JP6794656B2 - Manufacturing method of non-aqueous electrolyte for secondary batteries, non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary batteries - Google Patents

Description

The present invention relates to a method for producing a non-aqueous electrolyte for a secondary battery, a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery.

Non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries are widely used in personal computers, electronic devices such as communication terminals, automobiles, etc. due to their high energy density. The non-aqueous electrolyte secondary battery generally has a pair of electrodes electrically separated by a separator and a non-aqueous electrolyte interposed between the electrodes, and transfers ions between the two electrodes. It is configured to charge and discharge.

Non-aqueous electrolyte Various additives are added to the non-aqueous electrolyte of the secondary battery for the purpose of improving performance. Specifically, a non-aqueous electrolyte for a secondary battery to which a sulfur-containing compound such as thioketone is added has been proposed in order to increase the capacity retention rate in the charge / discharge cycle (see Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2008-16424 JP-A-2002-198089 Japanese Unexamined Patent Publication No. 2001-185215

However, the non-aqueous electrolyte secondary battery is expected to have higher performance, and there is still room for improvement, such as the need for small battery swelling in the charge / discharge cycle. However, some non-aqueous electrolyte secondary batteries using a conventional non-aqueous electrolyte for secondary batteries to which a sulfur-containing compound is added have an inconvenience that battery swelling is likely to occur in a charge / discharge cycle.

The present invention has been made based on the above circumstances, and an object of the present invention is a non-aqueous electrolyte for a secondary battery capable of suppressing battery swelling in a charge / discharge cycle, and a non-aqueous electrolyte containing the non-aqueous electrolyte. The present invention provides a method for manufacturing an electrolyte secondary battery and a non-aqueous electrolyte secondary battery.

（式（１）中、Ａは、硫黄原子又は酸素原子である。Ｒは、１価の置換基を有していてもよい２価の炭化水素基、又はカルボニル基を含む２価の基である。） The non-aqueous electrolyte for a secondary battery according to one aspect of the present invention, which has been made to solve the above problems, is a non-aqueous electrolyte for a secondary battery in which an electrolyte salt is dissolved in a non-aqueous solvent, and has the following formula (1). Contains the compound represented by.

(In the formula (1), A is a sulfur atom or an oxygen atom. R is a divalent hydrocarbon group which may have a monovalent substituent or a divalent group containing a carbonyl group. is there.)

The non-aqueous electrolyte secondary battery according to another aspect of the present invention is a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode and a non-aqueous electrolyte, and the non-aqueous electrolyte is the non-aqueous electrolyte for the secondary battery. Is used.

The method for producing a non-aqueous electrolyte secondary battery according to another aspect of the present invention is a method for producing a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode and a non-aqueous electrolyte, and the non-aqueous electrolyte is described in the above two. Use a non-aqueous electrolyte for the next battery.

According to the present invention, a method for manufacturing a non-aqueous electrolyte for a secondary battery capable of suppressing battery swelling in a charge / discharge cycle, a non-aqueous electrolyte secondary battery provided with the non-aqueous electrolyte, and a non-aqueous electrolyte secondary battery Can be provided.

FIG. 1 is an external perspective view showing an embodiment of a non-aqueous electrolyte secondary battery according to the present invention. FIG. 2 is a schematic view showing a power storage device configured by assembling a plurality of non-aqueous electrolyte secondary batteries according to the present invention.

Hereinafter, a method for producing a non-aqueous electrolyte for a secondary battery, a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery according to an embodiment of the present invention will be described in detail.

<Non-aqueous electrolyte for secondary batteries>
The non-aqueous electrolyte for a secondary battery according to an embodiment of the present invention (hereinafter, may be simply referred to as “non-aqueous electrolyte”) is a non-aqueous electrolyte for a secondary battery in which an electrolyte salt is dissolved in a non-aqueous solvent. It contains a compound represented by the following formula (1). The above compounds may be used alone or in admixture of two or more.

<Compound represented by formula (1)>

In formula (1), A is a sulfur atom or an oxygen atom. R is a divalent hydrocarbon group which may have a monovalent substituent or a divalent group containing a carbonyl group.

By containing such a compound, the non-aqueous electrolyte for a secondary battery can suppress battery swelling in a charge / discharge cycle. The reason for this is not clear, but it is presumed that, for example, the decomposition of such a compound on the electrode surface during the first charge forms a good film on the electrode surface that can withstand the charge / discharge cycle. That is, it is presumed that the decomposition of non-aqueous electrolyte constituents such as additives remaining in the charge / discharge cycle causes the formation of low molecular weight compounds that are easily gasified, which is usually the cause of battery swelling. .. On the other hand, in the non-aqueous electrolyte for a secondary battery, the good coating formed by the decomposition of the above compound on the electrode surface suppresses the decomposition of the non-aqueous electrolyte component during the charge / discharge cycle, and as a result, Since the production of low molecular weight compounds that are easily gasified is suppressed, it is presumed that battery swelling in the charge / discharge cycle can be suppressed.

In addition, the non-aqueous electrolyte for a secondary battery can also increase the capacity retention rate in the charge / discharge cycle. It is presumed that such an effect is also due to the fact that the good film formed by the decomposition of the compound on the electrode surface suppresses the decomposition of the non-aqueous electrolyte constituent components during the charge / discharge cycle.

The above-mentioned A is a sulfur atom or an oxygen atom, but an oxygen atom is preferable. When A is an oxygen atom, especially when applied to a non-aqueous electrolyte secondary battery in which a charging condition (for example, 4.35 V) having a relatively high upper limit voltage is adopted, it is possible to suppress battery swelling in the charge / discharge cycle. In addition, the capacity retention rate in the charge / discharge cycle can be increased. On the other hand, when A is a sulfur atom, especially when applied to a non-aqueous electrolyte secondary battery in which a charging condition (for example, 4.2 V) having a relatively low upper limit voltage is adopted, the battery swells in the charge / discharge cycle. In addition to suppression, the capacity retention rate in the charge / discharge cycle can be increased.

The R is a divalent hydrocarbon group which may have a monovalent substituent or a divalent group containing a carbonyl group. The R forms a monocyclic or polycyclic heterocyclic structure together with the two sulfur atoms to which the R is bonded and the carbon chain (-SC = CS-).

Examples of the divalent hydrocarbon group include a divalent aliphatic hydrocarbon group and a divalent aromatic hydrocarbon group. Examples of the divalent aliphatic hydrocarbon group include a divalent aliphatic chain hydrocarbon group and a divalent aliphatic cyclic hydrocarbon group (aliphatic group).

As a divalent aliphatic chain hydrocarbon group,
Alkanediyl groups such as methanediyl group, ethanediyl group, propanediyl group and butanjiyl group,
Arkendiyl groups such as ethendyl groups, propendil groups, butendiyl groups,
Examples thereof include an alkyndiyl group such as an ethyndiyl group, a propindyl group, and a butindiyl group.

As a divalent aliphatic cyclic hydrocarbon group,
Cycloalkandyl groups such as cyclopentanediyl group and cyclohexanediyl group,
Cycloalkenediyl groups such as cyclopentenediyl group and cyclohexenediyl group can be mentioned.

As a divalent aromatic hydrocarbon group,
Examples thereof include a benzenediyl group, a naphthalenediyl group, and a biphenylene group.

Examples of the monovalent substituent include a halogen atom (fluorine atom, chlorine atom, etc.), hydroxy group, carboxy group, nitro group, cyano group, amino group, alkoxy group (methoxy group, ethoxy group, propoxy group, etc.) and the like. be able to.

Examples of the divalent group containing a carbonyl group include a group consisting of only a carbonyl group (-CO-) and a group in which a carbonyl group and another divalent group are bonded. Examples of the other divalent group include the above-mentioned divalent hydrocarbon group and divalent heteroatom-containing group. Examples of the divalent heteroatom-containing group include -O-, -S-, -SO-, -SO _2- , -SO ₂ O-, -SO _3- , -NH- and the like.

The carbon number of R is not particularly limited, and the lower limit thereof may be 1 or 2. Further, this upper limit may be, for example, 20, may be 8, or may be 4.

The R is preferably a divalent aliphatic hydrocarbon group having 1 to 8 carbon atoms, a carbonyl group, or a combination thereof. As the upper limit of the number of carbon atoms of the divalent aliphatic hydrocarbon group, 6 is more preferable, 4 is more preferable, and 2 is particularly preferable. Further, the lower limit of the number of carbon atoms can be set to 2. Among the above divalent aliphatic hydrocarbon groups, a divalent aliphatic chain hydrocarbon group is preferable, an alkanediyl group is more preferable, an ethanediyl group is further preferable, and an ethane-1,2-diyl group (-CH ₂₎ is preferable. CH _2- ) is particularly preferable. Examples of the group of the combination of the divalent aliphatic hydrocarbon group and the carbonyl group include -CH ₂ COCH _2- , -CH ₂ CH ₂ CO- and the like. When R is such a group, the function of suppressing battery swelling in the charge / discharge cycle can be more effectively exhibited. Further, the compound represented by the formula (1) in which R is such a group is relatively easy to synthesize and obtain, and can increase the productivity of the non-aqueous electrolyte and suppress the production cost.

As the R, a divalent group containing a carbonyl group is also preferable, and a carbonyl group is more preferable. When R is a divalent group containing a carbonyl group, battery swelling in the charge / discharge cycle can be suppressed more effectively.

Further, in R, the number of atoms in the molecular chain between the two bonding steps is preferably 1 or 2. In this case, a ring structure having 5 or 6 ring members is formed together with two sulfur atoms to which R is bonded. It is presumed that such a ring structure has high stability and a better film is formed. Further, since the compound having such a ring structure is relatively easy to synthesize, the productivity can be increased and the production cost can be suppressed. Examples of the group having one atomic number in the molecular chain between the two bonding steps include a carbonyl group, a methanediyl group, and an ethane-1,1-diyl group. Examples of the group having 2 atoms in the molecular chain between the two bonding steps include an ethane-1,2-diyl group, a butane-2,3-diyl group, and a cyclohexane-1,2-diyl group.

Examples of the compound represented by the above formula (1) include compounds represented by the following formulas (1-1) to (1-18).

The lower limit of the content of the compound in the non-aqueous electrolyte is not particularly limited, but is preferably 0.1% by mass, more preferably 0.2% by mass, and even more preferably 0.5% by mass. By setting the content of the compound to the above lower limit or more, battery swelling in the charge / discharge cycle can be effectively suppressed. The upper limit of this content is not particularly limited, but is, for example, 5% by mass and may be 2% by mass.

<Non-aqueous solvent>
As the non-aqueous solvent, a known non-aqueous solvent usually used as a non-aqueous solvent for a general non-aqueous electrolyte for a secondary battery can be used. Examples of the non-aqueous solvent include cyclic carbonates, chain carbonates, esters, ethers, amides, sulfones, lactones, nitriles and the like. Among these, it is preferable to use at least cyclic carbonate or chain carbonate, and it is more preferable to use cyclic carbonate and chain carbonate in combination. When the cyclic carbonate and the chain carbonate are used in combination, the volume ratio of the cyclic carbonate to the chain carbonate (cyclic carbonate: chain carbonate) is not particularly limited, but is, for example, 5:95 or more and 50:50 or less. Is preferable.

Examples of the cyclic carbonate include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), vinylethylene carbonate (VEC), chloroethylene carbonate, fluoroethylene carbonate (FEC), and difluoroethylene. Examples thereof include carbonate (DFEC), styrene carbonate, catechol carbonate, 1-phenylvinylene carbonate, 1,2-diphenylvinylene carbonate, and among these, EC is preferable.

Examples of the chain carbonate include diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diphenyl carbonate and the like, and among these, EMC is preferable.

<Electrolyte salt>
As the electrolyte salt, a known electrolyte salt usually used as an electrolyte salt of a general non-aqueous electrolyte for a secondary battery can be used. Examples of the electrolyte salt include lithium salt, sodium salt, potassium salt, magnesium salt, onium salt and the like, but lithium salt is preferable.

Examples of the lithium salt include inorganic lithium salts such as LiPF ₆ , LiPO ₂ F ₂ , LiBF ₄ , LiClO ₄ , LiN (SO ₂ F) ₂ , LiSO ₃ CF ₃ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO). ₂ C ₂ F ₅ ) ₂ , LiN (SO ₂ CF ₃ ) (SO ₂ C ₄ F ₉ ), LiC (SO ₂ CF ₃ ) ₃ , LiC (SO ₂ C ₂ F ₅ ) _{3 and} other fluorinated hydrocarbon groups Lithium salt having the above can be mentioned. Among these, an inorganic lithium salt is preferable, and LiPF ₆ is more preferable.

The lower limit of the content of the electrolyte salt in the non-aqueous electrolyte is preferably 0.1 M, more preferably 0.3 M, further preferably 0.5 M, and particularly preferably 0.7 M. On the other hand, the upper limit is not particularly limited, but is preferably 2.5M, more preferably 2M, and even more preferably 1.5M.

The non-aqueous electrolyte may contain components other than the above-mentioned compound, the above-mentioned non-aqueous solvent, and the above-mentioned electrolyte salt as long as the effects of the present invention are not impaired. Examples of the other components include various additives contained in a general non-aqueous electrolyte for a secondary battery. However, the content of these other components is preferably 5% by mass or less, and more preferably 1% by mass or less.

The non-aqueous electrolyte can be obtained by adding the electrolyte salt and the compound to the non-aqueous solvent and dissolving them.

<Non-aqueous electrolyte secondary battery>
The non-aqueous electrolyte secondary battery according to an embodiment of the present invention includes a positive electrode, a negative electrode, and a non-aqueous electrolyte. The positive electrode and the negative electrode usually form electrode bodies that are alternately superposed by stacking or winding through a separator. The electrode body is housed in a case, and the case is filled with the non-aqueous electrolyte. In the non-aqueous electrolyte secondary battery, the above-mentioned non-aqueous electrolyte for a secondary battery is used as the non-aqueous electrolyte. The non-aqueous electrolyte is interposed between the positive electrode and the negative electrode. Further, as the above case, a known aluminum case or the like which is usually used as a case of a non-aqueous electrolyte secondary battery can be used.

According to the non-aqueous electrolyte secondary battery, the battery swelling in the charge / discharge cycle can be suppressed by using the non-aqueous electrolyte containing the above compound. The upper limit voltage for charging the non-aqueous electrolyte secondary battery can be, for example, 4.2 V or more, and further can be 4.35 V or more. On the other hand, the upper limit of the charge upper limit voltage is, for example, 5.0 V, and may be 4.5 V.

<Positive electrode>
The positive electrode has a positive electrode base material and a positive electrode active material layer arranged directly on the positive electrode base material or via an intermediate layer.

The positive electrode base material has conductivity. As the material of the base material, metals such as aluminum, titanium, tantalum, and stainless steel or alloys thereof are used. Among these, aluminum and aluminum alloys are preferable from the viewpoint of balance of potential resistance, high conductivity and cost. Further, as a form of forming the positive electrode base material, a foil, a vapor-deposited film and the like can be mentioned, and the foil is preferable from the viewpoint of cost. That is, an aluminum foil is preferable as the positive electrode base material. Examples of aluminum or aluminum alloy include A1085P and A3003P specified in JIS-H-4000 (2014).

The intermediate layer is a coating layer on the surface of the positive electrode base material, and contains conductive particles such as carbon particles to reduce the contact resistance between the positive electrode base material and the positive electrode active material layer. The composition of the intermediate layer is not particularly limited, and can be formed by, for example, a composition containing a resin binder and conductive particles. Incidentally, to have a "conductive" means that the volume resistivity is measured according to JIS-H-0505 (1975 years) is not more than 10 ⁷ Ω · cm, and "non-conductive" means that the volume resistivity is 10 ⁷ Ω · cm greater.

The positive electrode active material layer is formed from a so-called positive electrode mixture containing a positive electrode active material. Further, the positive electrode mixture forming the positive electrode active material layer contains optional components such as a conductive agent, a binder (binding agent), a thickener, and a filler, if necessary.

Examples of the positive electrode active material include composite oxides represented by Li _x MO _y (M represents at least one kind of transition metal) (Li _x CoO ₂ and Li _x NiO having a layered α-NaFeO type ₂ crystal structure). ₂ , Li _x MnO ₃ , Li _x Ni _α Co _(1-α) O ₂ , Li _x Ni _α Mn _β Co _(1-α-β) O _2, etc., Li _x Mn ₂ O ₄ having a spinel type crystal structure , Li _x Ni _α Mn _(2-α) O ₄ etc.), Li _w Me _x (XO _y ) _z (Me represents at least one kind of transition metal, and X represents, for example, P, Si, B, V, etc.) Examples thereof include polyanionic compounds represented by (LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ , Li ₃ V ₂ (PO ₄ ) ₃ , Li ₂ MnSiO ₄ , Li ₂ CoPO ₄ F, etc.). The elements or polyanions in these compounds may be partially substituted with other elements or anion species. In the positive electrode active material layer, one of these compounds may be used alone, or two or more of these compounds may be mixed and used.

The conductive agent is not particularly limited as long as it is a conductive material that does not adversely affect the battery performance. Examples of such a conductive agent include natural or artificial graphite, carbon black such as furnace black, acetylene black, and Ketjen black, metal, and conductive ceramics. Examples of the shape of the conductive agent include powder and fibrous.

Examples of the binder (binding agent) include fluororesins (polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc.), thermoplastic resins such as polyethylene, polypropylene, and polyimide; ethylene-propylene-diene rubber (EPDM), Elastomers such as sulfonated EPDM, styrene-butadiene rubber (SBR), and fluororubber; and thermoplastic polymers can be mentioned.

Examples of the thickener include polysaccharide polymers such as carboxymethyl cellulose (CMC) and methyl cellulose. When the thickener has a functional group that reacts with lithium, it is preferable to deactivate the functional group by methylation or the like in advance.

The filler is not particularly limited as long as it does not adversely affect the battery performance. Examples of the main component of the filler include polyolefins such as polypropylene and polyethylene, silica, alumina, zeolite, glass, carbon and the like.

<Negative electrode>
The negative electrode has a negative electrode base material and a negative electrode active material layer arranged directly on the negative electrode base material or via an intermediate layer. The intermediate layer may have the same structure as the intermediate layer of the positive electrode.

The negative electrode base material may have the same structure as the positive electrode base material, but as the material, a metal such as copper, nickel, stainless steel, nickel-plated steel or an alloy thereof is used, and copper or a copper alloy is used. preferable. That is, copper foil is preferable as the negative electrode base material. Examples of the copper foil include rolled copper foil and electrolytic copper foil.

The negative electrode active material layer is formed from a so-called negative electrode mixture containing a negative electrode active material. Further, the negative electrode mixture forming the negative electrode active material layer contains optional components such as a conductive agent, a binder (binder), a thickener, and a filler, if necessary. As the optional component such as the conductive agent, the binder, the thickener, and the filler, the same one as that of the positive electrode active material layer can be used.

As the negative electrode active material, a material capable of occluding and releasing lithium ions is usually used. Specific negative electrode active materials include, for example, metals or semi-metals such as Si and Sn; metal oxides or semi-metal oxides such as Si oxide and Sn oxide; polyphosphoric acid compounds; graphite and amorphous. Examples thereof include carbon materials such as carbon (graphitizable carbon or non-graphitizable carbon).

Further, the negative electrode mixture (negative electrode active material layer) is a typical non-metal element such as B, N, P, F, Cl, Br, I, Li, Na, Mg, Al, K, Ca, Zn, Ga, Ge. It may contain a typical metal element such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Zr, Ta, Hf, Nb, W and the like.

<Separator>
As the material of the separator, for example, a woven fabric, a non-woven fabric, a porous resin film or the like is used. Among these, a porous resin film is preferable. As the main component of the porous resin film, polyolefins such as polyethylene and polypropylene are preferable from the viewpoint of strength. Further, a porous resin film obtained by combining these resins with a resin such as aramid or polyimide may be used.

FIG. 1 shows a schematic view of a rectangular non-aqueous electrolyte secondary battery 1 which is an embodiment of the non-aqueous electrolyte secondary battery. The figure is a perspective view of the inside of the container. In the non-aqueous electrolyte secondary battery 1 shown in FIG. 1, the electrode group 2 is housed in the battery container 3. The electrode group 2 is formed by winding a positive electrode having a positive electrode active material and a negative electrode having a negative electrode active material through a separator. The positive electrode is electrically connected to the positive electrode terminal 4 via the positive electrode lead 4', and the negative electrode is electrically connected to the negative electrode terminal 5 via the negative electrode lead 5'.

The configuration of the non-aqueous electrolyte secondary battery is not particularly limited, and examples thereof include a cylindrical battery, a square battery (rectangular battery), and a flat battery. The present invention can also be realized as a power storage device including a plurality of the above-mentioned non-aqueous electrolyte secondary batteries. An embodiment of the power storage device is shown in FIG. In FIG. 2, the power storage device 30 includes a plurality of power storage units 20. Each power storage unit 20 includes a plurality of non-aqueous electrolyte secondary batteries 1. The power storage device 30 can be mounted as a power source for automobiles such as electric vehicles (EV), hybrid electric vehicles (HEV), and plug-in hybrid vehicles (PHEV).

<Manufacturing method of non-aqueous electrolyte secondary battery>
The method for producing a non-aqueous electrolyte secondary battery according to an embodiment of the present invention is a method for producing a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, and the secondary is the non-aqueous electrolyte. It is characterized by using a non-aqueous electrolyte for batteries. The manufacturing method includes, for example, a step of accommodating a positive electrode and a negative electrode (electrode body) in a case, and a step of injecting the non-aqueous electrolyte into the case.

The above injection can be performed by a known method. After injection, a non-aqueous electrolyte secondary battery can be obtained by sealing the injection port. Details of each element constituting the non-aqueous electrolyte secondary battery obtained by the manufacturing method are as described above. According to the method for producing a non-aqueous electrolyte secondary battery, a non-aqueous electrolyte secondary battery in which battery swelling in a charge / discharge cycle is suppressed can be produced by using a non-aqueous electrolyte containing the above compound.

<Other Embodiments>
The present invention is not limited to the above-described embodiment, and can be implemented in various modifications and improvements in addition to the above-described embodiment. For example, it is not necessary to provide an intermediate layer in the positive electrode or the negative electrode. Further, for example, when a polymer solid electrolyte is used as the non-aqueous electrolyte, the above-mentioned injection step may not be provided in the method for producing a non-aqueous electrolyte secondary battery of the present invention.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

The compounds used in Examples and Comparative Examples are shown below.
-4,5-Ethylenedithio-1,3-dithiol-2-thione (Compound A represented by the following formula (A))
-4,5-Ethylenedithio-1,3-dithiol-2-one (Compound B represented by the following formula (B))
1,3,4,5-Tetrathiapentalene-2,5-dione (Compound C represented by the following formula (C))
1,3-Dithiol-2-thione (compound a represented by the following formula (a))
-Ethylene trithiocarbonate (compound b represented by the following formula (b))
4,5-bis (methylthio) -1,3-dithiol-2-thione (compound c represented by the following formula (c))
4,5-bis (methylthio) -1,3-dithiol-2-one (compound d represented by the following formula (d))

[Example 1]
(Preparation of non-aqueous electrolyte)
LiPF ₆ was dissolved at a concentration of 1.0 M in a solvent in which EC and EMC were mixed at a volume ratio of 30:70. To this, 4,5-ethylenedithio-1,3-dithiol-2-thione (the above compound A) was further added as an additive so as to be 1.0% by mass to obtain the non-aqueous electrolyte of Example 1. It was.

(Manufacturing of non-aqueous electrolyte secondary battery)
A positive electrode plate having LiNi _1/3 Co _1/3 Mn _1/3 O ₂ having an α-NaFeO type ₂ crystal structure as a positive electrode active material was prepared. In addition, a negative electrode plate using graphite as a negative electrode active material was produced. Next, the positive electrode plate and the negative electrode plate were laminated via a separator made of a polyethylene microporous membrane, and wound into a flat shape to prepare an electrode body. This electrode body was housed in a square electric tank can made of aluminum, and a positive electrode terminal and a negative electrode terminal were attached. After injecting the non-aqueous electrolyte into the inside of this container (square electric tank can), the container was sealed to obtain a non-aqueous electrolyte secondary battery (lithium ion secondary battery).

[Examples 2 to 3 and Comparative Examples 1 to 5]
The non-aqueous electrolytes of Examples 2 to 3 and Comparative Examples 1 to 5 and non-aqueous electrolytes in the same manner as in Example 1 except that the types of additives used were listed in Table 1 or were not added. A water electrolyte secondary battery was obtained.

[Evaluation]
[Evaluation at charging upper limit voltage 4.2V]
(Charge / discharge cycle test)
Each of the obtained non-aqueous electrolyte secondary batteries was initially charged and discharged at 25 ° C. with a charge upper limit voltage of 4.2 V and a discharge end voltage of 2.75 V. Next, constant current voltage charging was performed in a constant temperature bath at 45 ° C. with a charging current of 750 mA, a charging upper limit voltage of 4.20 V, and a total charging time of 3 hours, and then a rest period of 10 minutes was provided. Then, a constant current discharge was performed with a discharge current of 750 mA and a discharge end voltage of 2.75 V, and then a rest period of 10 minutes was provided. This charge / discharge was carried out for 300 cycles. The ratio of the discharge capacity after 300 cycles to the discharge capacity of the first cycle in this charge / discharge cycle test was determined as the "capacity retention rate (%)". The results are shown in Table 1.

(Measurement of battery swelling)
The battery thickness in the discharged state after the initial charge / discharge and after 300 cycles in the charge / discharge cycle test was measured. Table 1 shows the thickness of each non-aqueous electrolyte secondary battery when the thickness of the non-aqueous electrolyte secondary battery of Comparative Example 1 is 100%.

[Evaluation at charging upper limit voltage 4.35V]
(Charge / discharge cycle test)
Each non-aqueous electrolyte secondary battery having a design capacity of 850 mAh was initially charged and discharged at 25 ° C. with a charge upper limit voltage of 4.35 V and a discharge end voltage of 2.75 V. Next, constant current voltage charging was performed in a constant temperature bath at 45 ° C. with a charging current of 850 mA, a charging upper limit voltage of 4.35 V, and a total charging time of 3 hours, and then a rest period of 10 minutes was provided. Then, a constant current discharge was performed with a discharge current of 850 mA and a discharge end voltage of 2.75 V, and then a rest period of 10 minutes was provided. This charge / discharge was carried out for 50 cycles. The ratio of the discharge capacity after 50 cycles to the discharge capacity of the first cycle in this charge / discharge cycle test was determined as the "capacity retention rate (%)". The results are shown in Table 1.

(Measurement of battery swelling)
The battery thickness in the discharged state after the initial charge / discharge and after 50 cycles in the charge / discharge cycle test was measured. Table 1 shows the thickness of each non-aqueous electrolyte secondary battery when the thickness of the non-aqueous electrolyte secondary battery of Comparative Example 1 is 100%.

As shown in Table 1 above, the non-aqueous electrolyte secondary batteries of Examples 1 to 3 provided with the non-aqueous electrolyte to which the compound represented by the above formula (1) is added are the compounds represented by the formula (1). It can be seen that the battery swelling after the charge / discharge cycle is equal to or less than that of the non-aqueous electrolyte secondary battery of Comparative Example 1 in which the above is not added. On the other hand, the non-aqueous electrolyte secondary batteries of Comparative Examples 2 to 5 to which a sulfur-containing compound other than the compound represented by the above formula (1) was added were charged as compared with the non-aqueous electrolyte secondary batteries of Comparative Example 1. It can be seen that the battery swelling after the discharge cycle is equal to or greater than that, and the battery swelling after the charge / discharge cycle is larger than that of the non-aqueous electrolyte secondary batteries of Examples 1 to 3. Further, the non-aqueous electrolyte secondary batteries of Examples 1 to 3 have a high capacity retention rate in the charge / discharge cycle, and in particular, the non-aqueous electrolyte secondary battery of Example 1 has a charge upper limit voltage of 4.2 V. , It can be seen that the non-aqueous electrolyte secondary batteries of Examples 2 and 3 have a high capacity retention rate in the charge / discharge cycle of the charge upper limit voltage of 4.35 V.

The present invention can be applied to a non-aqueous electrolyte secondary battery used as a power source for a personal computer, an electronic device such as a communication terminal, an automobile, and a non-aqueous electrolyte for a secondary battery provided therein.

(Explanation of sign)
1 Non-aqueous electrolyte secondary battery 2 Electrode body 3 Battery container 4 Positive terminal 4'Positive lead 5 Negative terminal 5'Negative lead 20 Power storage unit 30 Power storage device

Claims (7)

A non-aqueous electrolyte for secondary batteries in which an electrolyte salt dissolves in a non-aqueous solvent.
A non-aqueous electrolyte for a secondary battery containing a compound represented by the following formula (1) (excluding those corresponding to the following (A) to (E)).

(In the formula (1), A is a sulfur atom or an oxygen atom. R is a divalent hydrocarbon group which may have a monovalent substituent or a divalent group containing a carbonyl group. is there.)
(A) 0.1 wt% to 3 wt% of 1,3-dithiolo [4,5-d] [1,3] dithiol-2,5-dione and 0.1 wt% to 10 wt% of Those containing fluoroethylene carbonate (B) 3% by weight 1,3-dithiolo [4,5-d] [1,3] Dithiol-2,5-dione (C) 5% by weight 1 , 3-Dithiolo [4,5-d] [1,3] Dithiol-2,5-dione and 5% by weight fluoroethylene carbonate (D) 0.5% by weight 1,3-dithiolo [ 4,5-d] [1,3] Dithiol-2,5-dione and 15% by weight fluoroethylene carbonate (E) 0.5% by weight of 4,5-ethylenedithio-1,3- Those containing dithiol-2-thione R in the above formula (1) is formed from a divalent aliphatic hydrocarbon group having 1 to 8 carbon atoms, a carbonyl group, or a divalent aliphatic hydrocarbon group having 1 to 8 carbon atoms and a carbonyl group. The non-aqueous electrolyte for a secondary battery according to claim 1, which is a base. The non-aqueous electrolyte for a secondary battery according to claim 1 or 2, wherein A in the above formula (1) is an oxygen atom. A non-aqueous electrolyte secondary battery having a positive electrode, a negative electrode, and a non-aqueous electrolyte.
A non-aqueous electrolyte secondary battery in which the non-aqueous electrolyte for a secondary battery according to claim 1, 2, or 3 is used as the non-aqueous electrolyte. The non-aqueous electrolyte secondary battery according to claim 4, wherein the upper limit voltage for charging is 4.2 V or more. The non-aqueous electrolyte secondary battery according to claim 4, wherein the upper limit voltage for charging is 4.35 V or more. A method for manufacturing a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte.
A method for producing a non-aqueous electrolyte secondary battery, which uses the non-aqueous electrolyte for a secondary battery according to claim 1, 2, or 3 as the non-aqueous electrolyte.

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