃ SO ₂ ), LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , Lithium cyclic 1,2-perfluoroethanedisulfonylimide, lithium cyclic 1,3-perfluoropropane disulfonylimide, LiC (FSO ₂ ) ₃ , LiC (CF ₃ SO ₂ ) ₃ , LiC (C ₂ F ₅ SO
₂ ) ₃ , Lithium bisoxalatoborate, Lithium difluorooxalatoborate, Lithium tetrafluorooxalatophosphate, Lithium difluorobisoxalatophosphate, LiBF ₃ CF ₃ , LiBF ₃ C ₂ F ₅ , LiPF ₃ (CF ₃ ) ₃
LiPF ₃ (C ₂ F ₅ ) ₃ or the like is preferable. In this case, the ratio of the organic lithium salt to 100% by mass of the whole non-aqueous electrolyte is preferably 0.1% by mass or more, particularly preferably 0.5% by mass or more, preferably 30% by mass or less, particularly preferably. It is 20 mass% or less.

  The concentration of these lithium salts in the non-aqueous electrolyte solution is not particularly limited as long as the effects of the present invention are not impaired. Therefore, the total molar concentration of lithium in the non-aqueous electrolyte is preferably 0.3 mol / L or more, more preferably 0.4 mol / L or more, and further preferably 0.5 mol / L or more. Preferably it is 3 mol / L or less, More preferably, it is 2.5 mol / L or less, More preferably, it is 2.0 mol / L or less. If it is this range, effects, such as a low temperature characteristic, cycling characteristics, and a high temperature characteristic, will improve. On the other hand, if the total molar concentration of lithium is too low, the electrical conductivity of the electrolyte may be insufficient. On the other hand, if the concentration is too high, the electrical conductivity may decrease due to an increase in viscosity. May decrease.

1-3. Auxiliary In the non-aqueous electrolyte battery of the present invention, an auxiliary may be appropriately used according to the purpose. As the auxiliary agent, the following compounds having a carbon-carbon triple bond, a cyclic carbonate having an unsaturated bond excluding the carbon-carbon triple bond, an unsaturated cyclic carbonate having a fluorine atom, a cyclic sulfonate ester, a cyano group , Diisocyanate compounds, other auxiliaries, and the like.

<Compound having carbon-carbon triple bond>
In the non-aqueous electrolyte of the present invention, a compound having a carbon-carbon triple bond can be contained in order to form a film on the surface of the negative electrode of the non-aqueous electrolyte battery and to extend the life of the battery. The compound having a carbon-carbon triple bond is not particularly limited as long as it is a compound having a carbon-carbon triple bond, but a chain compound having a carbon-carbon triple bond and a ring having a carbon-carbon triple bond. Classified as a compound.
As the chain compound having a carbon-carbon triple bond, one or more alkyne derivatives represented by the following general formula (4) or formula (5) are preferably used.

In general formulas (4) to (5), R _{5 to} R ₁₃ are each independently a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, or a carbon atom having 6 to 12 carbon atoms. An aryl group, R ₆ and R ₇ , R ₉ and R ₁₀ , R ₁₁ and R ₁₂ may be bonded to each other to form a cycloalkyl group having 3 to 6 carbon atoms; x and y represent an integer of 1 or 2. Y ₁ and Y
₂ is represented by Formula (6), and may be the same or different.

Z ₁ represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, or an aralkyl group having 7 to 12 carbon atoms.
Among the compounds represented by the general formula (4), 2-propynylmethyl carbonate, 1-methyl-2-propynylmethyl carbonate, 1,1-dimethyl-2-propynylmethyl carbonate, 2-propynylethyl carbonate, 1-methyl 2-propynyl ethyl carbonate, 1,1-dimethyl-2-propynyl ethyl carbonate, 2-butynyl methyl carbonate, 1-methyl-2-butynyl methyl carbonate, 1,1-dimethyl-2-butynyl methyl carbonate -2-propynyl formate, 1-methyl-2-propynyl formate, 1,1-dimethyl-2-propynyl formate, 2-butynyl formate, 1-methyl-2-butynyl formate, formic acid-1,1 -Dimethyl-2-butynyl acetate-2-propynyl acetate, 1-methyl-2-propynyl acetate 1,1-dimethyl-2-propynyl acetate, 2-butynyl acetate, 1-methyl-2-butynyl acetate, 1,1-dimethyl-2-butynyl acetate, 2-propynylmethyl oxalate, 1-methyl 2-propynylmethyl oxalate, 1,1-dimethyl-2-propynylmethyl oxalate, 2-butynylmethyl oxalate, 1-methyl-2-butynylmethyl oxalate, 1,1-dimethyl-2-buty Nylmethyl oxalate, 2-propynyl ethyl oxalate, 1-methyl-2-propynyl ethyl oxalate, 1,1-dimethyl-2-propynyl ethyl oxalate, 2-butynyl ethyl oxalate, 1-methyl-2- Butynylethyl oxalate, 1,1-dimethyl-2-butynylethyl oxalate, methanesulfonic acid -Propynyl, methanesulfonic acid-1-methyl-2-propynyl, methanesulfonic acid-1,1-dimethyl-2-propynyl, methanesulfonic acid-2-butynyl, methanesulfonic acid-1-methyl-2-butynyl, methane Sulfonic acid-1,1-dimethyl-2-butynyl, trifluoromethanesulfonic acid-2-propynyl, trifluoromethanesulfonic acid-1-methyl-2-propynyl, trifluoromethanesulfonic acid-1,1-dimethyl-2-propynyl, Trifluoromethanesulfonic acid-2-butynyl, trifluoromethanesulfonic acid-1-methyl-2-butynyl, trifluoromethanesulfonic acid-1,1-dimethyl-2-butynyl, trifluoroethanesulfonic acid-2-propynyl, trifluoroethane Sulfonic acid-1-methyl-2-propi Nyl, trifluoroethanesulfonic acid-1,1-dimethyl-2-propynyl, trifluoroethanesulfonic acid-2-butynyl, trifluoroethanesulfonic acid-1-methyl-2-butynyl, trifluoroethanesulfonic acid-1, 1-dimethyl-2-butynyl, benzenesulfonic acid-2-propynyl, benzenesulfonic acid-1-methyl-2-propynyl, benzenesulfonic acid-1,1-dimethyl-2-propynyl, benzenesulfonic acid-2-butynyl, Benzenesulfonic acid-1-methyl-2-butynyl, benzenesulfonic acid-1,1-dimethyl-2-butynyl, p-toluenesulfonic acid-2-propynyl, p-toluenesulfonic acid-1-methyl-2-propynyl, p-Toluenesulfonic acid-1,1-dimethyl-2-propynyl, p-toluene 2-butynyl phonate, p-toluenesulfonic acid-1-methyl-2-butynyl, p-toluenesulfonic acid-1,1-dimethyl-2-butynyl, methylsulfuric acid-2-propynyl, methylsulfuric acid-1-methyl 2-propynyl, methyl sulfate-1,1-dimethyl-2-propynyl, methyl sulfate-2-butynyl, methyl sulfate-1-methyl-2-butynyl, methyl sulfate-1,1-dimethyl-2-propynyl, ethyl 2-propynyl sulfate, ethyl sulfate-1-methyl-2-propynyl, ethyl sulfate-1,1-dimethyl-2-propynyl, ethyl sulfate-2-butynyl, ethyl sulfate-1-methyl-2-butynyl, ethyl sulfate One or more selected from -1,1-dimethyl-2-butynyl is preferred,

  2-propynylmethyl carbonate, 1-methyl-2-propynylmethyl carbonate, 1,1-dimethyl-2-propynylmethyl carbonate, 2-propynylethyl carbonate, 2-butynylmethyl carbonate, formic acid-2-propynyl, formic acid-1 -Methyl-2-propynyl, formic acid-1,1-dimethyl-2-propynyl, formic acid-2-butynyl, acetic acid-2-propynyl, acetic acid-1-methyl-2-propynyl, acetic acid-1,1-dimethyl-2 -Propynyl, 2-butynyl acetate, 2-propynyl methyl oxalate, 1-methyl-2-propynyl methyl oxalate, 1,1-dimethyl-2-propynyl methyl oxalate, 2-butynyl methyl oxalate, methanesulfone 2-propynyl acid, methanesulfonic acid-1-methyl-2-pro Nyl, methanesulfonic acid-1,1-dimethyl-2-propynyl, methanesulfonic acid-2-butynyl, methanesulfonic acid-1-methyl-2-butynyl, methylsulfuric acid-2-propynyl, methylsulfuric acid-1-methyl- It is preferable to contain one or more selected from 2-propynyl, methylsulfate-1,1-dimethyl-2-propynyl, and methylsulfate-2-butynyl.

Among the compounds represented by the general formula (5), di (2-propynyl) carbonate, di (2-butynyl) carbonate, di (1-methyl-2-propynyl) carbonate, di (1-methyl-2-butynyl) ) Carbonate, di (1,1-dimethyl-2-propynyl) carbonate, di (1,1-dimethyl-2-butynyl) carbonate, di (2-propynyl) oxalate, di (2-butynyl) oxalate, di (1 -Methyl-2-propynyl) oxalate, di (1-methyl-2-butynyl) oxalate, di (1,1-dimethyl-2-propynyl) oxalate, di (1,1-dimethyl-2-butynyl) oxalate, di (2-propynyl) sulfite, di (2-butynyl) sulfite, di (1-methyl-2-propynyl) sulfite, (1-methyl-2-butynyl) sulfite, di (1,1-dimethyl-2-propynyl) sulfite, di (1,1-dimethyl-2-butynyl) sulfite, di (2-propynyl) sulfuric acid, Di (2-butynyl) sulfuric acid, di (1-methyl-2-propynyl) sulfuric acid, di (1-methyl-2-butynyl) sulfuric acid, di (1,1-dimethyl-2-propynyl) sulfuric acid, di (1, 1 or more types selected from 1-dimethyl-2-butynyl) sulfuric acid are preferable, and in particular, di (2-propynyl) carbonate, di (2-butynyl) carbonate, di (2-propynyl) oxalate, di (2-butynyl) Oxalate, di (2-propynyl) sulfuric acid,
It is preferable to contain one or more selected from di (2-butynyl) sulfuric acid.

  Among the alkyne derivatives, the most preferred compounds are 2-propynylmethyl carbonate, 2-propynylethyl carbonate, 2-butynylmethyl carbonate, formate-2-propynyl, formate-2-butynyl, acetate-2-propynyl, acetate- 2-butynyl, 2-propynylmethyl oxalate, 2-butynylmethyl oxalate, methanesulfonic acid-2-propynyl, methanesulfonic acid-2-butynyl, methanesulfonic acid-1-methyl-2-butynyl, methylsulfuric acid 2-propynyl, methyl sulfate-2-butynyl, di (2-propynyl) carbonate, di (2-butynyl) carbonate, di (2-propynyl) oxalate, di (2-butynyl) oxalate, di (2-propynyl) sulfuric acid And at least selected from di (2-butynyl) sulfuric acid Is one or more compounds.

The compounds represented by the general formulas (4) to (5) may be used alone or in combination of two or more in any combination and ratio. Moreover, the compounding quantity of the compound represented by General formula (4)-(5) is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary. The compounding amount of the compounds represented by the general formulas (4) to (5) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably in 100% by mass of the non-aqueous electrolyte solution. It is 0.1 mass% or more, Preferably it is 5 mass% or less, More preferably, it is 4 mass% or less, More preferably, it is 3 mass% or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid. On the other hand, if the amount is too small, the effects of the present invention may not be sufficiently exerted. If the amount is too large, the resistance may increase and the output and load characteristics may decrease.
Moreover, when the compound which has a carbon-carbon triple bond is a cyclic compound, it is preferable that it is a compound represented by following General formula (7).

(In the general formula (7), X and Z are CR ¹ ₂ , C═O, C═N—R ¹ , C═P—R ¹ , O, S.
, N—R ¹ and P—R ¹ may be the same or different. Y represents CR ¹ ₂ , C═O, S═O, S (═O) ₂ , P (═O) —R ² , P (═O) —OR ³ . In the formula, R and R ¹ are hydrogen, halogen, or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and may be the same or different. R ² is a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. R ³ is Li, NR ⁴ ₄ or a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent. R ⁴ is a hydrocarbon group having 1 to 20 carbon atoms which may have a substituent, and may be the same as or different from each other. n and m represent an integer of 0 or more. W has the same meaning as R, and may be the same as or different from R. )
In the general formula (7), X and Z is not particularly limited as long as the scope described in the aforementioned general formula (4), _{^{preferably, CR 1 2, O, S}} , N-R 1 is more preferred. Y is not particularly limited as long as it is within the range described in the general formula (14), but preferably C═O, S═O, S (═O) ₂ , P (═O) —R ² , P ( = O) -OR ³ is more preferred. R and R ¹ are represented by the general formula (
14) is not particularly limited as long as it is within the range described above, but preferably hydrogen, fluorine, a saturated aliphatic hydrocarbon group which may have a substituent, and an unsaturated aliphatic hydrocarbon which may have a substituent And an aromatic hydrocarbon group which may have a group or a substituent.

R ² and R ⁴ are not particularly limited as long as they are within the range described in the general formula (7), but are preferably a saturated aliphatic hydrocarbon group that may have a substituent or a substituent. Examples thereof include unsaturated aliphatic hydrocarbons and optionally substituted aromatic hydrocarbons / aromatic heterocycles.
R ³ is not particularly limited as long as it is in the range described in the general formula (7), but preferably Li, a saturated aliphatic hydrocarbon which may have a substituent, or an unsaturated which may have a substituent Examples thereof include an aliphatic hydrocarbon and an aromatic hydrocarbon / aromatic heterocycle which may have a substituent.

Substituents of saturated aliphatic hydrocarbons which may have substituents, unsaturated aliphatic hydrocarbons which may have substituents, aromatic hydrocarbons and aromatic heterocycles which may have substituents Is not particularly limited, but preferably has a saturated aliphatic hydrocarbon group, which may have a substituent such as halogen, carboxylic acid, carbonic acid, sulfonic acid, phosphoric acid, phosphorous acid, etc. And an unsaturated aliphatic hydrocarbon group that may be substituted, an ester of an aromatic hydrocarbon group that may have a substituent, and the like, more preferably halogen, and most preferably fluorine.

  Preferable saturated aliphatic hydrocarbons include, specifically, methyl group, ethyl group, fluoromethyl group, difluoromethyl group, trifluoromethyl group, 1-fluoroethyl group, 2-fluoroethyl group, 1,1-difluoroethyl. Group, 1,2-difluoroethyl group, 2,2-difluoroethyl group, 1,1,2-trifluoroethyl group, 1,2,2-trifluoroethyl group, 2,2,2-trifluoroethyl group A phenyl group, a cyclopentyl group, and a cyclohexyl group are preferred.

Specific preferred unsaturated aliphatic hydrocarbons include ethenyl, 1-fluoroethenyl, 2-fluoroethenyl, 1-methylethenyl, 2-propenyl, and 2-fluoro-2-propenyl. 3-fluoro-2-propenyl group, ethynyl group, 2-fluoroethynyl group, 2-propynyl group, and 3-fluoro-2propynyl group are preferable.
Preferred aromatic hydrocarbons include phenyl group, 2-fluorophenyl group, 3-fluorophenyl group, 2,4-difluorophenyl group, 2,6-difluorophenyl group, 3,5-difluorophenyl group, 2, 4 , 6-trifluorophenyl group is preferable.

Preferred aromatic heterocycles are 2-furanyl group, 3-furanyl group, 2-thiophenyl group, 3-thiophenyl group, 1-methyl-2-pyrrolyl group, and 1-methyl-3-pyrrolyl group.
Among these, a methyl group, an ethyl group, a fluoromethyl group, a trifluoromethyl group, a 2-fluoroethyl group, a 2,2,2-trifluoroethyl group, an ethenyl group, an ethynyl group, and a phenyl group are preferable.

More preferably, a methyl group, an ethyl group, and an ethynyl group are preferable.
n and m are not particularly limited as long as they are in the range described in the general formula (7), but are preferably 0 or 1, more preferably n = m = 1 or n = 1, m = 0. The molecular weight is preferably 50 or more. Moreover, Preferably it is 500 or less. If it is this range, it will be easy to ensure the solubility of the unsaturated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will fully be expressed easily.

Moreover, it is preferable that R is hydrogen, a fluorine, or an ethynyl group from both the reactivity and stability of the compound of the general formula (7). In the case of other substituents, the reactivity is lowered, and the expected properties may be lowered. Moreover, when it is halogen other than fluorine, there is a possibility that the reactivity is too high and the side reaction increases.
The number of fluorine or ethynyl groups in R is preferably within 2 in total. If the number is too large, the compatibility with the electrolytic solution may be deteriorated, and the reactivity may be too high to increase the side reaction.

Among these, n = 1 and m = 0 are preferable. When both are 0, stability deteriorates from the distortion of the ring, and there is a possibility that the reactivity becomes too high and the side reaction increases. Further, even if n = 2 or more, or n = 1, when m = 1 or more, there is a possibility that the chain is more stable than the ring and the initial characteristics may not be exhibited.
Furthermore, wherein, X and Z are, ^CR _{1 2} or O are more preferred. In cases other than these, the reactivity may be too high and side reactions may increase.

The molecular weight is more preferably 100 or more, and more preferably 200 or less. If it is this range, it will be easy to ensure further the solubility of General formula (7) with respect to a non-aqueous electrolyte solution, and the effect of this invention will be fully further easily expressed.
More preferably, R is all hydrogen. In this case, the side reaction is most likely to be suppressed while maintaining the expected characteristics. In addition, when Y is C═O or S═O, one of X and Z is O, indicating that Y is S (═O) ₂ , P (═O) —R ² , P (═O In the case of —OR ³ , it is preferable that both X and Z are O or CH ₂ , or one of X and Z is O, and the other is CH ₂ . When Y is C═O or S═O, if both X and Z are CH ₂ , the reactivity may be too high and side reactions may increase.
Specific examples of these compounds are shown below.

  Of the compounds represented by the general formula (7), the compound represented by the general formula (8) is preferable from the viewpoint of ease of industrial production.

In the above formula (8), Y represents C═O, S═O, S (═O) ₂ , P (═O) —R ² , P (═O) —OR ³ . Specific examples of these compounds having preferable conditions are shown below.

  The said compound which has a carbon-carbon triple bond may be used individually by 1 type, or may have 2 or more types together by arbitrary combinations and ratios. Moreover, the compounding quantity of the compound which has a carbon-carbon triple bond is not restrict | limited especially, unless the effect of this invention is impaired remarkably. The compounding amount of the compound having a carbon-carbon triple bond is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.1% by mass in 100% by mass of the nonaqueous electrolytic solution. Further, it is preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid. On the other hand, if the amount is too small, the effects of the present invention may not be sufficiently exerted. If the amount is too large, the resistance may increase and the output and load characteristics may decrease.

<Cyclic carbonate having an unsaturated bond excluding the carbon-carbon triple bond>
The non-aqueous electrolyte of the present invention has an unsaturated bond excluding the compound having a carbon-carbon triple bond in order to form a film on the surface of the negative electrode of the non-aqueous electrolyte battery and achieve a long battery life. A cyclic carbonate (hereinafter sometimes abbreviated as “unsaturated cyclic carbonate”) may be used.

The unsaturated cyclic carbonate is not particularly limited as long as it is a cyclic carbonate having a carbon-carbon double bond, and any unsaturated carbonate can be used. The cyclic carbonate having an aromatic ring is also included in the unsaturated cyclic carbonate.
Examples of the unsaturated cyclic carbonate include vinylene carbonates, ethylene carbonates substituted with a substituent having an aromatic ring or a carbon-carbon double bond, phenyl carbonates, vinyl carbonates, allyl carbonates, catechol carbonates, and the like. It is done.

  The vinylene carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4 , 5-diallyl vinylene carbonate and the like.

  Specific examples of ethylene carbonates substituted with an aromatic ring or a substituent having a carbon-carbon double bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, 4- Allyl-5-vinylethylene carbonate, phenylethylene carbonate, 4,5-diphenylethylene carbonate, 4-phenyl-5-vinylethylene carbonate, 4-allyl-5-phenylethylene carbonate, allylethylene carbonate, 4,5-diallylethylene Examples thereof include carbonate and 4-methyl-5-allylethylene carbonate.

  Among these, particularly preferred unsaturated cyclic carbonates include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, vinyl vinylene carbonate, 4,5-vinyl vinylene carbonate, allyl vinylene carbonate, 4,5-diallyl vinylene carbonate, Vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, 4-methyl-5-vinyl ethylene carbonate, allyl ethylene carbonate, 4,5-diallyl ethylene carbonate, 4-methyl-5-allyl ethylene carbonate, 4-allyl-5- Vinylethylene carbonate is more preferably used because it forms a stable interface protective film.

  The molecular weight of the unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 50 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the unsaturated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will fully be expressed easily. The molecular weight of the unsaturated cyclic carbonate is more preferably 80 or more, and more preferably 150 or less. The production method of the unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method.

An unsaturated cyclic carbonate may be used individually by 1 type, or may have 2 or more types by arbitrary combinations and ratios.
Moreover, the compounding quantity of unsaturated cyclic carbonate is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary. The amount of the unsaturated cyclic carbonate is 100% by mass in the non-aqueous electrolyte solution, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more. Moreover, Preferably it is 5 mass% or less, More preferably, it is 4 mass% or less, More preferably, it is 3 mass% or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid. On the other hand, if the amount is too small, the effects of the present invention may not be sufficiently exhibited. If the amount is too large, the resistance may increase and the output and load characteristics may decrease.

<Fluorinated unsaturated cyclic carbonate>
As the fluorinated cyclic carbonate, it is also preferable to use a cyclic carbonate having an unsaturated bond and a fluorine atom (hereinafter sometimes abbreviated as “fluorinated unsaturated cyclic carbonate”). The number of fluorine atoms contained in the fluorinated unsaturated cyclic carbonate is not particularly limited as long as it is 1 or more. Among them, the number of fluorine atoms is usually 6 or less, preferably 4 or less, and most preferably 1 or 2 fluorine atoms.

Examples of the fluorinated unsaturated cyclic carbonate include a fluorinated vinylene carbonate derivative, a fluorinated ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon double bond.
Fluorinated vinylene carbonate derivatives include 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-phenyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4-fluoro-5- And vinyl vinylene carbonate.

Examples of the fluorinated ethylene carbonate derivative substituted with an aromatic ring or a substituent having a carbon-carbon double bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5. -Vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate, 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4-fluoro-4
, 5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate, 4-fluoro-4-phenylethylene carbonate, 4-fluoro-5 -Phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate and the like.

  Among them, particularly preferable fluorinated unsaturated cyclic carbonates include 4-fluoro vinylene carbonate, 4-fluoro-5-methyl vinylene carbonate, 4-fluoro-5-vinyl vinylene carbonate, 4-allyl-5-fluoro vinylene carbonate, 4 -Fluoro-4-vinylethylene carbonate, 4-fluoro-4-allylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4-fluoro-5-allylethylene carbonate, 4,4-difluoro-4-vinylethylene carbonate 4,4-difluoro-4-allylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-allylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate 4-fluoro-4,5-diallylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-diallylethylene carbonate form a stable interface protective coating Therefore, it is used more suitably.

  The molecular weight of the fluorinated unsaturated cyclic carbonate is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 50 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the fluorinated cyclic carbonate with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the fluorinated unsaturated cyclic carbonate is not particularly limited, and can be produced by arbitrarily selecting a known method. The molecular weight is more preferably 100 or more, and more preferably 200 or less.

A fluorinated unsaturated cyclic carbonate may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios.
Moreover, the compounding quantity of a fluorinated unsaturated cyclic carbonate is not restrict | limited in particular, As long as the effect of this invention is not impaired remarkably, it is arbitrary. The compounding amount of the fluorinated unsaturated cyclic carbonate is usually in 100% by mass of the nonaqueous electrolytic solution, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more. Moreover, it is preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less. Within this range, the non-aqueous electrolyte secondary battery is likely to exhibit a sufficient cycle characteristics improvement effect, and the high-temperature storage characteristics are reduced, the amount of gas generated is increased, and the discharge capacity maintenance rate is reduced. Easy to avoid. On the other hand, if the amount is too small, the effects of the present invention may not be sufficiently exhibited. If the amount is too large, the resistance may increase and the output and load characteristics may decrease.

<Cyclic sulfonate ester>
In the nonaqueous electrolytic solution of the present invention, it is also preferable to use a cyclic sulfonate ester. The molecular weight of the cyclic sulfonic acid ester compound is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 100 or more and 250 or less. If it is this range, it will be easy to ensure the solubility of the cyclic sulfonic acid ester compound with respect to a non-aqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the cyclic sulfonate compound is not particularly limited, and can be produced by arbitrarily selecting a known method.

In the non-aqueous electrolyte solution of the present invention, examples of the cyclic sulfonate compound that can be used include:
1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1-methyl-1
, 3-propane sultone, 2-methyl-1,3-propane sultone, 3-methyl-1,3-propane sultone, 1,4-butane sultone, 1-fluoro-1,4-butane sultone, 2-fluoro-1, 4-butane sultone, 3-fluoro-1,4-butane sultone, 4-fluoro-1,4-butane sultone, 1-methyl-1,4-butane sultone, 2-methyl-1,4-butane sultone, 3-methyl-1, 4-butane sultone, 4-methyl-1,4-butane sultone, 1,5-pentane sultone, 1-fluoro-1,5-pentane sultone, 2-fluoro-1,5-pentane sultone, 3-fluoro-1,5 -Pentanthruton, 4-fluoro-1,5-pentanthruton, 5-fluoro-1,5-pentanthruton, 1-methyl-1,5- Monosulfonic acid such as tantalum sultone, 2-methyl-1,5-pentanthultone, 3-methyl-1,5-pentanthrutone, 4-methyl-1,5-pentanthrutone, 5-methyl-1,5-pentanthruton Ester compounds;
Disulfonate compounds such as methylene methane disulfonate, ethylene methane disulfonate, ethylene ethane disulfonate;
Etc.

  Among these, 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro-1,3-propane sultone, 1,4-butane sultone, Methylene methane disulfonate and ethylene methane disulfonate are preferable from the viewpoint of improving storage characteristics. 1,3-propane sultone, 1-fluoro-1,3-propane sultone, 2-fluoro-1,3-propane sultone, 3-fluoro -1,3-propane sultone is more preferred.

  It is also preferable to use a cyclic sulfonic acid ester having a carbon-carbon double bond. Examples of the cyclic sulfonic acid ester having a carbon-carbon double bond include 1-propene-1,3-sultone, 2-propene-1,3-sultone, 1-fluoro-1-propene-1,3-sultone, 2 -Fluoro-1-propene-1,3-sultone, 3-fluoro-1-propene-1,3-sultone, 1-methyl-1-propene-1,3-sultone, 2-methyl-1-propene-1 , 3-sultone, 3-methyl-1-propene-1,3-sultone, 1-butene-1,4-sultone, 2-butene-1,4-sultone, 3-butene-1,4-sultone, 1 -Fluoro-1-butene-1,4-sultone, 2-fluoro-1-butene-1,4-sultone, 3-fluoro-1-butene-1,4-sultone, 4-fluoro-1-butene-1 , 4-sultone, 1-methyl -1-butene-1,4-sultone, 2-methyl-1-butene-1,4-sultone, 3-methyl-1-butene-1,4-sultone, 4-methyl-1-butene-1,4 -Sultone, etc. can be mentioned.

Of these, 1-propene-1,3-sultone, 1-butene-1,4-sultone, 2-butene-1,4-sultone, and 3-butene-1,4-sultone are more preferable.
A cyclic sulfonic acid ester compound may be used individually by 1 type, and may have 2 or more types by arbitrary combinations and ratios.
There is no restriction | limiting in the compounding quantity of the cyclic sulfonate ester compound with respect to the whole non-aqueous electrolyte solution of this invention, Although it is arbitrary unless the effect of this invention is impaired remarkably, Usually, it is 0.8 with respect to the non-aqueous electrolyte solution of this invention. 001% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Let When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

<Compound having a cyano group>
In the nonaqueous electrolytic solution of the present invention, it is also preferable to use a compound having a cyano group. Here, the compound having a cyano group is not particularly limited as long as it is a compound having a cyano group in the molecule, but a compound represented by the general formula (9) is more preferable.

In the general formula (9), T represents an organic group composed of an atom selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom and a halogen atom, and U represents a substituent. And a V-valent organic group having 1 to 10 carbon atoms which may have a group. V is an integer of 1 or more, and when V is 2 or more, T may be the same or different.
The molecular weight of the compound having a cyano group is not particularly limited and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 50 or more, more preferably 80 or more, still more preferably 100 or more, and 200 or less. If it is this range, it will be easy to ensure the solubility of the compound which has a cyano group with respect to nonaqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the compound having a cyano group is not particularly limited, and can be produced by arbitrarily selecting a known method.

Specific examples of the compound represented by the general formula (9) include, for example,
Acetonitrile, propionitrile, butyronitrile, isobutyronitrile, valeronitrile, isovaleronitrile, lauronitrile, 2-methylbutyronitrile, 2,2-dimethylbutyronitrile, hexanenitrile, cyclopentanecarbonitrile, cyclohexanecarbonitrile , Acrylonitrile, methacrylonitrile, crotononitrile, 3-methylcrotononitrile, 2-methyl-2-butenenitryl, 2-pentenenitrile, 2-methyl-2-pentenenitrile, 3-methyl-2-pentenenitrile 2-hexenenitrile, fluoroacetonitrile, difluoroacetonitrile, trifluoroacetonitrile, 2-fluoropropionitrile, 3-fluoropropionitrile, 2,2-difluoropropionitrile, 2,3 Difluoropropionitrile, 3,3-difluoropropionitrile, 2,2,3-trifluoropropionitrile, 3,3,3-trifluoropropionitrile, 3,3′-oxydipropionitrile, 3,3 ′ -Compounds having one cyano group such as thiodipropionitrile, 1,2,3-propanetricarbonitrile, 1,3,5-pentanetricarbonitrile, pentafluoropropionitrile;

Malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, azeronitrile, sebaconitrile, undecandinitrile, dodecandinitrile, methylmalononitrile, ethylmalononitrile, i-propylmalononitrile, t-butylmalononitrile, methylsk Sinonitrile, 2,2-dimethylsuccinonitrile, 2,3-dimethylsuccinonitrile, trimethylsuccinonitrile, tetramethylsuccinonitrile, 3,3 ′-(ethylenedioxy) dipropionitrile, 3,3 ′ -A compound having two cyano groups such as (ethylenedithio) dipropionitrile;
Compounds having three cyano groups such as 1,2,3-tris (2-cyanoethoxy) propane and tris (2-cyanoethyl) amine;

Cyanate compounds such as methyl cyanate, ethyl cyanate, propyl cyanate, butyl cyanate, pentyl cyanate, hexyl cyanate, heptyl cyanate;
Methyl thiocyanate, ethyl thiocyanate, propyl thiocyanate, butyl thiocyanate, pentyl thiocyanate, hexyl thiocyanate, heptyl thiocyanate, methanesulfonyl cyanide, ethanesulfonyl cyanide, propanesulfonyl cyanide, butanesulfonyl cyanide, pentanesulfonyl cyanide, hexanesulfonyl cyanide , Heptanesulfonylcyanide, methylsulfurocyanidate, ethylsulfurocyanidate, propylsulfurocyanidate, butylsulfurocyanidate, pentylsulfurocyanidate, hexylsulfurocyanidate, heptylsulfur Sulfur-containing compounds such as frocyanidates;

Cyanodimethylphosphine, cyanodimethylphosphine oxide, methyl cyanomethylphosphinate, methyl cyanomethylphosphinate, dimethylphosphinic acid cyanide, dimethylphosphinic acid cyanide, dimethylphosphonic acid dimethyl, cyanophosphonic acid dimethyl, methylphosphonic acid cyanomethyl, methylphosphonic acid Phosphorus-containing compounds such as cyanomethyl acid, cyanodimethyl phosphate, cyanodimethyl phosphite;
Etc.

Of these,
Acetonitrile, propionitrile, butyronitrile, i-butyronitrile, valeronitrile, i-valeronitrile, lauronitrile, crotononitrile, 3-methylcrotononitrile, malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimonitrile, suberonitrile, Azeronitrile, sebaconitrile, undecandinitrile, and dodecanedinitrile are preferable from the viewpoint of improving the storage characteristics, and cyano such as malononitrile, succinonitrile, glutaronitrile, adiponitrile, pimelonitrile, suberonitrile, azeronitrile, sebacononitrile, undecandinitrile, dodecanedinitrile, etc. A compound having two groups is more preferred.

The compound which has a cyano group may be used individually by 1 type, and may have 2 or more types together by arbitrary combinations and ratios.
The compounding amount of the compound having a cyano group with respect to the entire non-aqueous electrolyte solution of the present invention is not limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. 001% by mass or more, preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and usually 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less. Let When the above range is satisfied, effects such as output characteristics, load characteristics, low temperature characteristics, cycle characteristics, and high temperature storage characteristics are further improved.

<Compound having an isocyanato group>
It is also preferable to use an isocyanate compound in the nonaqueous electrolytic solution of the present invention. Here, the compound having an isocyanato group is not particularly limited as long as it is a compound having an isocyanato group in the molecule, but as a specific example,
Isocyanatomethane, 1-isocyanatoethane, 1-isocyanato-2-methoxyethane, 3-isocyanato-1-propene, isocyanatocyclopropane, 2
-Isocyanatopropane, 1-isocyanatopropane, 1-isocyanato-3-methoxypropane, 1-isocyanato-3-ethoxypropane, 2-isocyanato-2-methylpropane, 1-isocyanatobutane, 2-isocyanatobutane,
1-isocyanato-4-methoxybutane, 1-isocyanato-4-ethoxybutane, methyl isocyanatoformate, isanatocyclopentane, 1-isocyanatopentane, 1-isocyanato-5-methoxypentane, 1-isocyanato-5
-Ethoxypentane, 2- (isocyanatomethyl) furan, isocyanatocyclohexane, 1-isocyanatohexane, 1-isocyanato-6-methoxyhexane, 1-isocyanato-6-ethoxyhexane, ethyl isocyanatoacetate, isocyanatocyclopentane , Isocyanatomethyl (cyclohexane), monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, 1, 3-diisocyanatopropane, 1,4-diisocyanato-2-but , 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3-difluorobutane, 1,5-diisocyanato-2-pentene, 1,5-diisocyanato-2-methylpentane, 1,6 -Diisocyanato-2-hexene, 1,6-diisocyanato-3-hexene, 1,6-diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate 1,2-bis (isocyanatomethyl) cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-diisocyanatocyclohexane, 1,3- Diisocyanatocyclohexane, 1,4 Diisocyanatocyclohexane, dicyclohexylmethane-1,1′-diisocyanate, dicyclohexylmethane-2,2′-diisocyanate, dicyclohexylmethane-3,3′-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, isophorone diisocyanate, Biuret, isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the basic structures of the formulas (10-1) to (10-4) are mentioned (in the formula, R and R ′ are arbitrary, respectively) Hydrocarbon group).

  Among the compounds having an isocyanato group, a compound represented by the general formula (10-5) is preferable in order to form a good protective film.

(In the formula, A represents a C 1-20 organic group composed of an atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom; n ′ is an integer of 2 or more.)
The organic group having 1 to 20 carbon atoms composed of an atom selected from the group consisting of a hydrogen atom, a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, and a halogen atom is composed of a carbon atom and a hydrogen atom. The organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, or a halogen atom in addition to the organic group to be formed is meant. An organic group which may contain a nitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, or a halogen atom is an organic group in which a part of the carbon atoms of the skeleton is substituted with these atoms, or these atoms. It is meant to include an organic group having a configured substituent.

  The molecular weight of the compound represented by the general formula (10-5) is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The molecular weight is preferably 80 or more, more preferably 115 or more, still more preferably 180 or more, and is 400 or less, more preferably 270 or less. If it is this range, it will be easy to ensure the solubility of the compound represented with General formula (10-5) with respect to nonaqueous electrolyte solution, and the effect of this invention will be easy to be expressed. The production method of the compound represented by the general formula (10-5) is not particularly limited, and can be produced by arbitrarily selecting a known method.

As a specific example of A in the general formula (10-5), for example,
Alkylene group or derivative thereof, alkenylene group or derivative thereof, cycloalkylene group or derivative thereof, alkynylene group or derivative thereof, cycloalkenylene group or derivative thereof, arylene group or derivative thereof, carbonyl group or derivative thereof, sulfonyl group or derivative thereof, Sulfinyl group or derivative thereof, phosphonyl group or derivative thereof, phosphinyl group or derivative thereof, amide group or derivative thereof, imide group or derivative thereof, ether group or derivative thereof, thioether group or derivative thereof, borinic acid group or derivative thereof, borane Group or a derivative thereof.

  Among these, an alkylene group or a derivative thereof, an alkenylene group or a derivative thereof, a cycloalkylene group or a derivative thereof, an alkynylene group or a derivative thereof, an arylene group or a derivative thereof is preferable from the viewpoint of improving battery characteristics. More preferably, B is an organic group having 2 to 14 carbon atoms which may have a substituent.

Specific examples of the compound represented by the general formula (10-5) include, for example, monomethylene diisocyanate, dimethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene. Diisocyanate, nonamethylene diisocyanate, decamethylene diisocyanate, 1,3-diisocyanatopropane, 1,4-diisocyanato-2-butene, 1,4-diisocyanato-2-fluorobutane, 1,4-diisocyanato-2,3- Difluorobutane, 1,5-diisocyanato-2-pentene, 1,5-diisocyanato-2-methylpentane, 1,6-diisocyanato-2-hexene, 1,6-diisocyanate Nato-3-hexene, 1,6-diisocyanato-3-fluorohexane, 1,6-diisocyanato-3,4-difluorohexane, toluene diisocyanate, xylene diisocyanate, tolylene diisocyanate, 1,2-bis (isocyanatomethyl) Cyclohexane, 1,3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, 1,2-diisocyanatocyclohexane, 1,3-diisocyanatocyclohexane, 1,4-diisocyanate Natocyclohexane, dicyclohexylmethane-1,1′-diisocyanate, dicyclohexylmethane-2,2′-diisocyanate, dicyclohexylmethane-3,3′-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, isophoro Diisocyanates, and biurets, isocyanurates, adducts, and bifunctional types of modified polyisocyanates represented by the basic structures of formulas (10-1) to (10-4), respectively (wherein R and R ′ is an arbitrary hydrocarbon group).

Of these, trimethylene diisocyanate, hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane-4,4 ′
-Diisocyanate, biuret, isocyanurate, adduct, and bifunctional type modified polyisocyanate represented by the basic structures of formulas (10-1) to (10-4) are preferred from the viewpoint of forming a more stable film.

Moreover, the isocyanate compound mentioned above may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
There is no restriction | limiting in the compounding quantity of the compound represented by General formula (10-5) with respect to the whole non-aqueous electrolyte of this invention, and it is arbitrary unless the effect of this invention is impaired remarkably, The non-aqueous electrolyte of this invention Is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.2% by mass or more, and usually 5% by mass or less, preferably Is 4.0% by mass or less, more preferably 3.0% by mass or less, and still more preferably 2% by mass or less. When the content is within the above range, durability such as cycle and storage can be improved, and the effects of the present invention can be sufficiently exerted. <Other auxiliary agents>
Other known auxiliary agents can be used in the non-aqueous electrolyte solution of the present invention. Other auxiliaries include carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate, methoxyethyl-methyl carbonate; succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, anhydrous Carboxylic anhydrides such as itaconic acid, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride; 2,4,8,10-tetraoxaspiro [5.5 ] Spiro compounds such as undecane, 3,9-divinyl-2,4,8,10-tetraoxaspiro [5.5] undecane; ethylene sulfite, methyl fluorosulfonate, ethyl fluorosulfonate, methyl methanesulfonate, Ethyl methanesulfonate, ethanesulfo Sulfur-containing compounds such as methyl acid, ethyl ethanesulfonate, busulfan, sulfolene, diphenylsulfone, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide; 1-methyl-2-pyrrolidinone, 1-methyl- Nitrogen-containing compounds such as 2-piperidone, 3-methyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone and N-methylsuccinimide; hydrocarbon compounds such as heptane, octane, nonane, decane and cycloheptane; Fluorinated aromatic compounds such as fluorobenzene, difluorobenzene, hexafluorobenzene, benzotrifluoride; methyl dimethyl phosphinate, ethyl dimethyl phosphinate, ethyl diethyl phosphinate, trimethyl phosphonoformate, triethyl phosphine Noforumeto, trimethyl phosphonoacetate, triethyl phosphonoacetate, trimethyl-3-phosphono propionate, phosphorus-containing compounds such as triethyl-3-phosphono propionate. These may be used alone or in combination of two or more. By adding these auxiliaries, capacity maintenance characteristics and cycle characteristics after high temperature storage can be improved.

  Among these, ethylene sulfite, methyl fluorosulfonate, methyl methanesulfonate, methyl ethanesulfonate, ethyl methanesulfonate, busulfan, 1,4-butanediol bis (2,2,2-trifluoroethanesulfonate), etc. This sulfur-containing compound is particularly preferable because it has a large effect of improving capacity retention characteristics and cycle characteristics after high-temperature storage.

  The blending amount of other auxiliary agents is not particularly limited, and is arbitrary as long as the effects of the present invention are not significantly impaired. The other auxiliary agent is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and further preferably 0.2% by mass or more in 100% by mass of the non-aqueous electrolyte solution. It is at most 3% by mass, more preferably at most 3% by mass, even more preferably at most 1% by mass. Within this range, the effects of other auxiliaries can be sufficiently exhibited, and it is easy to avoid a situation in which battery characteristics such as high-load discharge characteristics deteriorate.

  The non-aqueous electrolyte solution described above includes those existing inside the non-aqueous electrolyte battery according to the present invention. Specifically, the components of the non-aqueous electrolyte solution such as lithium salt, solvent, and auxiliary agent are separately synthesized, and the non-aqueous electrolyte solution is prepared from what is substantially isolated by the method described below. In the case of a nonaqueous electrolyte solution in a nonaqueous electrolyte battery obtained by pouring into a separately assembled battery, the components of the nonaqueous electrolyte solution of the present invention are individually placed in the battery, In order to obtain the same composition as the non-aqueous electrolyte solution of the present invention by mixing in a non-aqueous electrolyte battery, the compound constituting the non-aqueous electrolyte solution of the present invention is further generated in the non-aqueous electrolyte battery. The case where the same composition as the aqueous electrolyte is obtained is also included.

2. Positive electrode <Positive electrode active material>
The positive electrode active material used for the positive electrode is described below.
(composition)
The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions. However, a transition metal compound containing at least one or more metal elements in addition to Li and Mn, at least Li, Ni, It contains at least one selected from the group consisting of transition metal compounds containing Co and / or Mn, and mixed valence transition metal compounds containing one or more transition metal elements each having an average oxidation number of +4 and +3. Is preferred.

Specific examples of the transition metal compound include lithium transition metal compounds represented by the following general formulas (i) to (iii).
Li [Li _a M _x Mn _2−x−a ] O _{4 + δ} (i)
(In formula (i), 0 ≦ a ≦ 0.3, 0.4 <x <1.1, −0.5 <δ <0.5 is satisfied, and M is Ni, Cr, Fe, Co and Cu. Represents at least one of transition metals selected from
Li _x M1 _y M2 _z O _2-δ (ii)
(In the formula (ii), 1 ≦ x ≦ 1.3, 0 ≦ y ≦ 1, 0 ≦ z ≦ 0.3, −0.1 ≦ δ ≦ 0.1 is satisfied, and M1 represents Ni, Co, and / or Or M2 represents Fe, Cr, V, Ti, Cu, Ga, Bi, Sn, B, P, Zn, Mg, Ge, Nb, W, Ta, Be, Al, Ca, Sc and Zr. Represents at least one element selected.)
αLi ₂ MO _3. (1-α) LiM′O ₂ (iii)
(In the formula (iii), 0 <α <1 is satisfied, M is at least one metal element having an average oxidation number of +4, and M ′ is at least one metal element having an average oxidation number of +3. Represents.)

As the transition metal of the lithium transition metal compound represented by the general formula (i), Ni, Cr, Mn, Fe, Co and Cu are preferable, and specific examples include LiMn ₂ O ₄ , Li ₂ MnO ₄ and Li _{1 + a.} Lithium-manganese composite oxides such as Mn ₂ O ₄ (a; 0 <a ≦ 3.0), LiMn _x Ni _2−x O ₄ , Li _{1 + a} Mn _1.5 Ni _0.5 O ₄ (a; 0 < a ≦ 3.
And lithium / nickel / manganese composite oxides such as 0).

V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable as the transition metal of the lithium transition metal compound represented by the general formula (ii), and specific examples include lithium / cobalt such as LiCoO _2. Examples include composite oxides, lithium / manganese composite oxides such as LiMnO ₂ , lithium / nickel composite oxides such as LiNiO ₂ , and the like.

Further, some of the transition metal atoms that are the main components of these lithium transition metal composite oxides are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, and Si. Specific examples include lithium-nickel-cobalt-aluminum composite oxides, lithium-cobalt-nickel composite oxides, lithium-cobalt-manganese composite oxides, lithium- Nickel / manganese composite oxide, lithium / nickel / cobalt / manganese composite oxide, and the like can be given. Among these, lithium / nickel / manganese composite oxide and lithium / nickel / cobalt / manganese composite oxide are preferable because of good battery characteristics. For _{example, LiNi x Mn 1-x O} 2, LiNi x Co y Al 1-x-y O 2, LiNi x Co y Mn z O 2 (x + y + z = 1), LiMn
_{x Al 2-x O 4,} αLi 2 MO 3 · (1-α) LiM'O 2 (0 <α <1), Li 2 MPO 4 F, Li 2 MSiO 4, LiMPO 4 (M = Fe, Ni, Mn, Co) and the like.

Specific examples of the substituted _one include, for example, Li _{1 + a} Ni _0.5 Mn _0.5 O ₂ , L
i _{1 + a} Ni _0.8 Co _0.2 O ₂ , Li _{1 + a} Ni _0.85 Co _0.10 Al _0.05 O ₂ , Li _{1 + a} Ni _0.33 Co _0.33 Mn _0.33 O ₂ , Li _{1 + a} Ni _0.45 Mn _0.45 Co _0.1 O ₂ , Li _{1 + a} Ni _0.475 Mn _0.475 Co _0.05 O ₂ , Li _{1 + a} Mn _1.8 Al _0.2 O ₄ , xLi ₂ MnO _3. ( 1-x) Li _{1 + a} MO ₂ (M = transition metal, for example, a metal selected from the group consisting of Li, Ni, Mn, and Co) (a; 0 <a ≦ 3.0). The ratio of these substituted metal elements in the composition formula is appropriately adjusted depending on the relationship between the battery characteristics of the battery using the element and the cost of the material.

_{Further, αLi 2 MO 3 · (1} -α) LiM'O 2 as represented by the following general formula (iii) can be cited as the lithium transition metal-based compound. Where M is a number satisfying 0 <α <1, and M is at least one metal element having an average oxidation number of +4, preferably selected from the group consisting of Mn, Zr, Ti, Ru, Re, and Pt And at least one metal element selected from the group consisting of Mn, Zr and Ti. M ′ is at least one metal element having an average oxidation number of +3, preferably at least one metal element selected from the group consisting of V, Mn, Fe, Co and Ni, more preferably It is at least one metal element selected from the group consisting of Mn, Co and Ni.

Among these positive electrode active materials, it is preferable to use the above general formula (i) and the above general formula (iii) as a positive electrode for a battery having a high open circuit voltage between battery terminals, more preferably the above general formula (i). It is preferable to use from the viewpoint of the stability of the positive electrode active material. Specifically, of the lithium transition metal-based compound represented by the general formula _{(i), LiMn x Ni 2} -x O 4, Li 1 + a
Lithium / nickel / manganese composite oxides such as Mn _1.5 Ni _0.5 O ₄ (a; 0 <a ≦ 3.0) are preferred from the viewpoints of stability of the positive electrode active material and charge capacity.

In the present invention, although not particularly limited, a lithium-containing transition metal phosphate compound is also preferably used as the positive electrode active material. Examples of the transition metal of the lithium-containing transition metal phosphate compound include V, Ti, Cr, Mn, and Fe. , Co, Ni, Cu and the like are preferable. Specific examples include, for example, iron phosphates such as LiFePO ₄ , Li ₃ Fe ₂ (PO ₄ ) ₃ and LiFeP ₂ O ₇ , cobalt phosphates such as LiCoPO ₄ , Some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si. And the like substituted with other elements.

  In addition, it is preferable to include lithium phosphate in the positive electrode active material because continuous charge characteristics are improved. Although there is no restriction | limiting in the use of lithium phosphate, It is preferable to mix and use the said positive electrode active material and lithium phosphate. The lower limit of the amount of lithium phosphate used is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, and still more preferably 0.5% by mass with respect to the total of the positive electrode active material and lithium phosphate. %, And the upper limit is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 5% by mass or less.

(Surface coating)
Moreover, you may use what the substance of the composition different from this adhered to the surface of the said positive electrode active material. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.

  For example, these surface adhering substances are dissolved or suspended in a solvent, impregnated and added to the positive electrode active material, and dried. After the surface adhering substance precursor is dissolved or suspended in a solvent and impregnated and added to the positive electrode active material, It can be made to adhere to the surface of the positive electrode active material by a method of reacting by heating or the like, a method of adding to the positive electrode active material precursor and firing simultaneously. In addition, when making carbon adhere, the method of making carbonaceous adhere mechanically later in the form of activated carbon etc. can also be used, for example.

The amount of the surface adhering substance is, in terms of mass with respect to the positive electrode active material, preferably 0.1 ppm or more, more preferably 1 ppm or more, further preferably 10 ppm or more, and the upper limit, preferably 20% or less, more preferably, as the lower limit. Is used at 10% or less, more preferably 5% or less. The surface adhering substance can suppress the oxidation reaction of the electrolyte solution on the surface of the positive electrode active material, and can improve the battery life. If it is too high, the resistance may increase in order to inhibit the entry and exit of lithium ions.
In the present invention, a “positive electrode active material” includes a material having a composition different from that of the positive electrode active material.

(shape)
Examples of the shape of the particles of the positive electrode active material include a lump shape, a polyhedron shape, a sphere shape, an oval sphere shape, a plate shape, a needle shape, and a column shape as conventionally used. Moreover, primary particles may aggregate to form secondary particles.
(Tap density)
The tap density of the positive electrode active material is preferably 0.5 g / cm ³ or more, more preferably 0.8 g / cm ³ or more, and further preferably 1.0 g / cm ³ or more. If the tap density of the positive electrode active material is lower than the lower limit, the amount of the required dispersion medium increases when the positive electrode active material layer is formed, and the required amount of the conductive material and the binder increases, so The filling rate of the active material is restricted, and the battery capacity may be restricted. By using a complex oxide powder having a high tap density, a high-density positive electrode active material layer can be formed. In general, the tap density is preferably as large as possible, and there is no particular upper limit. The upper limit is preferably 3.0 g / cm ³ or less, more preferably 2.7 g / cm ³ or less, and even more preferably 2.5 g / cm ³ or less.

  In the present invention, the tap density is defined as the powder packing density (tap density) g / cc when 5 to 10 g of the positive electrode active material powder is put in a 10 ml glass measuring cylinder and tapped 200 times with a stroke of about 20 mm. Ask.

(Median diameter d ₅₀ )
The median diameter d _{50 of the} lithium / nickel / cobalt / manganese composite oxide particles that can be contained in the positive electrode active material (secondary particle diameter when the primary particles are aggregated to form secondary particles) is preferably 0.3 μm or more, more preferably 0.5 μm or more, further preferably 0.8 μm or more, most preferably 1.0 μm or more, and the upper limit is preferably 30 μm or less, more preferably 27 μm or less, and even more preferably 25 μm or less. Most preferably, it is 22 μm or less. If the lower limit is not reached, a high tap density product may not be obtained. If the upper limit is exceeded, it takes time to diffuse lithium in the particles. When a conductive material, a binder, or the like is slurried with a solvent and applied as a thin film, problems such as streaking may occur. Here, different median size d ₅₀ by mixing 2 or more kinds of positive electrode active material with, it is possible to further improve the filling property at the time of the positive electrode creation.

In the present invention, the median diameter d ₅₀ is measured by a known laser diffraction / scattering particle size distribution measuring apparatus. When LA-920 manufactured by HORIBA is used as a particle size distribution meter, a 0.1% by mass sodium hexametaphosphate aqueous solution is used as a dispersion medium for measurement, and a measurement refractive index of 1.24 is set after ultrasonic dispersion for 5 minutes. Measured.

(Median diameter d ₉₀ )
The median diameter of the lithium / nickel / manganese composite oxide that can be contained in the positive electrode active material is usually 2 μm or more, preferably 2.5 μm or more, more preferably 3 μm or more, still more preferably 3.5 μm or more, and most preferably 4 μm or more. Usually, it is 60 μm or less, preferably 50 μm or less, more preferably 40 μm or less, still more preferably 30 μm or less, and most preferably 20 μm or less. When the median diameter is less than this lower limit, there is a possibility that a problem occurs in the coating property at the time of forming the positive electrode active material layer, and when the upper limit is exceeded, battery performance may be deteriorated.

The 90% cumulative diameter (D ₉₀ ) of secondary particles of lithium / nickel / manganese composite oxide that can be contained in the positive electrode active material is usually 30 μm or less, preferably 25 μm or less, more preferably 22 μm or less, and most preferably 20 μm. In the following, it is usually 3 μm or more, preferably 4 μm or more, more preferably 5 μm or more, and most preferably 6 μm or more. If the 90% cumulative diameter (D ₉₀ ) exceeds the above upper limit, the battery performance may be deteriorated, and if it is less than the lower limit, there is a possibility of causing a problem in the coating property when forming the positive electrode active material layer.

In the present invention, the median diameter and the 90% cumulative diameter (D ₉₀ ) as the average particle diameter are set to a refractive index of 1.60 by a known laser diffraction / scattering particle size distribution measuring device, and the particle diameter standard is determined. Measured as a volume reference. In this invention, it measured using 0.1 weight% sodium hexametaphosphate aqueous solution as a dispersion medium used in the case of a measurement.

(Average primary particle size)
In the lithium-nickel-cobalt-manganese composite oxide that can be contained in the positive electrode active material, when primary particles are aggregated to form secondary particles, the average primary particle size of the positive electrode active material is preferably Is 0.05 μm or more, more preferably 0.1 μm or more, further preferably 0.2 μm or more, and the upper limit is preferably 5 μm or less, more preferably 4 μm or less, still more preferably 3 μm or less, and most preferably 2 μm or less. is there. If the above upper limit is exceeded, it is difficult to form spherical secondary particles, which adversely affects the powder filling property, or the specific surface area is greatly reduced, so that there is a high possibility that battery performance such as output characteristics will deteriorate. is there. On the other hand, when the value falls below the lower limit, there is a case where problems such as inferior reversibility of charge / discharge are usually caused because crystals are not developed.

  The average diameter (average primary particle diameter) of the lithium / nickel / manganese composite oxide that can be contained in the positive electrode active material is not particularly limited, but the lower limit is preferably 0.1 μm or more, more preferably 0.2 μm or more. The upper limit is preferably 3 μm or less, more preferably 2 μm or less, still more preferably 1.5 μm or less, and most preferably 1.2 μm or less. If the average primary particle size exceeds the above upper limit, it may adversely affect the powder filling property or the specific surface area will decrease, which may increase the possibility that the battery performance such as rate characteristics and output characteristics will decrease. There is sex. If the lower limit is not reached, there is a possibility that problems such as inferior reversibility of charge / discharge due to the undeveloped crystals.

  In the present invention, the primary particle diameter is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for any 50 primary particles and obtained by taking the average value. It is done.

(BET specific surface area)
The BET specific surface area of the lithium / nickel / cobalt / manganese composite oxide that can be contained in the positive electrode active material is preferably 0.1 m ² / g or more, more preferably 0.2 m ² / g or more, and still more preferably 0.3 m. ² / g or more, and the upper limit is 50 m ² / g or less, preferably 40
m ² / g or less, more preferably 30 m ² / g or less. If the BET specific surface area is smaller than this range, the battery performance tends to be lowered. If the BET specific surface area is larger, the tap density is difficult to increase, and a problem may occur in applicability when forming the positive electrode active material layer.

Lithium-nickel-manganese composite oxide may be included in the positive electrode active material also, BET specific surface area is usually 0.2 m ² / g or more, preferably 0.3 m ² / g or more, more preferably 0.35 m ² / g or more, most preferably 0.4 m ² / g or more, usually 3 m ² / g or less, preferably 2.5 m ² / g or less, more preferably 2 m ² / g or less, most preferably 1.5 m ² / g. It is as follows. If the BET specific surface area is smaller than this range, the battery performance tends to be lowered. If the BET specific surface area is larger, the bulk density is difficult to increase, and the energy density as the positive electrode active material may not be improved.

  The BET specific surface area can be measured by a known BET type powder specific surface area measuring device. In the present invention, an OMS Riken: AMS8000 type automatic powder specific surface area measuring device was used, nitrogen was used as an adsorption gas, and helium was used as a carrier gas. Specifically, the powder sample was heated and deaerated with a mixed gas at a temperature of 150 ° C., then cooled to liquid nitrogen temperature to adsorb the mixed gas, and then heated to room temperature with water to be adsorbed. Nitrogen gas was desorbed, the amount was detected by a heat conduction detector, and the specific surface area of the sample was calculated therefrom.

(Method for producing positive electrode active material)
As a manufacturing method of the positive electrode active material, a general method is used as a manufacturing method of the inorganic compound. In particular, various methods are conceivable for preparing a spherical or elliptical active material. For example, a transition metal source material is dissolved or pulverized and dispersed in a solvent such as water, and the pH is adjusted while stirring. And a spherical precursor is prepared and recovered, and dried as necessary. Then, a Li source such as LiOH, Li ₂ CO ₃ , LiNO ₃ is added, and the active material is obtained by baking at a high temperature. . Alternatively, a lithium compound, at least one transition metal compound selected from Mn, Ni, Cr, Fe, Co and Cu, and the additive of the present invention are pulverized in a liquid medium, and these are uniformly dispersed. A lithium transition metal system for a positive electrode material for a lithium secondary battery according to the present invention comprising a slurry preparation step for obtaining a slurry, a spray drying step for spray drying the obtained slurry, and a firing step for firing the obtained spray dried body It is preferably produced by a method for producing a compound.

For the production of the positive electrode, the positive electrode active material may be used alone, or one or more of different compositions may be used in any combination or ratio. A preferred combination in this case is a combination of LiCoO ₂ and LiMn ₂ O ₄ such as LiNi _0.33 Co _0.33 Mn _0.33 O ₂ or a part of Mn substituted with another transition metal or the like. Or a combination with LiCoO ₂ or a part of this Co substituted with another transition metal or the like.

<Configuration and manufacturing method of positive electrode>
The structure of the positive electrode will be described below. In the present invention, the positive electrode can be produced by forming a positive electrode active material layer containing a positive electrode active material and a binder on a current collector. Manufacture of the positive electrode using a positive electrode active material can be performed by a conventional method. That is, a positive electrode active material and a binder, and if necessary, a conductive material and a thickener mixed in a dry form into a sheet form are pressure-bonded to the positive electrode current collector, or these materials are liquid media A positive electrode can be obtained by forming a positive electrode active material layer on the current collector by applying it to a positive electrode current collector and drying it as a slurry by dissolving or dispersing in a slurry.

  The content of the positive electrode active material in the positive electrode active material layer is preferably 80% by mass or more, more preferably 82% by mass or more, and particularly preferably 84% by mass or more. Moreover, an upper limit becomes like this. Preferably it is 99 mass% or less, More preferably, it is 98 mass% or less. If the content of the positive electrode active material in the positive electrode active material layer is low, the electric capacity may be insufficient. Conversely, if the content is too high, the strength of the positive electrode may be insufficient.

The positive electrode active material layer obtained by coating and drying is preferably consolidated by a hand press, a roller press or the like in order to increase the packing density of the positive electrode active material. The density of the positive electrode active material layer is preferably 1.5 g / cm ³ or more as a lower limit, more preferably 2 g / cm ³ , still more preferably 2.2 g / cm ³ or more, and the upper limit is preferably 5 g / cm 3. ^{It is 3} or less, more preferably 4.5 g / cm ³ or less, and further preferably 4 g / cm ³ or less. If it exceeds this range, the permeability of the electrolyte solution to the vicinity of the current collector / active material interface decreases, and the charge / discharge characteristics particularly at a high current density decrease, and a high output may not be obtained. On the other hand, if it is lower, the conductivity between the active materials is lowered, the battery resistance is increased, and a high output may not be obtained.

(Conductive material)
A known conductive material can be arbitrarily used as the conductive material. Specific examples include metal materials such as copper and nickel; graphite such as natural graphite and artificial graphite (graphite); carbon black such as acetylene black; and carbon materials such as amorphous carbon such as needle coke. In addition, these may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. The conductive material is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more in the positive electrode active material layer, and the upper limit is usually 50% by mass or less, preferably It is used so as to contain 30% by mass or less, more preferably 15% by mass or less. If the content is lower than this range, the conductivity may be insufficient. Conversely, if the content is higher than this range, the battery capacity may decrease.

(Binder)
The binder used in the production of the positive electrode active material layer is not particularly limited, and in the case of the coating method, any material that can be dissolved or dispersed in the liquid medium used during electrode production may be used. Resin polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, nitrocellulose; SBR (styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), fluorine rubber, isoprene rubber , Rubber polymers such as butadiene rubber and ethylene-propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof, EPDM (ethylene / propylene / diene terpolymer), styrene / ethylene / butadiene / Ethylene copolymer, styrene Thermoplastic elastomeric polymer such as isoprene / styrene block copolymer or hydrogenated product thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate, ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer Soft resinous polymers such as polymers; Fluoropolymers such as polyvinylidene fluoride (PVdF), polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymers; alkali metal ions (especially lithium ions) And a polymer composition having ion conductivity. In addition, these substances may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The ratio of the binder in the positive electrode active material layer is usually 0.1% by mass or more, preferably 1% by mass or more, more preferably 1.5% by mass or more, and the upper limit is usually 80% by mass or less, preferably Is 60% by mass or less, more preferably 40% by mass or less, and most preferably 10% by mass or less. When the ratio of the binder is too low, the positive electrode active material cannot be sufficiently retained and the positive electrode has insufficient mechanical strength, which may deteriorate battery performance such as cycle characteristics. On the other hand, if it is too high, battery capacity and conductivity may be reduced.

(Slurry forming solvent)
As the solvent for forming the slurry, the positive electrode active material, the conductive material, the binder, and a solvent that can dissolve or disperse the thickener that is used as necessary are particularly suitable for the type. There is no restriction, and either an aqueous solvent or an organic solvent may be used. Examples of the aqueous medium include water, a mixed medium of alcohol and water, and the like. Examples of the organic medium include aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone. Esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine and N, N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide and tetrahydrofuran (THF); N-methylpyrrolidone (NMP) Amides such as dimethylformamide and dimethylacetamide; and aprotic polar solvents such as hexamethylphosphalamide and dimethylsulfoxide.

  In particular, when an aqueous medium is used, it is preferable to make a slurry using a thickener and a latex such as styrene-butadiene rubber (SBR). A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios. When a thickener is further added, the ratio of the thickener to the active material is 0.1% by mass or more, preferably 0.2% by mass or more, more preferably 0.3% by mass or more. The upper limit is 5% by mass or less, preferably 3% by mass or less, more preferably 2% by mass or less. Below this range, applicability may be significantly reduced. If it exceeds, the ratio of the active material in the positive electrode active material layer may decrease, and there may be a problem that the capacity of the battery decreases and a problem that the resistance between the positive electrode active materials increases.

(Current collector)
The material of the positive electrode current collector is not particularly limited, and a known material can be arbitrarily used. Specific examples include metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum; and carbon materials such as carbon cloth and carbon paper. Of these, metal materials, particularly aluminum, are preferred.

  Examples of the shape of the current collector include metal foil, metal cylinder, metal coil, metal plate, metal thin film, expanded metal, punch metal, and foam metal in the case of a metal material. A thin film, a carbon cylinder, etc. are mentioned. Of these, metal thin films are preferred. In addition, you may form a thin film suitably in mesh shape. Although the thickness of the thin film is arbitrary, it is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and the upper limit is usually 1 mm or less, preferably 100 μm or less, more preferably 50 μm or less. If the thin film is thinner than this range, the strength required for the current collector may be insufficient. Conversely, if the thin film is thicker than this range, the handleability may be impaired.

Moreover, it is also preferable from the viewpoint of reducing the electronic contact resistance between the current collector and the positive electrode active material layer that a conductive additive is applied to the surface of the current collector. Examples of the conductive assistant include noble metals such as carbon, gold, platinum, and silver.
The ratio of the thickness of the current collector to the positive electrode active material layer is not particularly limited, but the value of (thickness of the positive electrode active material layer on one side immediately before electrolyte injection) / (thickness of the current collector) is 20 The lower limit is preferably 15 or less, most preferably 10 or less, and the lower limit is preferably 0.5 or more, more preferably 0.8 or more, and most preferably 1 or more. Above this range, the current collector may generate heat due to Joule heat during high current density charge / discharge. Below this range, the volume ratio of the current collector to the positive electrode active material increases and the battery capacity may decrease.

(Electrode area)
When using the non-aqueous electrolyte of the present invention, it is preferable that the area of the positive electrode active material layer is larger than the outer surface area of the battery outer case from the viewpoint of increasing the stability at high output and high temperature. Specifically, the sum of the electrode areas of the positive electrode with respect to the surface area of the exterior of the secondary battery is preferably 15 times or more, and more preferably 40 times or more. The outer surface area of the outer case is the total area obtained by calculation from the vertical, horizontal, and thickness dimensions of the case part filled with the power generation element excluding the protruding part of the terminal in the case of a bottomed square shape. . In the case of a bottomed cylindrical shape, the geometric surface area approximates the case portion filled with the power generation element excluding the protruding portion of the terminal as a cylinder. The total electrode area of the positive electrode is the geometric surface area of the positive electrode mixture layer facing the mixture layer containing the negative electrode active material, and in the structure in which the positive electrode mixture layer is formed on both sides via the current collector foil. , The sum of the areas where each surface is calculated separately.

(Thickness of positive plate)
The thickness of the positive electrode plate is not particularly limited, but from the viewpoint of high capacity and high output, the thickness of the composite layer obtained by subtracting the metal foil thickness of the core material is preferably as a lower limit with respect to one side of the current collector. Is 10 μm or more, more preferably 20 μm or more, and the upper limit is preferably 500 μm or less, more preferably 450 μm or less.

(Positive electrode surface coating)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said positive electrode plate. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate, and carbon.

3. Negative electrode The negative electrode active material used for the negative electrode is described below. The negative electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions, and specific examples include carbonaceous materials, alloy-based materials, lithium-containing metal composite oxide materials, and the like. However, when a carbonaceous material is used, it is preferable to contain at least one negative electrode active material composed of graphite particles having a rhombohedral crystal ratio of 0% to 35%. These may be used individually by 1 type, and may be used together combining 2 or more types arbitrarily.

<Negative electrode active material>
Examples of the negative electrode active material include carbonaceous materials, alloy materials, lithium-containing metal composite oxide materials, and the like.
As a carbonaceous material used as a negative electrode active material,
(1) natural graphite,
(2) a carbonaceous material obtained by heat-treating an artificial carbonaceous material and an artificial graphite material at least once in the range of 400 to 3200 ° C;
(3) a carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two or more different crystallinities and / or has an interface in contact with the different crystalline carbonaceous materials,
(4) A carbonaceous material in which the negative electrode active material layer is made of carbonaceous materials having at least two or more different orientations and / or has an interface in contact with the carbonaceous materials having different orientations,
Is preferably a good balance between initial irreversible capacity and high current density charge / discharge characteristics. Moreover, the carbonaceous materials (1) to (4) may be used alone or in combination of two or more in any combination and ratio.

  Examples of the artificial carbonaceous material and artificial graphite material of (2) above include natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, those obtained by oxidizing these pitches, needle coke, pitch coke and Carbon materials that are partially graphitized, furnace black, acetylene black, organic pyrolysis products such as pitch-based carbon fibers, carbonizable organic materials and their carbides, or carbonizable organic materials are benzene, toluene, xylene, quinoline And a solution dissolved in a low-molecular organic solvent such as n-hexane, and carbides thereof.

  As an alloy material used as the negative electrode active material, as long as lithium can be occluded / released, lithium alone, simple metals and alloys forming lithium alloys, or oxides, carbides, nitrides, silicides, sulfides thereof Any of compounds such as products or phosphides may be used and is not particularly limited. The single metal and alloy forming the lithium alloy are preferably materials containing group 13 and group 14 metal / metalloid elements (that is, excluding carbon), more preferably aluminum, silicon and tin (hereinafter referred to as “ Simple metals) and alloys or compounds containing these atoms (sometimes abbreviated as “specific metal elements”).

  As a negative electrode active material having at least one kind of atom selected from a specific metal element, a metal simple substance of any one specific metal element, an alloy composed of two or more specific metal elements, one type or two or more specific types Alloys comprising metal elements and one or more other metal elements, as well as compounds containing one or more specific metal elements, and oxides, carbides, nitrides and silicides of the compounds And composite compounds such as sulfides or phosphides. By using these simple metals, alloys or metal compounds as the negative electrode active material, the capacity of the battery can be increased.

  In addition, a compound in which these complex compounds are complexly bonded to several kinds of elements such as a simple metal, an alloy, or a nonmetallic element is also included. Specifically, for example, in silicon and tin, an alloy of these elements and a metal that does not operate as a negative electrode can be used. For example, in the case of tin, a complex compound containing 5 to 6 kinds of elements in combination with a metal that acts as a negative electrode other than tin and silicon, a metal that does not operate as a negative electrode, and a nonmetallic element may be used. it can.

  Among these negative electrode active materials, since the capacity per unit mass is large when a battery is formed, any one simple metal of a specific metal element, an alloy of two or more specific metal elements, oxidation of a specific metal element In particular, silicon and / or tin metal simple substance, alloy, oxide, carbide, nitride and the like are preferable from the viewpoint of capacity per unit mass and environmental load.

  The lithium-containing metal composite oxide material used as the negative electrode active material is not particularly limited as long as it can occlude and release lithium, but a material containing titanium and lithium is preferable from the viewpoint of high current density charge / discharge characteristics, A lithium-containing composite metal oxide material containing titanium is more preferable, and a composite oxide of lithium and titanium (hereinafter sometimes abbreviated as “lithium titanium composite oxide”). That is, it is particularly preferable to use a lithium titanium composite oxide having a spinel structure in a negative electrode active material for a non-aqueous electrolyte battery because the output resistance is greatly reduced.

In addition, lithium or titanium of the lithium titanium composite oxide is at least selected from the group consisting of other metal elements such as Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. Those substituted with one element are also preferred.
The metal oxide is a lithium titanium composite oxide represented by the general formula (A). In the general formula (A), 0.7 ≦ x ≦ 1.5, 1.5 ≦ y ≦ 2.3, It is preferable that 0 ≦ z ≦ 1.6 because the structure upon doping and dedoping of lithium ions is stable.

Li _x Ti _y M _z O ₄ (A)
[In the general formula (A), M represents at least one element selected from the group consisting of Na, K, Co, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn, and Nb. ]
Among the compositions represented by the general formula (A),
(A) 1.2 ≦ x ≦ 1.4, 1.5 ≦ y ≦ 1.7, z = 0
(B) 0.9 ≦ x ≦ 1.1, 1.9 ≦ y ≦ 2.1, z = 0
(C) 0.7 ≦ x ≦ 0.9, 2.1 ≦ y ≦ 2.3, z = 0
This structure is particularly preferable because of a good balance of battery performance.

Particularly preferred representative compositions of the above compounds are Li _4/3 Ti _5/3 O ₄ in (a), Li ₁ Ti ₂ O ₄ in (b), and Li _4/5 Ti _11/5 O in (c). ₄ . As for the structure of Z ≠ 0, for example, Li _4/3 Ti _4/3 Al _1/3 O ₄ is preferable.

[Rhombohedral crystal ratio]
The rhombohedral crystal ratio defined in the present invention is expressed by the following formula based on the ratio of rhombohedral structure graphite layer (ABC stacking layer) and hexagonal structure graphite layer (AB stacking layer) by X-ray wide angle diffraction (XRD). Can be obtained.

Rhombohedral crystal ratio (%) = integrated intensity of ABC (101) peak of XRD ÷
XRD AB (101) peak integrated intensity × 100
Here, the rhombohedral crystal ratio of the graphite particles of the present invention is usually 0% or more, preferably more than 0%, more preferably 3% or more, still more preferably 5% or more, particularly preferably 12% or more, Usually, it is 35% or less, preferably 27% or less, more preferably 24% or less, and particularly preferably 20% or less. Here, the rhombohedral crystal ratio of 0% indicates that no XRD peak derived from the ABC stacking layer is detected. On the other hand, “greater than 0%” means that even a slight XRD peak derived from the ABC stacking layer is detected.

  If the rhombohedral crystal ratio is too large, many defects are contained in the crystal structure of the graphite particles, so that the amount of Li inserted tends to decrease and it is difficult to obtain a high capacity. In addition, since the electrolyte is decomposed during the cycle due to the defects, the cycle characteristics tend to deteriorate. On the other hand, if the rhombohedral crystal ratio is within the range of the present invention, for example, the crystal structure of the graphite particles has few defects and low reactivity with the electrolytic solution, and the consumption of the electrolytic solution during the cycle is small and the cycle characteristics. It is preferable because it is excellent.

The XRD measurement method for determining the rhombohedral crystal ratio is as follows.
A 0.2 mm sample plate is packed so that the graphite powder is not oriented, and measured with an X-ray diffractometer (for example, X'Pert Pro MPD manufactured by PANalytical, with CuKα ray, output 45 kV, 40 mA). Using the obtained diffraction pattern, the peak integrated intensity is calculated by profile fitting using the asymmetric Pearson VII function using analysis software JADE5.0, and the rhombohedral crystal ratio is obtained from the above formula.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Solar slit 0.04 degree divergence slit 0.5 degree side divergence mask 15mm
Anti-scattering slit 1 degree ・ Measurement range and step angle / measurement time:
(101) plane: 41 ° ≦ 2θ ≦ 47.5 ° 0.3 ° / 60 seconds. Background correction: A line between 42.7 and 45.5 ° is connected by a straight line and subtracted as background.
-Peak of rhombohedral-structure graphite particle layer: refers to a peak around 43.4 degrees.
-Peak of hexagonal structure graphite particle layer: It indicates a peak around 44.5 degrees.

  A method for obtaining graphite particles having a rhombohedral crystal ratio in the above range can employ a method of manufacturing using conventional techniques, and is not particularly limited, but the graphite particles are heat-treated at a temperature of 500 ° C. or higher. It is preferable to manufacture by this. It is also preferable to give the graphite particles mechanical action such as compression, friction, shearing force, etc. including the interaction of particles mainly with impact force. In addition, the rhombohedral crystal ratio can be adjusted by changing the strength of the mechanical action, the processing time, the presence or absence of repetition, and the like. As a specific device for adjusting the rhombohedral crystal ratio, there is a rotor with a large number of blades installed inside the casing, and the rotor rotates at a high speed, thereby impacting the carbon material introduced inside. An apparatus that applies a mechanical action such as compression, friction, shearing force, etc. and performs surface treatment is preferable. Moreover, it is preferable to have a mechanism that repeatedly gives a mechanical action by circulating a carbon material, or a mechanism that does not have a circulation mechanism but connects a plurality of apparatuses. As an example of a preferable apparatus, there can be mentioned a hybridization system manufactured by Nara Machinery Co., Ltd.

Further, it is more preferable to apply a heat treatment after applying the mechanical action.
Further, it is particularly preferable that after applying the mechanical action, it is combined with a carbon precursor and subjected to heat treatment at a temperature of 700 ° C. or higher.

[Specific Embodiment of Negative Electrode Active Material]
Specific embodiments of the negative electrode active material include, for example, (a) graphite particles having a rhombohedral crystal ratio of 0% to 35% composed of a composite and / or mixture of nuclear graphite and carbon, and (b) nuclear graphite and graphite. Graphite particles having a rhombohedral crystal ratio of 0% to 35%, (c) graphite particles having a rhombohedral crystal ratio of 0% to 35%, and (a) to (c) ) And the like.

Here, examples of the nuclear graphite include the aforementioned natural graphite and artificial graphite. The natural graphite as the core graphite is preferably spherical natural graphite (in this specification, spherical natural graphite is also referred to as spheroidized graphite).
For example, in the case of a mixture of (a) and (b), the ratio of the complex and / or mixture of (b) to the complex and / or mixture of (a) is usually 5 wt% or more, preferably Is 10 wt% or more, more preferably 15 wt% or more. Moreover, it is 95 wt% or less normally, Preferably it is 90 wt% or less, More preferably, it is 85 wt% or less. When the mixing ratio of (b) is too small, the irreversible capacity tends to increase and the battery capacity tends to decrease, and when the mixing ratio is too large, the Li acceptability at low temperatures tends to decrease.

  In the case of a mixture of (a) and (c), the ratio of the graphite particles of (c) to the composite and / or mixture of (a) is usually 5 wt% or more, preferably 10 wt% or more. Preferably it is 15 wt% or more. Moreover, it is 70 wt% or less normally, Preferably it is 60 wt% or less, More preferably, it is 50 wt% or less. If the mixing ratio of (c) is too small, there is a concern that when the electrode is pressed at a high density in order to increase the battery capacity, there is a concern that the press load becomes high and it is difficult to increase the density. May decrease.

  In the case of a mixture of (b) and (c), the ratio of the graphite particles of (c) to the composite and / or mixture of (b) is usually 5 wt% or more, preferably 10 wt% or more. Preferably it is 20 wt% or more. Moreover, it is 70 wt% or less normally, Preferably it is 60 wt% or less, More preferably, it is 50 wt% or less. If the mixing ratio of (c) is too small, the electrode load tends to be high when the electrodes are pressed at a high density in order to increase the battery capacity, and the density tends to be difficult to increase. There is a tendency to decrease.

  As a combination of these, the combination of the composite of (a) and the composite of (b), the combination of the composite of (a) and the graphite particles of (c), the composite of (b) and the graphite particles of (c) The combination of (a) and (b), and the combination of (a) and (c) graphite particles make it easy to produce a high-density electrode and secure a conductive path. It is more preferable because it is easily processed and has excellent cycle characteristics.

  The negative electrode according to the present invention may contain graphite particles whose rhombohedral crystal ratio does not satisfy the above range. When the graphite particles are mixed with other graphite having a rhombohedral crystal ratio outside the range of 0% or more and 35% or less, the other graphite is usually 2 wt% or more with respect to the graphite particle mass of the present invention. Preferably it is 5 wt% or more, More preferably, it is 10 wt% or more. Moreover, it is 50 wt% or less normally, Preferably it is 45 wt% or less, More preferably, it is 40 wt% or less. If the amount of other graphite is too small, the effect of mixing other graphite tends to be difficult to obtain, and if it is too large, the effect of the present invention tends to be small.

  When the negative electrode active material contains (a) and / or (b), the rhombohedral crystal ratio of the nuclear graphite constituting these composites is usually 0% or more, preferably 3% or more, like the graphite particles. More preferably, it is 5% or more, usually 35% or less, preferably 27% or less, more preferably 24% or less, and particularly preferably 20% or less. The rhombohedral crystal ratio of the nuclear graphite constituting these composites can be determined by the same method as that for the graphite particles.

(A) Graphite particles having a rhombohedral crystal ratio of 0% to 35% composed of a composite and / or mixture of nuclear graphite and carbon. A rhombohedral crystal ratio composed of a composite and / or a mixture of nuclear graphite and carbon is 0%. More than 35% of graphite particles are, for example, coating or bonding a carbon precursor to nuclear graphite and then firing at 600 ° C. to 2200 ° C., or vapor deposition by a CVD (Chemical Vapor Deposition) method. , Etc.

The composite refers to graphite particles in which carbon is coated or bonded to nuclear graphite and the rhombohedral crystal ratio is within the above range. The coverage of carbon is usually 1% by mass or more, preferably 2% by mass or more, and usually 15% by mass or less, preferably 10% by mass or less.
The coverage of the present invention can be calculated using the following formula from the mass of nuclear graphite and the mass of carbon derived from the carbon precursor after firing.

Coverage (mass%) = carbon mass ÷ (nuclear graphite mass + carbon mass) × 100
The mixture refers to, for example, a mixture of graphite particles having a rhombohedral crystal ratio of 0% or more and 35% or less and carbon in an arbitrary ratio without being covered or bonded.
(B) Graphite particles having a rhombohedral crystal ratio of 0% or more and 35% or less composed of a composite and / or mixture of nuclear graphite and graphite. A rhombohedral crystal ratio composed of a composite and / or mixture of nuclear graphite and graphite is 0%. The 35% or less graphite particles can be obtained, for example, by coating or bonding a carbon precursor to nuclear graphite and then graphitizing at a temperature of 2300 ° C. to 3200 ° C.

The composite refers to graphite particles in which easy graphite and / or hard graphite is coated or bonded to nuclear graphite and rhombohedral crystallinity is 0% or more and 35% or less.
The coverage of graphite is usually 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and usually 50% by mass or less, preferably 30% by mass or less.
The coverage referred to in the present invention can be calculated from the mass of nuclear graphite and the mass of graphite derived from the carbon precursor after graphitization using the following formula.

Coverage (mass%) = precursor-derived graphite mass ÷
(Nuclear graphite mass + precursor-derived graphite mass) × 100
The mixture refers to, for example, a mixture of graphite particles having a rhombohedral crystal ratio of 0% or more and 35% or less and graphite in an arbitrary ratio without being covered or bonded.
(C) Graphite particles having a rhombohedral crystal ratio of 0% or more and 35% or less The graphite particles having a rhombohedral crystal ratio of 0% or more and 35% or less do not include the structures (a) and (b). It refers to those consisting only of graphite particles having a rhombohedral crystal ratio of 0% or more and 35% or less. Specifically, it is nuclear graphite that has been subjected to mechanical energy treatment, and refers to graphite particles that are not compounded or mixed with carbon and / or graphite. Further, graphite particles obtained by firing graphite particles having a rhombohedral crystal ratio of 0% to 35% at 400 ° C. to 3200 ° C. can also be used.

The graphite particles may be composed of one kind, or may be composed of a plurality of graphite particles having different forms and particle sizes.
<Physical properties of carbonaceous materials>
When using a carbonaceous material as a negative electrode active material, it is desirable to have the following physical properties.

(X-ray parameters)
The d value (interlayer distance) of the lattice plane (002 plane) obtained by X-ray diffraction by the Gakushin method of carbonaceous material is preferably 0.335 nm or more, and is usually 0.360 nm or less, 0 350 nm or less is preferable, and 0.345 nm or less is more preferable. Further, the crystallite size (Lc) of the carbonaceous material obtained by X-ray diffraction by the Gakushin method is preferably 1.0 nm or more, and more preferably 1.5 nm or more.

(Volume-based average particle size)
The volume-based average particle diameter of the carbonaceous material is a volume-based average particle diameter (median diameter) obtained by a laser diffraction / scattering method, and is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and 7 μm. The above is particularly preferable, and is usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, further preferably 30 μm or less, and particularly preferably 25 μm or less.

If the volume-based average particle size is below the above range, the irreversible capacity may increase, leading to loss of initial battery capacity. On the other hand, when the above range is exceeded, when an electrode is produced by coating, an uneven coating surface tends to be formed, which may be undesirable in the battery production process.
The volume-based average particle size is measured by dispersing carbon powder in a 0.2% by weight aqueous solution (about 10 mL) of polyoxyethylene (20-mer) sorbitan monolaurate, which is a surfactant, and using a laser diffraction / scattering method. This is performed using a particle size distribution meter (LA-700, manufactured by Horiba, Ltd.). The median diameter determined by the measurement is defined as the volume-based average particle diameter of the carbonaceous material.

(Raman R value, Raman half width)
The Raman R value of the carbonaceous material is a value measured using an argon ion laser Raman spectrum method, and is usually 0.01 or more, preferably 0.03 or more, more preferably 0.1 or more, and usually 1.5 or less, preferably 1.2 or less, more preferably 1 or less, and particularly preferably 0.5 or less.

  When the Raman R value is below the above range, the crystallinity of the particle surface becomes too high, and there are cases where the number of sites where Li enters between layers decreases with charge / discharge. That is, charge acceptance may be reduced. In addition, when the negative electrode is densified by applying it to the current collector and then pressing it, the crystals are likely to be oriented in a direction parallel to the electrode plate, which may lead to a decrease in load characteristics. In particular, when the Raman R value is 0.1 or more, a suitable film can be formed on the surface of the negative electrode, whereby storage characteristics, cycle characteristics, and load characteristics can be improved.

On the other hand, if it exceeds the above range, the crystallinity of the particle surface is lowered, the reactivity with the non-aqueous electrolyte is increased, and the efficiency may be lowered and the gas generation may be increased.
Further, the Raman half-width in the vicinity of 1580 cm ^{−1 of the} carbonaceous material is not particularly limited, but is usually 10 cm ⁻¹ or more, preferably 15 cm ⁻¹ or more, and usually 100 cm ⁻¹ or less, and 80 cm ⁻¹ or less. Preferably, 60 cm ⁻¹ or less is more preferable, and 40 cm ⁻¹ or less is particularly preferable.

  If the Raman half width is less than the above range, the crystallinity of the particle surface becomes too high, and there are cases where the number of sites where Li enters between layers decreases with charge and discharge. That is, charge acceptance may be reduced. In addition, when the negative electrode is densified by applying it to the current collector and then pressing it, the crystals are likely to be oriented in a direction parallel to the electrode plate, which may lead to a decrease in load characteristics. On the other hand, if it exceeds the above range, the crystallinity of the particle surface is lowered, the reactivity with the non-aqueous electrolyte is increased, and the efficiency may be lowered and the gas generation may be increased.

The measurement of the Raman spectrum, using a Raman spectrometer (manufactured by JASCO Corporation Raman spectrometer), the sample is naturally dropped into the measurement cell and filled, and while irradiating the sample surface in the cell with argon ion laser light, This is done by rotating the cell in a plane perpendicular to the laser beam. The resulting Raman spectrum, the intensity _{I A} of the peak _{P A} in the vicinity of 1580 cm ^-1, and measuring the intensity _{I B} of a peak _{P B} in the vicinity of 1360 cm ^-1, the intensity ratio _{R (R = I B / I} A) Is calculated. The Raman R value calculated by the measurement is defined as the Raman R value of the carbonaceous material of the present invention. Further, the half width of the peak P _A in the vicinity of 1580 cm ^-1 of the resulting Raman spectrum was measured, which is defined as the Raman half-value width of the carbonaceous material.

Moreover, said Raman measurement conditions are as follows.
Argon ion laser wavelength: 514.5nm
・ Laser power on the sample: 15-25mW
・ Resolution: 10-20cm ^-1
Measurement range: 1100 cm ^{−1 to} 1730 cm ⁻¹
・ Raman R value, Raman half-width analysis: Background processing ・ Smoothing processing: Simple average, 5 points of convolution (BET specific surface area)

BET specific surface area of the carbonaceous material is a value of the measured specific surface area using the BET method is usually 0.1 m ² · ^{g -1} or more, 0.7 m ² · ^{g -1} or more, 1. 0 m ² · ^{g -1} or more, and particularly preferably 1.5 m ² · ^{g -1} or more, generally not more than 100 m ² · ^{g -1,} preferably ^{25 m} 2 · ^{g -1} or less, 15 m ² · g ^-1 more preferably less, ^{10 m} 2 · ^{g -1} or less are especially preferred.

When the value of the BET specific surface area is less than this range, the acceptability of lithium is likely to deteriorate during charging when used as a negative electrode material, lithium is likely to precipitate on the electrode surface, and stability may be reduced. On the other hand, if it exceeds this range, when used as a negative electrode material, the reactivity with the non-aqueous electrolyte increases, gas generation tends to increase, and a preferable battery may be difficult to obtain.

  The specific surface area was measured by the BET method using a surface area meter (a fully automated surface area measuring device manufactured by Okura Riken), preliminarily drying the sample at 350 ° C. for 15 minutes under nitrogen flow, Using a nitrogen helium mixed gas accurately adjusted so that the value of the relative pressure becomes 0.3, the nitrogen adsorption BET one-point method by the gas flow method is used. The specific surface area determined by the measurement is defined as the BET specific surface area of the carbonaceous material.

(Roundness)
When the circularity is measured as the degree of the sphere of the carbonaceous material, it is preferably within the following range. The circularity is defined as “circularity = (peripheral length of an equivalent circle having the same area as the particle projection shape) / (actual perimeter of the particle projection shape)”, and is theoretical when the circularity is 1. Become a true sphere.
The circularity of the particles having a particle size of 3 to 40 μm in the range of the carbonaceous material is desirably closer to 1, and is preferably 0.1 or more, more preferably 0.5 or more, and more preferably 0.8 or more, 0.85 or more is more preferable, and 0.9 or more is particularly preferable. High current density charge / discharge characteristics improve as the degree of circularity increases. Therefore, when the circularity is less than the above range, the filling property of the negative electrode active material is lowered, the resistance between particles is increased, and the high current density charge / discharge characteristics may be lowered for a short time.

  The circularity is measured using a flow type particle image analyzer (FPIA manufactured by Sysmex Corporation). About 0.2 g of a sample was dispersed in a 0.2% by mass aqueous solution (about 50 mL) of polyoxyethylene (20) sorbitan monolaurate as a surfactant, and irradiated with 28 kHz ultrasonic waves at an output of 60 W for 1 minute. The detection range is specified as 0.6 to 400 μm, and the particle size is measured in the range of 3 to 40 μm. The circularity determined by the measurement is defined as the circularity of the carbonaceous material.

  The method for improving the circularity is not particularly limited, but a sphere-shaped sphere is preferable because the shape of the interparticle void when the electrode body is formed is preferable. Examples of spheroidizing treatment include a method of mechanically approaching a sphere by applying a shearing force and a compressive force, a mechanical / physical processing method of granulating a plurality of fine particles by the binder or the adhesive force of the particles themselves, etc. Is mentioned.

(Tap density)
The tap density of the carbonaceous material is usually 0.1 g · cm ⁻³ or more, preferably 0.5 g · cm ⁻³ or more, more preferably 0.7 g · cm ⁻³ or more, and 1 g · cm ⁻³ or more. Particularly preferable, 2 g · cm ⁻³ or less is preferable, 1.8 g · cm ⁻³ or less is more preferable, and 1.6 g · cm ⁻³ or less is particularly preferable. When the tap density is below the above range, the packing density is difficult to increase when used as a negative electrode, and a high-capacity battery may not be obtained. On the other hand, when the above range is exceeded, there are too few voids between particles in the electrode, it is difficult to ensure conductivity between the particles, and it may be difficult to obtain preferable battery characteristics.

The tap density is measured by passing through a sieve having an opening of 300 μm, dropping the sample onto a 20 cm ³ tapping cell and filling the sample to the upper end surface of the cell, and then measuring a powder density measuring device (for example, manufactured by Seishin Enterprise Co., Ltd.). Using a tap denser, tapping with a stroke length of 10 mm is performed 1000 times, and the tap density is calculated from the volume at that time and the mass of the sample. The tap density calculated by the measurement is defined as the tap density of the carbonaceous material.

(Orientation ratio)
The orientation ratio of the carbonaceous material is usually 0.005 or more, preferably 0.01 or more,
It is more preferably 15 or more, and usually 0.67 or less. When the orientation ratio is below the above range, the high-density charge / discharge characteristics may deteriorate. The upper limit of the above range is the theoretical upper limit value of the orientation ratio of the carbonaceous material.

The orientation ratio is measured by X-ray diffraction after pressure-molding the sample. Set the molding obtained by filling 0.47 g of the sample into a molding machine with a diameter of 17 mm and compressing it with 58.8 MN · m ^{-2 so} that it is flush with the surface of the sample holder for measurement. X-ray diffraction is measured. From the (110) diffraction and (004) diffraction peak intensities of the obtained carbon, a ratio represented by (110) diffraction peak intensity / (004) diffraction peak intensity is calculated. The orientation ratio calculated by the measurement is defined as the orientation ratio of the carbonaceous material.

The X-ray diffraction measurement conditions are as follows. “2θ” indicates a diffraction angle.
・ Target: Cu (Kα ray) graphite monochromator ・ Slit:
Divergence slit = 0.5 degree Light receiving slit = 0.15 mm
Scattering slit = 0.5 degree / measurement range and step angle / measurement time:
(110) face: 75 degrees ≦ 2θ ≦ 80 degrees 1 degree / 60 seconds (004) face: 52 degrees ≦ 2θ ≦ 57 degrees 1 degree / 60 seconds (aspect ratio (powder))

  The aspect ratio of the carbonaceous material is usually 1 or more and usually 10 or less, preferably 8 or less, and more preferably 5 or less. If the aspect ratio exceeds the above range, streaking or a uniform coated surface cannot be obtained when forming an electrode plate, and the high current density charge / discharge characteristics may deteriorate. The lower limit of the above range is the theoretical lower limit value of the aspect ratio of the carbonaceous material.

  The aspect ratio is measured by magnifying and observing the carbonaceous material particles with a scanning electron microscope. Carbonaceous material particles when three-dimensional observation is performed by selecting arbitrary 50 graphite particles fixed to the end face of a metal having a thickness of 50 μm or less and rotating and tilting the stage on which the sample is fixed. The longest diameter A and the shortest diameter B orthogonal thereto are measured, and the average value of A / B is obtained. The aspect ratio (A / B) obtained by the measurement is defined as the aspect ratio of the carbonaceous material.

<Configuration and production method of negative electrode>
Any known method can be used for producing the electrode as long as the effects of the present invention are not significantly impaired. For example, it is formed by adding a binder, a solvent, and, if necessary, a thickener, a conductive material, a filler, etc. to a negative electrode active material to form a slurry, which is applied to a current collector, dried and then pressed. Can do.

(Current collector)
As the current collector for holding the negative electrode active material, a known material can be arbitrarily used. Examples of the current collector for the negative electrode include metal materials such as aluminum, copper, nickel, stainless steel, and nickel-plated steel. Copper is particularly preferable from the viewpoint of ease of processing and cost.
In addition, the shape of the current collector may be, for example, a metal foil, a metal cylinder, a metal coil, a metal plate, a metal thin film, an expanded metal, a punch metal, a foam metal, or the like when the current collector is a metal material. Among them, a metal thin film is preferable, a copper foil is more preferable, and a rolled copper foil by a rolling method and an electrolytic copper foil by an electrolytic method are more preferable, and both can be used as a current collector.
The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and is usually 100 μm or less, preferably 50 μm or less. This is because if the thickness of the negative electrode current collector is too thick, the capacity of the entire battery may be too low, and conversely if it is too thin, handling may be difficult.

(Thickness ratio between current collector and negative electrode active material layer)
The ratio of the thickness of the current collector to the negative electrode active material layer is not particularly limited, but the value of “(the thickness of the negative electrode active material layer on one side immediately before the nonaqueous electrolyte injection) / (thickness of the current collector)” However, 150 or less is preferable, 20 or less is more preferable, 10 or less is particularly preferable, 0.1 or more is preferable, 0.4 or more is more preferable, and 1 or more is particularly preferable. When the ratio of the thickness of the current collector to the negative electrode active material layer exceeds the above range, the current collector may generate heat due to Joule heat during high current density charge / discharge. On the other hand, below the above range, the volume ratio of the current collector to the negative electrode active material increases, and the battery capacity may decrease.

(Binder)
The binder for binding the negative electrode active material is not particularly limited as long as it is a material that is stable with respect to the non-aqueous electrolyte solution and the solvent used in manufacturing the electrode.
Specific examples include resin-based polymers such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, polyimide, cellulose, and nitrocellulose; SBR (styrene-butadiene rubber), isoprene rubber, butadiene rubber, fluorine rubber, Rubber polymers such as NBR (acrylonitrile / butadiene rubber) and ethylene / propylene rubber; styrene / butadiene / styrene block copolymer or hydrogenated product thereof; EPDM (ethylene / propylene / diene terpolymer), styrene / Thermoplastic elastomeric polymers such as ethylene / butadiene / styrene copolymers, styrene / isoprene / styrene block copolymers or hydrogenated products thereof; syndiotactic-1,2-polybutadiene, polyvinyl acetate , Soft resinous polymers such as ethylene / vinyl acetate copolymer, propylene / α-olefin copolymer; polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, polytetrafluoroethylene / ethylene copolymer, etc. And a polymer composition having ion conductivity of alkali metal ions (particularly lithium ions). These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  The ratio of the binder to the negative electrode active material is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, particularly preferably 0.6% by mass or more, and preferably 20% by mass or less, 15% by mass. The following is more preferable, 10% by mass or less is further preferable, and 8% by mass or less is particularly preferable. When the ratio of the binder with respect to a negative electrode active material exceeds the said range, the binder ratio from which the amount of binders does not contribute to battery capacity may increase, and the fall of battery capacity may be caused. On the other hand, below the above range, the strength of the negative electrode may be reduced.

  In particular, when a rubbery polymer typified by SBR is contained as a main component, the ratio of the binder to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, and 0 .6% by mass or more is more preferable, and is usually 5% by mass or less, preferably 3% by mass or less, and more preferably 2% by mass or less. When the main component contains a fluorine-based polymer typified by polyvinylidene fluoride, the ratio to the negative electrode active material is usually 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more. It is preferably 15% by mass or less, preferably 10% by mass or less, and more preferably 8% by mass or less.

(Slurry forming solvent)
The solvent for forming the slurry is not particularly limited as long as it is a solvent capable of dissolving or dispersing the negative electrode active material, the binder, and the thickener and conductive material used as necessary. Alternatively, either an aqueous solvent or an organic solvent may be used.
Examples of the aqueous solvent include water and alcohol. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N- Examples include dimethylaminopropylamine, tetrahydrofuran (THF), toluene, acetone, diethyl ether, dimethylacetamide, hexamethylphosphalamide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane, and the like.
In particular, when an aqueous solvent is used, it is preferable to add a dispersant or the like in addition to the thickener and make a slurry using a latex such as SBR. In addition, these solvents may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and a ratio.

(Thickener)
A thickener is usually used to adjust the viscosity of the slurry. The thickener is not particularly limited, and specific examples include carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and salts thereof. These may be used individually by 1 type, or may use 2 or more types together by arbitrary combinations and ratios.

  Further, when using a thickener, the ratio of the thickener to the negative electrode active material is usually 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.6% by mass or more, Moreover, it is 5 mass% or less normally, 3 mass% or less is preferable, and 2 mass% or less is more preferable. When the ratio of the thickener to the negative electrode active material is less than the above range, applicability may be significantly reduced. Moreover, when it exceeds the said range, the ratio of the negative electrode active material which occupies for a negative electrode active material layer will fall, and the problem that the capacity | capacitance of a battery falls and the resistance between negative electrode active materials may increase.

(Electrode density)
The electrode structure when the negative electrode active material is made into an electrode is not particularly limited, but the density of the negative electrode active material present on the current collector is preferably 1 g · cm ⁻³ or more, and 1.2 g · cm ⁻³ or more. but more preferably, particularly preferably 1.3 g · ^{cm -3} or more, preferably 2.2 g · ^{cm -3} or less, more preferably 2.1 g · ^{cm -3} or less, 2.0 g · ^{cm -3} or less Further preferred is 1.9 g · cm ⁻³ or less. When the density of the negative electrode active material existing on the current collector exceeds the above range, the negative electrode active material particles are destroyed, and the initial irreversible capacity increases or non-aqueous system near the current collector / negative electrode active material interface. There is a case where high current density charge / discharge characteristics are deteriorated due to a decrease in permeability of the electrolytic solution. On the other hand, if the amount is less than the above range, the conductivity between the negative electrode active materials decreases, the battery resistance increases, and the capacity per unit volume may decrease.

(Thickness of negative electrode plate)
The thickness of the negative electrode plate is designed according to the positive electrode plate to be used, and is not particularly limited. However, the thickness of the composite layer obtained by subtracting the thickness of the metal foil of the core is usually 15 μm or more, preferably 20 μm or more. More preferably, it is 30 μm or more, and usually 300 μm or less, preferably 280 μm or less, more preferably 250 μm or less.

(Surface coating of negative electrode plate)
Moreover, you may use what adhered the substance of the composition different from this to the surface of the said negative electrode plate. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate And sulfates such as aluminum sulfate and carbonates such as lithium carbonate, calcium carbonate and magnesium carbonate.

4). Separator In the non-aqueous electrolyte secondary battery of the present invention, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the nonaqueous electrolytic solution of the present invention is usually used by impregnating the separator.
The material and shape of the separator are not particularly limited, and known ones can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired. Among these, in the present invention, polyolefin resins, other resins, glass fibers, inorganic substances, etc., which are formed of a material that is stable with respect to the non-aqueous electrolyte solution of the present invention can be used as constituent components. As the shape, it is preferable to use a porous sheet excellent in liquid retention or a non-woven fabric.

The separator used in the present invention preferably has a polyolefin-based resin as a component. Specific examples of the polyolefin resin include polyethylene resin, polypropylene resin, 1-polymethylpentene, and polyphenylene sulfide.
Examples of polyethylene resins include low-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, medium-density polyethylene, high-density polyethylene, and copolymers based on ethylene, that is, ethylene and propylene, butene -1, pentene-1, hexene-1, heptene-1, octene-1, etc., α-olefins having 3 to 10 carbon atoms; vinyl esters such as vinyl acetate and vinyl propionate; methyl acrylate, ethyl acrylate, methacryl A copolymer or multi-component copolymer with one or two or more comonomers selected from unsaturated carboxylic acid esters such as methyl acrylate and ethyl methacrylate, and unsaturated compounds such as conjugated and non-conjugated dienes, or The mixed composition is mentioned. The ethylene unit content of the ethylene polymer is usually more than 50% by mass.

Among these polyethylene resins, at least one polyethylene resin selected from low density polyethylene, linear low density polyethylene, and high density polyethylene is preferable, and high density polyethylene is most preferable.
Moreover, there is no restriction | limiting in particular in the polymerization catalyst of a polyethylene-type resin, Any things, such as a Ziegler type catalyst, a Phillips type catalyst, and a Kaminsky type catalyst, may be sufficient. As a polymerization method of the polyethylene resin, there are a one-stage polymerization, a two-stage polymerization, or a multistage polymerization more than that, and any method of the polyethylene resin can be used.

The melt flow rate (MFR) of the polyethylene resin is not particularly limited, but usually the MFR is preferably 0.03 to 15 g / 10 min, and preferably 0.3 to 10 g / 10 min. preferable. If the MFR is in the above range, the back pressure of the extruder does not become too high during the molding process and the productivity is excellent. The MFR in the present invention is JIS K7210.
The measured value under the conditions of a temperature of 190 ° C. and a load of 2.16 kg.

The production method of the polyethylene resin is not particularly limited, and is a known polymerization method using a known olefin polymerization catalyst, for example, a multisite catalyst represented by a Ziegler-Natta type catalyst or a metallocene catalyst. A polymerization method using a single site catalyst may be mentioned.
Next, an example of a polypropylene resin will be described. The polypropylene resin in the present invention is homopolypropylene (propylene homopolymer), or propylene and ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene or 1-decene. And a random copolymer or block copolymer with α-olefin. Among these, when used for a battery separator, homopolypropylene is more preferably used from the viewpoint of mechanical strength.

The polypropylene resin preferably has an isotactic pentad fraction exhibiting stereoregularity of 80 to 99%, more preferably 83 to 98%, and still more preferably 85 to 97%. use. If the isotactic pentad fraction is too low, the mechanical strength of the battery separator may decrease. On the other hand, the upper limit of the isotactic pentad fraction is defined by the upper limit that can be obtained industrially at present, but this is not the case when a more regular resin is developed in the industrial level in the future. is not.

  The isotactic pentad fraction is a three-dimensional structure in which five methyl groups that are side chains are located in the same direction with respect to the main chain of carbon-carbon bonds composed of arbitrary five consecutive propylene units. Or the ratio is meant. Signal assignment of the methyl group region is as follows. Zambellietatal. (Macromol. 8, 687 (1975)).

  Moreover, it is preferable that Mw / Mn which is a parameter which shows molecular weight distribution of a polypropylene resin is 1.5-10.0. More preferably, 2.0 to 8.0, and still more preferably 2.0 to 6.0 is used. This means that the smaller the Mw / Mn, the narrower the molecular weight distribution. However, if the Mw / Mn is less than 1.5, problems such as a decrease in extrusion moldability occur, and it is difficult to produce industrially. There are many cases. On the other hand, when Mw / Mn exceeds 10.0, the low molecular weight component increases, and the mechanical strength of the obtained battery separator tends to decrease. Mw / Mn is obtained by GPC (gel per emission chromatography) method.

  Further, the melt flow rate (MFR) of the polypropylene resin is not particularly limited, but usually the MFR is preferably 0.1 to 15 g / 10 minutes, and preferably 0.5 to 10 g / 10 minutes. It is more preferable. When the MFR is less than 0.1 g / 10 minutes, the melt viscosity of the resin during the molding process is high, and the productivity is lowered. On the other hand, when it exceeds 15 g / 10 minutes, practical problems such as insufficient strength of the obtained battery separator tend to occur. MFR is measured under the conditions of a temperature of 230 ° C. and a load of 2.16 kg in accordance with JIS K7210.

As materials for other resins and glass fiber separators, for example, aromatic polyamide, polytetrafluoroethylene, polyethersulfone, glass filter, and the like can be used in combination with the polyolefin resin. These materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.
The thickness of the separator is arbitrary, but is usually 1 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less. If the separator is too thin than the above range, the insulating properties and mechanical strength may decrease. On the other hand, if it is thicker than the above range, not only the battery performance such as the rate characteristic may be lowered, but also the energy density of the whole non-aqueous electrolyte secondary battery may be lowered.

  Furthermore, when using a porous material such as a porous sheet or nonwoven fabric as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Further, it is usually 90% or less, preferably 85% or less, and more preferably 75% or less. If the porosity is too smaller than the above range, the membrane resistance tends to increase and the rate characteristics tend to deteriorate. Moreover, when larger than the said range, it exists in the tendency for the mechanical strength of a separator to fall and for insulation to fall.

Moreover, although the average pore diameter of a separator is also arbitrary, it is 0.5 micrometer or less normally, 0.2 micrometer or less is preferable, and it is 0.05 micrometer or more normally. If the average pore diameter exceeds the above range, a short circuit tends to occur. On the other hand, below the above range, the film resistance may increase and the rate characteristics may deteriorate.
On the other hand, as inorganic materials, for example, oxides such as alumina and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates such as barium sulfate and calcium sulfate are used. Used.

  As the form, a thin film shape such as a non-woven fabric, a woven fabric, or a microporous film is used. In the thin film shape, those having a pore diameter of 0.01 to 1 μm and a thickness of 5 to 50 μm are preferably used. In addition to the above-mentioned independent thin film shape, a separator formed by forming a composite porous layer containing the inorganic particles on the surface layer of the positive electrode and / or the negative electrode using a resin binder can be used. For example, a porous layer may be formed by using alumina particles having a 90% particle size of less than 1 μm on both surfaces of the positive electrode and using a fluororesin as a binder.

5. Battery design <Electrode group>
The electrode group has a laminated structure in which the positive electrode plate and the negative electrode plate are interposed through the separator, and a structure in which the positive electrode plate and the negative electrode plate are wound in a spiral shape through the separator. Either is acceptable. The ratio of the volume of the electrode group to the internal volume of the battery (hereinafter referred to as the electrode group occupation ratio) is usually 40% or more, preferably 50% or more, and usually 90% or less, preferably 80% or less. .

  When the electrode group occupancy is below the above range, the battery capacity decreases. Also, if the above range is exceeded, the void space is small, the battery expands, and the member expands or the vapor pressure of the electrolyte liquid component increases and the internal pressure rises. In some cases, the gas release valve that lowers various characteristics such as storage at high temperature and the like, or releases the internal pressure to the outside is activated.

<Current collection structure>
The current collecting structure is not particularly limited, but in order to more effectively realize the high current density charge / discharge characteristics by the non-aqueous electrolyte solution of the present invention, a structure that reduces the resistance of the wiring part and the joint part is used. It is preferable. Thus, when internal resistance is reduced, the effect of using the non-aqueous electrolyte solution of this invention is exhibited especially favorable.

  In the case where the electrode group has the above laminated structure, a structure formed by bundling the metal core portions of the electrode layers and welding them to the terminals is preferably used. When the area of one electrode increases, the internal resistance increases. Therefore, it is also preferable to provide a plurality of terminals in the electrode to reduce the resistance. When the electrode group has the winding structure described above, the internal resistance can be lowered by providing a plurality of lead structures for the positive electrode and the negative electrode, respectively, and bundling the terminals.

<Exterior case>
The material of the outer case is not particularly limited as long as it is a substance that is stable with respect to the non-aqueous electrolyte used. Specifically, a nickel-plated steel plate, stainless steel, aluminum, an aluminum alloy, a metal such as a magnesium alloy, or a laminated film (laminate film) of a resin and an aluminum foil is used. From the viewpoint of weight reduction, an aluminum or aluminum alloy metal or a laminate film is preferably used.

  In an exterior case using metals, the metal is welded together by laser welding, resistance welding, or ultrasonic welding to form a sealed sealed structure, or a caulking structure using the above metals via a resin gasket. Things. Examples of the outer case using the laminate film include a case where a resin-sealed structure is formed by heat-sealing resin layers. In order to improve sealing performance, a resin different from the resin used for the laminate film may be interposed between the resin layers. In particular, when a resin layer is heat-sealed through a current collecting terminal to form a sealed structure, a metal and a resin are joined, so that a resin having a polar group or a modified group having a polar group introduced as an intervening resin Resins are preferably used.

<Protective element>
As a protection element, PTC (Positive Temperature Coefficient) whose resistance increases when abnormal heat generation or excessive current flows, thermal fuse, thermistor, shuts off the current flowing through the circuit due to sudden increase in battery internal pressure or internal temperature in case of abnormal occurrence Valves (current cutoff valves, etc. can be used. It is preferable to select a protective element that does not operate under high current normal use, and it will not cause abnormal heat generation or thermal runaway without a protective element. It is better to be.

<Exterior body>
The non-aqueous electrolyte secondary battery of the present invention is usually configured by housing the non-aqueous electrolyte, the negative electrode, the positive electrode, the separator, and the like in an exterior body. This exterior body is not particularly limited, and any known one can be arbitrarily adopted as long as the effects of the present invention are not significantly impaired. Specifically, the material of the exterior body is arbitrary, but usually, for example, nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, or the like is used.
The shape of the exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

6). Battery Performance The non-aqueous electrolyte secondary battery of the present invention can be used without particular limitation, but can be preferably used for a battery having a high voltage or a high capacity.
For example, in the case of a lithium ion secondary battery, the increase in voltage is usually 4.35 V or higher, preferably 4.45 V or higher, more preferably 4.55 V or higher, more preferably 4.5 V or higher, based on Li / Li +. 65V or higher.
The increase in capacity is usually 2600 mAh or more, preferably 2800 mAh or more, more preferably 3000 mAh or more in the case of an 18650 type battery, for example.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.
[Manufacture of electrolyte]
Under a dry argon atmosphere, 4-fluoroethylene carbonate (MFEC) as the fluorinated cyclic carbonate represented by the general formula (1), and (2,2,2-) as the fluorinated chain carbonate represented by the general formula (2) Trifluoroethyl) methyl carbonate (TFEMC), ethylene carbonate (EC) as the non-fluorinated chain carbonate represented by the general formula (3), 1,3,5-tris (6-isocyanatohexyl)- 1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione (CTI) was mixed in the proportions listed in Table 1. Here, dried LiPF ₆ was dissolved at a rate of 1 mol / L to prepare basic electrolytic solutions 1, 2 and 3.

[Discharge capacity confirmation: Dependence of discharge current capacity on upper limit operating potential]
[Production of negative electrode]
98 parts by mass of natural graphite-based carbonaceous material (rhombohedral crystal ratio 30%), 100 parts by mass of aqueous dispersion of carboxymethylcellulose sodium (concentration of 1% by mass of carboxymethylcellulose sodium) and styrene as a thickener and binder, respectively -1 part by mass of an aqueous dispersion of butadiene rubber (concentration of styrene-butadiene rubber: 50% by mass) was added and mixed with a disperser to form a slurry. The obtained slurry was applied to a copper foil having a thickness of 10 μm, dried, and rolled with a press. The active material layer was 30 mm wide, 40 mm long, 5 mm wide, and 9 mm long uncoated. It cut out into the shape which has a part, and was set as the negative electrode used for discharge capacity confirmation.

[Production of positive electrode]
85% by mass of LiNi _0.5 Mn _1.5 O ₄ as a positive electrode active material, 10% by mass of acetylene black as a conductive material, and 5% by mass of polyvinylidene fluoride (PVdF) as a binder, Mix in a methylpyrrolidone solvent to make a slurry. The obtained slurry was applied to an aluminum foil having a thickness of 15 μm, dried, and rolled with a press. The active material layer was 30 mm in width, 40 mm in length, 5 mm in width, and 9 mm in length. It cut out into the shape which has a process part, and it was set as the positive electrode used for discharge capacity confirmation.

[Manufacture of lithium secondary batteries]
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, and the positive electrode to prepare a battery element. The battery element was inserted into a bag made of a laminate film in which both surfaces of aluminum (thickness: 40 μm) were coated with a resin layer while projecting positive and negative terminals, and then the basic electrolyte 1 shown in Table 1 was put into the bag. The battery was injected into the container and vacuum sealed to produce a sheet-like battery, which was used for confirming the discharge capacity.

[Run-in operation]
In a state where the produced sheet-like lithium secondary battery is sandwiched between glass plates in order to enhance the adhesion between the electrodes, the positive electrode potential is 4.95 V, 4.90 V at a constant current corresponding to 0.1 C at 25 ° C., The break-in operation was performed in the range of 4.85V, 4.75V, 4.65V, that is, the open circuit voltage between the battery terminals was 4.90V, 4.85V, 4.80V, 4.70V, 4.60V. Here, 1C represents a current value that discharges the reference capacity of the battery in one hour, 2C represents a current value that is twice that, and 0.1C represents a current value that is 1/10 of the current value. The battery was charged at a constant current of 1/3 C and discharged at a constant current of 1/3 C for 4 cycles in the range of 25 ° C., 3.0-open circuit voltage between the battery terminals. . The above process was used as a break-in operation for confirming the discharge capacity. Table 2 shows the discharge current capacity of each sheet-like lithium secondary battery after the break-in operation when discharging at 25 ° C. and 1/3 C constant current.

When the upper limit operating potential is in the range of 4.75-4.95V, it can be said that there is no significant difference in discharge capacity. On the other hand, the discharge capacity at 4.65 V is almost halved. This is because if the upper limit operating potential is too low, the battery cannot be charged to a sufficient depth and the capacity cannot be obtained. Therefore, in order to obtain a sufficient discharge capacity, it is preferable to charge so that the upper limit operating potential is 4.75 V or more. Therefore, the following durability evaluation was performed in a range where the upper limit operating potential at which a large discharge capacity can be taken out is 4.75V or more.

[Example 1]
[Production of negative electrode]
98 parts by mass of natural graphite-based carbonaceous material (rhombohedral crystal ratio 30%), 100 parts by mass of aqueous dispersion of carboxymethylcellulose sodium (concentration of 1% by mass of carboxymethylcellulose sodium) and styrene as a thickener and binder, respectively -1 part by mass of an aqueous dispersion of butadiene rubber (concentration of styrene-butadiene rubber: 50% by mass) was added and mixed with a disperser to form a slurry. The obtained slurry was applied to a copper foil having a thickness of 10 μm, dried, and rolled with a press. The active material layer was 30 mm wide, 40 mm long, 5 mm wide, and 9 mm long uncoated. It cut out into the shape which has a part, and was set as the negative electrode used for Example 1, respectively.

[Production of positive electrode]
85% by mass of LiNi _0.5 Mn _1.5 O ₄ as a positive electrode active material, 10% by mass of acetylene black as a conductive material, and 5% by mass of polyvinylidene fluoride (PVdF) as a binder, Mix in a methylpyrrolidone solvent to make a slurry. The obtained slurry was applied to an aluminum foil having a thickness of 15 μm, dried, and rolled with a press. The active material layer was 30 mm in width, 40 mm in length, 5 mm in width, and 9 mm in length. It cut out into the shape which has a process part, and it was set as the positive electrode used for Example 1, respectively.

[Manufacture of lithium secondary batteries]
The positive electrode, the negative electrode, and the polyethylene separator were laminated in the order of the negative electrode, the separator, and the positive electrode to prepare a battery element. The battery element was inserted into a bag made of a laminate film in which both surfaces of aluminum (thickness: 40 μm) were coated with a resin layer while projecting positive and negative terminals, and then the basic electrolyte 1 shown in Table 1 was put into the bag. It was injected into the interior, vacuum sealed, and a sheet-like battery was produced.

[Run-in operation]
The positive electrode potential is 4.75 V at a constant current corresponding to 0.1 C at 25 ° C., that is, between battery terminals, in a state where the produced sheet-like lithium secondary battery is sandwiched between glass plates in order to enhance the adhesion between the electrodes. The running-in operation was performed in the open circuit voltage range of 4.70V. Here, 1C represents a current value that discharges the reference capacity of the battery in one hour, 2C represents a current value that is twice that, and 0.1C represents a current value that is 1/10 of the current value. A process in which the battery is charged at a constant current of 1/3 C and discharged at a constant current of 1/3 C in the range of 25 ° C. and 3.0-4.70 V as an open circuit voltage between battery terminals is defined as 4 cycles. Cycled. The break-in operation of Example 1 was performed through the above steps. The evaluation results are shown in Table 3.

[Evaluation of cycle characteristics]
The battery that has completed the break-in operation is charged and discharged at a constant current of 1/3 C in a range of 3.0 to 4.70 V as an open circuit voltage between battery terminals at 60 ° C., and then charged and discharged at a constant current of 2 C. The process was performed as 200 cycles for 200 cycles. During this period, charge and discharge were performed at a constant current of 1/3 C at the 50th, 100th and 200th cycles, and the capacity was confirmed. The discharge capacity retention rate (cycle retention rate) was calculated from the formula of (discharge capacity at the 200th cycle) / (discharge capacity at the first cycle) × 100 in charge / discharge at a constant current of 1/3 C. Example 1 It was set as the evaluation result. The evaluation results are shown in Table 3.

[Example 2]
Regarding the running-in operation and the evaluation of the cycle characteristics, the positive electrode upper limit potential was 4.85 V, that is, the battery circuit open circuit voltage was 4.80 V, and the manufacture, the running-in operation, and the cycle characteristics were evaluated in the same manner as in Example 1. . The evaluation results are shown in Table 3.
[Example 3]
Regarding the running-in operation and the evaluation of cycle characteristics, manufacturing, running-in operation, and evaluation of cycle characteristics were performed in the same manner as in Example 1 except that the positive electrode upper limit potential was 4.90 V, that is, the open circuit voltage between battery terminals was 4.85 V. . The evaluation results are shown in Table 3.

[Example 4]
Regarding the production of the lithium secondary battery, the production, break-in operation, and cycle characteristics were evaluated in the same manner as in Example 2 except that the electrolytic solution 2 shown in Table 1 was used as the basic electrolytic solution. The evaluation results are shown in Table 3.
[Example 5]
Regarding the production of the lithium secondary battery, the production, the running-in operation, and the cycle characteristics were evaluated in the same manner as in Example 3 except that the electrolytic solution 2 shown in Table 1 was used as the basic electrolytic solution. The evaluation results are shown in Table 3.

[Comparative Example 1]
Regarding the production of a lithium secondary battery, the electrolytic solution 3 shown in Table 1 was used as a basic electrolytic solution, and the acclimatization operation and the evaluation of the cycle characteristics were performed. The positive electrode upper limit potential was 4.75 V, that is, the open circuit voltage between battery terminals was 4. Manufacture, running-in, and cycle characteristics were evaluated in the same manner as in Example 1 except that the voltage was 70V. The evaluation results are shown in Table 3.

[Comparative Example 2]
Regarding the running-in operation and the evaluation of cycle characteristics, manufacturing, running-in operation, and evaluation of cycle characteristics were performed in the same manner as in Example 1 except that the positive electrode upper limit potential was 4.95 V, that is, the open circuit voltage between the battery terminals was 4.90 V. . The evaluation results are shown in Table 3.
[Comparative Example 3]
Regarding the production of the lithium secondary battery, the production, break-in operation, and cycle characteristics were evaluated in the same manner as in Comparative Example 2, except that the electrolytic solution 2 shown in Table 1 was used as the basic electrolytic solution. The evaluation results are shown in Table 3.

Here, it can be seen that the high voltage design cells (Example 1, Example 2, Example 3) with the positive electrode upper limit potential set to 4.75V, 4.85V, 4.90V show a high cycle maintenance ratio.
In particular, in Example 1 in which the electrolytic solution of the present invention was used and the positive electrode upper limit potential was 4.75 V, the capacity retention rate after 200 cycles was as high as 82.0%, and in the high voltage design cell by applying this design It can be said that high durability can be realized. On the other hand, in a cycle test at the same positive electrode upper limit potential, when a non-aqueous electrolyte solution containing no fluorinated solvent according to the present invention was used, the capacity retention rate was greatly reduced to 55.7% (Comparative Example 1). . Thus, the fluorinated solvent according to the present invention is indispensable in order to obtain high durability in a high voltage design cell having an open circuit voltage between battery terminals exceeding 4.7V.

  Even when the upper limit operating potential is 4.95 V, the capacity retention rate after 200 cycles can be maintained up to about 55% by using the electrolytic solution of the present invention. However, this level is the same as the cycle maintenance ratio when the upper limit operating potential is 4.75 V and the electrolytic solution of the present invention is not used. On the other hand, when the electrolytic solution of the present invention is used in the region where the upper limit operating potential is 4.75-4.90 V, a high cycle capacity maintenance rate exceeding 60% is exhibited. When the upper limit operating potential is 4.65 V, considering that a sufficient capacity cannot be obtained at the stage after the initial break-in operation (Table 2), an appropriate combination of the developed electrolyte and the upper limit operating potential is high. It can be said that it is necessary in the voltage design cell.

That is, by using the electrolytic solution according to the present invention and setting the upper limit potential to 4.75 to 4.90 V, a high voltage battery having excellent durability can be obtained.
Further, when CTI was added as an auxiliary agent, an even better cycle maintenance rate was shown (Examples 4 and 5, Comparative Example 3). Although this effect is not specifically limited, it was guessed that it originated in the protective effect of the electrode surface by CTI.

  The non-aqueous electrolyte solution of the present invention is extremely useful because the durability characteristics of a non-aqueous electrolyte secondary battery with a high voltage design specification can be improved to a high degree. Therefore, the non-aqueous electrolyte solution of the present invention and the non-aqueous electrolyte secondary battery using the same can be used for various known applications. Specific examples include, for example, notebook computers, pen input computers, mobile computers, electronic book players, mobile phones, smartphones, mobile faxes, mobile copy, mobile printers, headphone stereos, video movies, LCD TVs, handy cleaners, portable CDs, Mini-disc, walkie-talkie, electronic notebook, calculator, memory card, portable tape recorder, radio, backup power supply, motor, automobile, motorcycle, motorbike, bicycle, lighting equipment, toy, game machine, watch, electric tool, strobe, camera , Load leveling power source, natural energy storage power source and the like.

Claims (16)

A non-aqueous electrolyte solution comprising a lithium salt and a non-aqueous solvent for dissolving the lithium salt, a negative electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte secondary battery comprising a positive electrode,
The non-aqueous electrolyte contains a fluorinated cyclic carbonate represented by the following general formula (1),
The non-aqueous electrolyte secondary battery characterized in that the upper limit operating potential of the positive electrode is 4.75 V or more and 4.90 V or less on the basis of Li / Li ⁺ .

(In general formula (1), R ₁ represents hydrogen, fluorine, or a hydrocarbon group which may have a substituent, and may be the same or different from each other.)   The non-aqueous electrolyte secondary battery according to claim 1, wherein the fluorinated cyclic carbonate represented by the general formula (1) is 4-fluoroethylene carbonate or 4,5-difluoroethylene carbonate. The non-aqueous electrolyte secondary battery according to claim 1 or 2, wherein the non-aqueous electrolyte contains a fluorinated chain carbonate represented by the following general formula (2).

(In General Formula (2), R ₂ represents a hydrocarbon group containing at least one fluorine which may have a substituent, and R ₃ represents a hydrocarbon group which may have a substituent, and they are the same as each other. Or different.)   The non-aqueous electrolyte secondary battery according to claim 3, wherein the fluorinated chain carbonate represented by the general formula (2) is trifluoroethyl methyl carbonate. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the non-aqueous electrolyte contains a cyclic carbonate represented by the following general formula (3).

(In general formula (3), R ₄ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different from each other.)   The non-aqueous electrolyte secondary battery according to claim 5, wherein the cyclic carbonate represented by the general formula (3) is ethylene carbonate or propylene carbonate.   The non-aqueous electrolyte contains a fluorinated cyclic carbonate represented by the following general formula (1) and a fluorinated chain carbonate represented by the following general formula (2), or the following general formula (1) Containing the fluorinated cyclic carbonate represented by the following general formula (2) and the cyclic carbonate represented by the following general formula (3), the total amount of these carbonates is The nonaqueous electrolyte secondary battery according to any one of claims 3 to 6, characterized in that the content is 50% by volume or more in the nonaqueous solvent.   The non-aqueous electrolyte secondary battery according to claim 7, wherein the blending amount of the fluorinated chain carbonate represented by the general formula (2) is 40% by volume or more in the non-aqueous solvent. . A non-aqueous electrolyte solution comprising a lithium salt and a non-aqueous solvent for dissolving the lithium salt, a negative electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte secondary battery comprising a positive electrode,
The non-aqueous electrolyte contains a fluorinated chain carbonate represented by the following general formula (2),
The non-aqueous electrolyte secondary battery characterized in that the upper limit operating potential of the positive electrode is 4.75 V or more and 4.90 V or less on the basis of Li / Li ⁺ .

(In General Formula (2), R ₂ represents a hydrocarbon group containing at least one fluorine which may have a substituent, and R ₃ represents a hydrocarbon group which may have a substituent, and they are the same as each other. Or different.)   The non-aqueous electrolyte secondary battery according to claim 9, wherein the fluorinated chain carbonate represented by the general formula (2) is trifluoroethyl methyl carbonate. The non-aqueous electrolyte secondary battery according to claim 9 or 10, wherein the non-aqueous electrolyte contains a cyclic carbonate represented by the following general formula (3).

(In general formula (3), R ₄ represents hydrogen or a hydrocarbon group which may have a substituent, and may be the same or different from each other.)   The non-aqueous electrolyte secondary battery according to claim 11, wherein the cyclic carbonate represented by the general formula (3) is ethylene carbonate or propylene carbonate.   The non-aqueous electrolyte contains a fluorinated chain carbonate represented by the following general formula (2) and a cyclic carbonate represented by the following general formula (3), and the total amount of these carbonates is non-aqueous The nonaqueous electrolyte secondary battery according to any one of claims 9 to 12, wherein the content is 50% by volume or more in the solvent.   The nonaqueous electrolyte secondary battery according to claim 13, wherein the blending amount of the fluorinated chain carbonate represented by the general formula (2) is 40% by volume or more in the nonaqueous solvent. The said positive electrode contains at least 1 sort (s) selected from the group which consists of a lithium transition metal type compound represented by the following general formula (i)-(iii), The any one of Claims 1-14 characterized by the above-mentioned. The non-aqueous electrolyte secondary battery described in 1.
Li [Li _a M _x Mn _2−x−a ] O _{4 + δ} (i)
(In formula (i), 0 ≦ a ≦ 0.3, 0.4 <x <1.1, −0.5 <δ <0.5 is satisfied, and M is Ni, Cr, Fe, Co and Cu. Represents at least one of transition metals selected from
Li _x M1 _y M2 _z O _2-δ (ii)
(In formula (ii), 1 ≦ x ≦ 1.3, 0 ≦ y ≦ 1, 0 ≦ z ≦ 0.3, −0.1 ≦ δ ≦ 0.
1, M1 represents Ni, Co and / or Mn, M2 represents Fe, Cr, V, Ti, Cu, Ga, Bi, Sn, B, P, Zn, Mg, Ge, Nb, W, It represents at least one element selected from Ta, Be, Al, Ca, Sc and Zr. )
αLi ₂ MO _3. (1-α) LiM′O ₂ (iii)
(In the formula (iii), 0 <α <1 is satisfied, M is at least one metal element having an average oxidation number of +4, and M ′ is at least one metal element having an average oxidation number of +3. Represents.)   The non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode contains at least one negative active material made of graphite particles.