JP6096595B2 - Non-aqueous electrolyte secondary battery and method of manufacturing the battery - Google Patents

Description

  The present invention relates to a secondary battery (non-aqueous electrolyte secondary battery) provided with a non-aqueous electrolyte. Specifically, the present invention relates to a battery that includes an alkyne sulfonic acid compound in a non-aqueous electrolyte during battery construction (in the state of the assembly).

  In recent years, non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries and nickel metal hydride batteries have been used as so-called portable power supplies and vehicle drive power supplies for personal computers and portable terminals. In particular, a lithium ion secondary battery that is lightweight and obtains a high energy density is preferably used as a high-output power source for driving vehicles such as electric vehicles and hybrid vehicles.

  In such a non-aqueous electrolyte secondary battery, a part of the non-aqueous electrolyte is decomposed at the time of initial charge, and a film made of the decomposition product is formed on the surface of the negative electrode active material. Such a coating suppresses the decomposition of the non-aqueous electrolyte accompanying subsequent charging / discharging, so that the durability (for example, cycle characteristics) of the battery can be improved. Patent documents 1 and 2 are mentioned as a technique relevant to this. For example, Patent Document 1 discloses a non-aqueous electrolyte secondary battery containing alkyne sulfonic acids in a ratio of 0.01 wt% to 20 wt% in the non-aqueous electrolyte.

JP 2000-195545 A JP 2010-13369 A

  In Patent Document 1, the alkynesulfonic acid is reduced and decomposed on the negative electrode surface prior to the organic solvent at the time of charging to form a passive film on the negative electrode surface, thereby reducing the organic solvent in the nonaqueous electrolytic solution. It is described that it can be further suppressed (paragraph 0015 of Patent Document 1). However, according to the study by the present inventors, when the technique of Patent Document 1 is applied to a battery (for example, a vehicle-mounted battery) that can be used in a wide range of temperature environments (particularly from room temperature to −30 ° C.), There was room for further improvement. That is, when the amount of alkyne sulfonic acid added is determined with respect to the entire non-aqueous electrolyte, it is difficult to appropriately cope with changes in other design parameters (for example, the weight per unit area, thickness, density, etc. of the negative electrode active material layer). In some cases, the coating on the surface of the negative electrode is insufficient, resulting in a decrease in durability, and in other cases, the coating is excessive, resulting in an increase in battery resistance. Such an increase in resistance is particularly noticeable in a low temperature environment, and in a battery (for example, an on-vehicle battery) that requires a high output density in such a low temperature environment, the amount of alkyne sulfonic acid added is further optimized. Is required.

  The present invention has been made in view of such circumstances, and the purpose thereof is to more suitably exhibit the effect of alkyne sulfonic acid addition, and for example, it can exhibit higher battery characteristics even in a low temperature environment (for example, To provide a non-aqueous electrolyte secondary battery (high power density) and an assembly for the battery. Another related object is that even when the design parameters such as the properties of the negative electrode active material are changed, a suitable amount of alkynesulfonic acid can be easily determined and added, and the productivity and reproducibility are excellent. It is providing the manufacturing method of a battery.

The inventors of the present invention have made extensive studies and have found a means for solving the problem and completed the present invention. According to the present invention, a non-aqueous electrolyte secondary battery assembly is provided. Such an assembly includes a positive electrode including a positive electrode active material layer, a negative electrode including a negative electrode active material layer, and a non-aqueous electrolyte containing an alkyne sulfonic acid compound in a battery case. The non-aqueous electrolyte solution contains the alkyne sulfonic acid compound in an amount of 0.012 g or more and 0.023 g or less per 1 cm ³ of the void volume in the negative electrode active material layer.

When 0.012 g or more of an alkyne sulfonic acid compound is contained per 1 cm ³ of the void volume in the negative electrode active material layer, a sufficient amount of a film can be formed on the surface of the negative electrode active material by the subsequent charging treatment. The interface between (typically graphite particles) and the non-aqueous electrolyte can be stabilized. For this reason, decomposition | disassembly of the non-aqueous electrolyte in subsequent charging / discharging can be suppressed suitably. In particular, coatings containing sulfur atoms derived from alkyne sulfonic acid compounds are excellent in thermal stability, so they do not easily decompose or deteriorate even in high-temperature environments, and have high durability (for example, high-temperature storage characteristics and high-temperature charge / discharge cycle characteristics). Can be realized.
Moreover, it is possible to prevent an excessive coating from being formed on the surface of the negative electrode active material by setting the amount of the alkyne sulfonic acid compound to be 0.023 g or less per 1 cm ³ of the void volume in the negative electrode active material layer. it can. For this reason, the increase in resistance accompanying the formation of the film can be suppressed. For example, a reaction field of charge carriers can be suitably secured even in a low temperature environment, and high input / output characteristics can be realized.
Therefore, an assembly in which the amount of alkyne sulfonic acid compound added is in the above range is preferably a non-aqueous electrolyte secondary battery that can exhibit high battery characteristics (for example, input / output characteristics and durability) under a wide range of temperature environments. Can be realized.

The “volume of voids in the negative electrode active material layer” can be obtained by subtracting the total volume of each constituent material from the apparent volume. More specifically, for example, when the negative electrode active material layer includes a negative electrode active material, a binder, and a thickener as constituent materials, the following formula: volume of voids in negative electrode active material layer (V) = negative electrode active material Apparent volume of layer − {(weight of negative electrode active material / true density of negative electrode active material) + (weight of binder for negative electrode / true density of binder for negative electrode) + (weight of thickener for negative electrode / thickness for negative electrode) The true density of the agent)}.
The “apparent volume of the negative electrode active material layer” can be calculated by the product of the area S (cm ² ) and the thickness T (cm) in plan view. The “area S in plan view” can be obtained, for example, by cutting the negative electrode active material layer into a square or a rectangle with a punching machine or a cutter. The “thickness T” can be measured by, for example, a micrometer or a thickness meter (for example, a rotary caliper meter). The “true density” can be measured by a density measuring device such as a general constant volume expansion method (gas displacement pycnometer method).

Alternatively, the “volume of voids in the negative electrode active material layer” can be measured by a general mercury porosimeter. Specifically, first, the negative electrode active material layer taken out by disassembling the battery is immersed in an appropriate solvent (for example, EMC), and then cut into an appropriate size and collected as a measurement sample. Next, the measurement sample is immersed in mercury in a vacuumed state, and the pressure applied to the mercury is increased in this state. Then, mercury gradually enters into a smaller space (pore). Therefore, based on the relationship between the pressure applied to mercury and the amount of mercury intruded, the size of the voids (pore diameter) and the distribution of the volume (pore volume) in the anode active material layer can be measured. it can. For example, when a mercury porosimeter “Autopore III 9410” manufactured by Shimadzu Corporation is used, the volume distribution of voids corresponding to pore diameters in the range of 50 μm to 0.003 μm can be obtained by measuring in a pressure range of 4 psi to 60000 psi. I can grasp it. The total pore volume (total pore volume (cm ³ )) obtained by such measurement can be defined as the “volume of voids in the negative electrode active material layer”.

  In this specification, “non-aqueous electrolyte secondary battery” refers to a non-aqueous electrolyte that is liquid at room temperature (for example, 25 ° C.) (typically, an electrolyte containing a supporting salt in a non-aqueous solvent). A battery equipped with Further, in this specification, the “lithium ion secondary battery” refers to a secondary battery that uses lithium ions as a charge carrier and is charged and discharged by movement of lithium ions between the positive and negative electrodes.

  The negative electrode active material layer contains at least a negative electrode active material. In a preferred embodiment, the negative electrode active material layer contains natural graphite as the negative electrode active material. Since natural graphite has higher crystallinity than other negative electrode active material, it is excellent in energy density and conductivity. On the other hand, the interface with a non-aqueous electrolyte (for example, a carbonate-based non-aqueous solvent) tends to become unstable, which may reduce the durability of the battery. Therefore, it is particularly preferable to apply the technique disclosed here.

In a preferred embodiment, the thickness per side of the negative electrode active material layer is 30 μm or more and 100 μm or less. In another preferable embodiment, the density of the negative electrode active material layer is 1 g / cm ³ or more and 1.5 g / cm ³ or less. The negative electrode active material layer that satisfies at least one (preferably both) properties among the above can maintain the interface with the non-aqueous electrolyte more suitably, and has a higher level of energy density, durability, and output characteristics. It can be compatible.

In a preferred embodiment, a high dielectric constant solvent and a low viscosity solvent are mixed and used as the nonaqueous solvent constituting the nonaqueous electrolytic solution. By using such a mixed solvent, it is possible to achieve high electrical conductivity and use in a wide temperature range. Examples of the high dielectric constant solvent include ethylene carbonate (EC). Examples of the low viscosity solvent include dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC). Moreover, in another suitable one aspect | mode, ethylene carbonate accounts for 20 volume% or more and 40 volume% or less of the whole nonaqueous solvent. As a result, the reduction potential (vs. Li / Li ⁺ ) of the nonaqueous solvent can be kept sufficiently low, and a good quality (low resistance) film can be formed on the surface of the negative electrode active material by the subsequent charging process. .

式（Ｉ）において、Ｒ^１は、炭素原子数１〜１２の直鎖状または分岐状のアルキル基、炭素原子数３〜６のシクロアルキル基、炭素原子数６〜１２のアリール基、または炭素原子数１〜１０のパーフルオロアルキル基である。また、Ｒ^２，Ｒ^３，Ｒ^４，Ｒ^５は、それぞれ独立して、水素原子、または炭素原子数１〜４の直鎖状または分岐状のアルキル基である。 In a preferred embodiment, the alkyne sulfonic acid compound is a compound represented by the following formula (I). By including a compound having a triple bond at an intermediate position of the molecular structure as the alkyne sulfonic acid compound, a high-quality film can be more stably formed on the surface of the negative electrode active material.

In the formula (I), R ¹ is a linear or branched 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 carbon. A perfluoroalkyl group having 1 to 10 atoms. R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms.

In a preferred embodiment, R ¹ in the above formula (I) is a methyl group (CH ₃ ). In another preferred embodiment, R ^{2 to} R ⁵ in the above formula (I) are all hydrogen atoms. An example of such an alkyne sulfonic acid compound is 2-butyne-1,4-diol di (methanesulfonate) represented by the following formula (II).

The present invention also provides a method for producing a non-aqueous electrolyte secondary battery. Such a production method comprises the following steps:
(1) preparing a negative electrode provided with a negative electrode active material layer;
(2) Obtaining the volume (cm ³ ) of voids in the negative electrode active material layer;
(3) preparing a non-aqueous electrolyte containing an alkyne sulfonic acid compound;
Here, the alkynesulfonic acid compound in an amount of 0.012 g or more and 0.023 g or less per 1 cm ³ of the void volume in the obtained negative electrode active material layer is included in the non-aqueous electrolyte solution;
(4) housing a negative electrode provided with the negative electrode active material layer, a positive electrode provided with a positive electrode active material layer, and a non-aqueous electrolyte containing the alkyne sulfonic acid compound in a battery case;
(5) performing a charge treatment between the positive electrode and the negative electrode;
Is included. In addition, said (1)-(4) can also be grasped | ascertained also as a manufacturing method of the above non-aqueous-electrolyte secondary battery assemblies.

  According to such a production method, a low-resistance and high-quality (for example, high thermal stability) film derived from the alkynesulfonic acid compound can be suitably formed on the surface of the negative electrode active material. For this reason, for example, a nonaqueous electrolyte secondary battery capable of achieving both durability and input / output characteristics at a high level can be suitably manufactured. Further, when determining the addition amount of the alkyne sulfonic acid compound, the volume of voids in the negative electrode active material layer is used as an index, for example, when the design parameters such as the basis weight and density of the negative electrode active material layer are changed. However, it is possible to deal flexibly with such changes. In other words, the optimal addition amount can be determined more quickly and accurately by using such an index. Therefore, an optimal amount of the coating can be stably formed on the surface of the negative electrode active material as compared with the conventional index that defines the addition amount with respect to the non-aqueous electrolyte. This is also preferable from the viewpoint of productivity and workability.

  In a preferred embodiment, the non-aqueous electrolyte contains ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate as the non-aqueous solvent, and the proportion of the ethylene carbonate in the whole non-aqueous solvent is 20 volumes. % To 40% by volume or less. In another preferred embodiment, the negative electrode active material layer contains natural graphite as a negative electrode active material.

  The non-aqueous electrolyte secondary battery obtained by charging the assembly as described above or the non-aqueous electrolyte secondary battery manufactured by the above-described manufacturing method preferably exhibits the effect of adding an alkyne sulfonic acid compound. It is characterized by being able to exhibit high battery characteristics in a wide temperature range (for example, durability and input / output characteristics can be compatible at a high level). That is, the battery disclosed herein can exhibit high output characteristics even in a low temperature environment, and can hardly cause a decrease in battery capacity even when used for a long time in a high temperature environment. Therefore, taking advantage of this feature, it can be suitably used in applications that can be used in a high energy density, high output density, or a wide temperature range (for example, a vehicle drive power supply). In other words, as another aspect disclosed herein, a vehicle including the nonaqueous electrolyte secondary battery is provided. The battery mounted on the vehicle may be in the form of an assembled battery in which a plurality of the batteries are electrically connected to each other.

It is a perspective view which shows typically the external shape of the nonaqueous electrolyte secondary battery assembly which concerns on one Embodiment. It is a longitudinal cross-sectional view which follows the II-II line | wire in FIG. It is a schematic diagram which shows the structure of the wound electrode body which concerns on one Embodiment. It is a graph which shows the relationship between the addition amount (mass%) of the alkynesulfonic acid compound in a non-aqueous electrolyte, and the measurement result of IV resistance (mohm) in 25 degreeC. It is a graph which shows the relationship between the addition amount (mass%) of the alkynesulfonic acid compound in a non-aqueous electrolyte, and the measurement result of IV resistance (mohm) in -15 degreeC. It is a graph which shows the relationship between the addition amount (g / cm < ³ >) of an alkynesulfonic acid compound with respect to the volume of the space | gap in a negative electrode active material layer, and the measurement result of IV resistance (m (omega | ohm)) at -15 degreeC.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate. Matters necessary for the implementation of the present invention other than matters specifically mentioned in the present specification can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. In the following drawings, members / parts having the same action are described with the same reference numerals, and redundant descriptions may be omitted or simplified. Further, the dimensional relationship (length, width, thickness, etc.) in each drawing does not necessarily reflect the actual dimensional relationship.

≪Nonaqueous electrolyte secondary battery assembly≫
According to the present invention, a non-aqueous electrolyte secondary battery assembly is provided. Such an assembly includes a positive electrode provided with a positive electrode active material layer, a negative electrode provided with a negative electrode active material layer, and a non-aqueous electrolyte containing an alkyne sulfonic acid compound in a battery case. The non-aqueous electrolyte contains the alkyne sulfonic acid compound in an amount of 0.012 g or more and 0.023 g or less per 1 cm ³ of void volume in the negative electrode active material layer.

  Although not intended to be particularly limited, in the following, as a schematic configuration of the nonaqueous electrolyte secondary battery assembly according to an embodiment of the present invention, a flatly wound electrode body (wound electrode body) The present invention will be described in detail by taking, as an example, a non-aqueous electrolyte secondary battery assembly in which a non-aqueous electrolyte is accommodated in a flat rectangular (box-shaped) container (battery case).

1 and 2 show a schematic configuration of a nonaqueous electrolyte secondary battery assembly according to an embodiment of the present invention. FIG. 1 is a perspective view schematically showing the outer shape of a nonaqueous electrolyte secondary battery assembly 100. FIG. 2 is a longitudinal sectional view schematically showing a sectional structure taken along line II-II of the non-aqueous electrolyte secondary battery assembly 100 shown in FIG.
As shown in FIGS. 1 and 2, the nonaqueous electrolyte secondary battery assembly 100 includes a long positive electrode sheet 10 and a long negative electrode sheet 20 that are flattened via a long separator sheet 40. The electrode body (winding electrode body) 80 wound in the form of a battery is housed in a flat box-shaped battery case 50 together with a non-aqueous electrolyte (not shown).

≪Battery case 50≫
The battery case 50 includes a flat rectangular parallelepiped (box-shaped) battery case main body 52 having an open upper end, and a lid 54 that closes the opening. On the upper surface of the battery case 50 (that is, the lid 54), a positive terminal 70 for external connection that is electrically connected to the positive electrode of the wound electrode body 80 and a negative electrode that is electrically connected to the negative electrode of the wound electrode body 80. A terminal 72 is provided. The lid 54 is also provided with a safety valve 55 for discharging the gas generated inside the battery case 50 to the outside of the case 50, similarly to the battery case of the conventional nonaqueous electrolyte secondary battery.
Examples of the material of the battery case 50 include metal materials such as aluminum and steel; resin materials such as polyphenylene sulfide resin and polyimide resin. Among these, relatively light metals (for example, aluminum and aluminum alloys) can be preferably employed for the purpose of improving heat dissipation and increasing energy density. In addition, the shape of the case (outer shape of the container) is a rectangular parallelepiped shape here, for example, a circular shape (cylindrical shape, coin shape, button shape), hexahedral shape (rectangular shape, cubic shape), bag shape, and The shape etc. which processed and deformed them can be employ | adopted.

≪Winded electrode body 80≫
FIG. 3 is a schematic diagram showing the configuration of the wound electrode body 80 shown in FIG. As shown in FIG. 3, the wound electrode body 80 according to the present embodiment includes a long sheet-like positive electrode (positive electrode sheet) 10 and a long sheet-like negative electrode (negative electrode sheet) 20 before assembly. ing. The positive electrode sheet 10 includes a long positive electrode current collector 12 and a positive electrode active material layer 14 formed on at least one surface (typically both surfaces) along the longitudinal direction. The negative electrode sheet 20 includes a long negative electrode current collector 22 and a negative electrode active material layer 24 formed on at least one surface (typically both surfaces) along the longitudinal direction. Further, an insulating layer that prevents direct contact between the positive electrode active material layer 14 and the negative electrode active material layer 24 is disposed. Here, two long sheet-like separators 40 are used as the insulating layer.
Such a wound electrode body 80 is obtained by, for example, winding a laminated body in which the positive electrode sheet 10, the separator sheet 40, the negative electrode sheet 20, and the separator sheet 40 are stacked in this order in the longitudinal direction, It can be produced by forming into a flat shape by pressing and curling.

  In the width direction defined as the direction from one end of the wound electrode body 80 to the other end in the winding axis direction, the central portion is formed on the surface of the positive electrode current collector 12. A wound core portion is formed in which the positive electrode active material layer 14 and the negative electrode active material layer 24 formed on the surface of the negative electrode current collector 22 are overlapped and densely stacked. Further, at both ends of the wound electrode body 80 in the winding axis direction, the positive electrode active material layer non-formed portion of the positive electrode sheet 10 and the negative electrode active material layer non-formed portion of the negative electrode sheet 20 are respectively outward from the wound core portion. It sticks out. A positive electrode current collector plate is attached to the positive electrode side protruding portion, and a negative electrode current collector plate is attached to the negative electrode side protruding portion, respectively. The positive electrode terminal 70 (FIG. 2) and the negative electrode terminal 72 (FIG. 2) are electrically connected to each other. It is connected to the.

≪Positive electrode sheet 10≫
The positive electrode sheet 10 includes a positive electrode current collector 12 and a positive electrode active material layer 14 including at least a positive electrode active material formed on the positive electrode current collector.
As the positive electrode current collector 12, a conductive member made of a metal having good conductivity (for example, aluminum, nickel, titanium, stainless steel, etc.) can be suitably employed.

<Positive electrode active material layer 14>
The positive electrode active material layer 14 includes at least a positive electrode active material. As the positive electrode active material, one or more of various materials known to be usable as a positive electrode active material for a non-aqueous electrolyte secondary battery can be used without any particular limitation. Preferable examples include layered and spinel-based lithium composite metal oxides (for example, LiNiO ₂ , LiCoO ₂ , LiFeO ₂ , LiMn ₂ O ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiCrMnO ₄ , LiFePO _4, etc. ). Among them, lithium nickel cobalt manganese composite oxide (for example, LiNi _1/3 Co) having a layered structure (typically a layered rock salt structure belonging to a hexagonal system) containing Li, Ni, Co, and Mn as constituent elements. _1/3 Mn _1/3 O ₂ ) is preferable because it is excellent in thermal stability and can realize a higher energy density than other compounds.

  Here, the lithium nickel cobalt manganese composite oxide is an oxide containing only Li, Ni, Co and Mn as constituent metal elements, and at least one other metal element in addition to Li, Ni, Co and Mn ( That is, it is meant to include oxides containing transition metal elements and / or typical metal elements other than Li, Ni, Co and Mn. Such metal elements include magnesium (Mg), calcium (Ca), strontium (Sr), titanium (Ti), zirconium (Zr), vanadium (V), niobium (Nb), chromium (Cr), molybdenum (Mo), Tungsten (W), iron (Fe), rhodium (Rh), palladium (Pb), platinum (Pt), copper (Cu), zinc (Zn), boron (B), aluminum (Al), gallium (Ga), It may be one or more elements of indium (In), tin (Sn), lanthanum (La), and cerium (Ce). The addition amount (blending amount) of these metal elements is not particularly limited, but is usually 0.01% by mass to 5% by mass (for example, 0.05% by mass to 2% by mass, typically 0.1% by mass to 0% by mass). 8 mass%). By setting the amount within the above range, excellent battery characteristics (for example, high energy density) can be realized.

  For the positive electrode active material layer 14, in addition to the positive electrode active material, one or more materials that can be used as components of the positive electrode active material layer 14 in a general non-aqueous electrolyte secondary battery are used as necessary. May be contained. Examples of such a material include a conductive material and a binder. As the conductive material, for example, carbon materials such as various carbon blacks (typically acetylene black and ketjen black), coke, activated carbon, graphite, carbon fiber, and carbon nanotube can be suitably used. As the binder, for example, a vinyl halide resin such as polyvinylidene fluoride (PVdF); a polyalkylene oxide such as polyethylene oxide (PEO); and the like can be preferably used.

  The proportion of the positive electrode active material in the entire positive electrode active material layer 14 is suitably about 60% by mass or more (typically 60% by mass to 99% by mass), and usually about 70% by mass to 95% by mass. % Is preferred. When a conductive material is used, the ratio of the conductive material in the entire positive electrode active material layer 14 can be, for example, approximately 2% by mass to 20% by mass, and usually approximately 3% by mass to 10% by mass. preferable. When using a binder, the ratio of the binder to the whole positive electrode active material layer 14 can be, for example, about 0.5 mass% to 10 mass%, and usually about 1 mass% to 5 mass%. preferable.

The mass (weight per unit area) of the positive electrode active material layer 14 provided per unit area of the positive electrode current collector 12 is 3 mg / cm ² or more per side of the positive electrode current collector 12 from the viewpoint of securing a sufficient battery capacity (for example, 5 mg / cm ² or more, typically 7 mg / cm ² or more). Further, from the viewpoint of securing battery characteristics (for example, input / output characteristics), it is set to 100 mg / cm ² or less (for example, 70 mg / cm ² or less, typically 50 mg / cm ² or less) per side of the positive electrode current collector. it can. In the configuration having the positive electrode active material layer 14 on both surfaces of the positive electrode current collector 12 as in this embodiment, the mass of the positive electrode active material layer 14 provided on each surface of the positive electrode current collector 12 is approximately the same. It is preferable that

The average thickness per one side of the positive electrode active material layer 14 is, for example, 20 μm or more (typically 50 μm or more), and can be 100 μm or less (typically 80 μm or less). Moreover, the density of the positive electrode active material layer 14 can be set to, for example, 1 g / cm ^{3 to} 4 g / cm ³ (for example, 1.5 g / cm ^{3 to} 3.5 g / cm ³ ). Moreover, the porosity of the positive electrode active material layer 14 can be set to, for example, 10 volume% to 50 volume% (typically 20 volume% to 40 volume%). When one or more of the above properties are satisfied, an appropriate void can be maintained in the positive electrode active material layer 14, and the nonaqueous electrolyte can be sufficiently infiltrated. Therefore, a wide reaction field with the charge carrier can be secured, and high input / output characteristics can be exhibited. Moreover, the electroconductivity in the positive electrode active material layer 14 can be kept favorable, and an increase in resistance can be suppressed. Furthermore, the mechanical strength (shape retention) of the positive electrode active material layer can be ensured, and good cycle characteristics can be exhibited.

Incidentally, the "porosity" as used herein, multiplied by 100 and divided by the apparent volume of the total pore volume (cm ³⁾ The active material layer obtained by the above measurement of a mercury porosimeter (cm ³⁾ Value. The apparent volume can be calculated by the product of the area (cm ² ) and the thickness (cm) in plan view.

  A method for producing such a positive electrode sheet 10 is not particularly limited. For example, first, a positive electrode active material and a material used as necessary are dispersed in an appropriate solvent, and a paste-like or slurry-like composition (positive electrode) Active material layer forming slurry) is prepared. Next, the prepared positive electrode active material layer forming slurry is applied to the elongated positive electrode current collector 12, and the solvent contained in the slurry is removed. Thereby, the positive electrode sheet 10 provided with the positive electrode active material layer 14 on the positive electrode current collector 12 can be produced. As the solvent, any of an aqueous solvent and an organic solvent can be used. For example, N-methyl-2-pyrrolidone (NMP) can be used. The operation of applying the slurry can be performed using an appropriate coating apparatus such as a gravure coater, a slit coater, a die coater, a comma coater, or a dip coater. Moreover, the removal of the solvent can also be performed by conventional general means (for example, heat drying or vacuum drying).

  In addition, the property (namely, average thickness, density, porosity) of the positive electrode active material layer 14 as described above is, for example, that the positive electrode sheet 10 is appropriately pressed after the positive electrode active material layer 14 is formed. Can be adjusted by. Various conventionally known press methods such as a roll press method and a flat plate press method can be employed for the press treatment. Further, such processing may be performed once or may be performed two or more times.

<< Negative Electrode Sheet 20 >>
The negative electrode sheet 20 includes a negative electrode current collector 22 and a negative electrode active material layer 24 including at least a negative electrode active material formed on the negative electrode current collector.
For the negative electrode current collector 22, a conductive material made of a metal having good conductivity (for example, copper, nickel, titanium, stainless steel, etc.) can be suitably used.

<Negative electrode active material layer 24>
The negative electrode active material layer 24 includes at least a negative electrode active material. As the negative electrode active material, one or more of various materials known to be usable as a negative electrode active material for a non-aqueous electrolyte secondary battery can be used without particular limitation. Preferable examples include carbon materials such as graphite (graphite), non-graphitizable carbon (hard carbon), graphitizable carbon (soft carbon), and carbon nanotubes. Especially, since it is excellent in electroconductivity and a high energy density is obtained, graphite-type materials (especially natural graphite), such as natural graphite and artificial graphite, can be used preferably. In general, in a battery equipped with a graphite-based material on the negative electrode, for example, when charging and discharging are repeated under severe conditions, the components (eg, non-aqueous solvent and supporting salt) contained in the non-aqueous electrolyte are gradually decomposed, resulting in energy density. Can be reduced. However, since the assembly disclosed here contains a suitable amount of the alkyne sulfonic acid compound, a coating derived from the alkyne sulfonic acid compound is necessary and sufficient on the surface of the negative electrode active material by the subsequent charging treatment. Can be formed. For this reason, according to the technique disclosed here, a non-aqueous electrolyte secondary battery having high durability can be realized.

Although the property of a negative electrode active material is not specifically limited, For example, it may be a particle form or a powder form. The average particle diameter of the particulate negative electrode active material can be, for example, 50 μm or less (typically 20 μm or less, for example, 1 μm to 20 μm, preferably 5 μm to 15 μm). The specific surface area is 1 m ² / g or more (typically 2.5 m ² / g or more, for example, 2.8 m ² / g or more), and 10 m ² / g or less (typically 3.5 m ² / G or less, for example 3.4 m ² / g or less). The negative electrode active material satisfying one or two of the above properties can ensure a wide reaction field of charge carriers even when a film is formed on the surface by subsequent charging treatment, and has high battery characteristics ( For example, high input / output characteristics) can be realized.

In the present specification, the “average particle size” means particles corresponding to 50% cumulative from the fine particle side in the volume-based particle size distribution measured by particle size distribution measurement based on a general laser diffraction / light scattering method. diameter _{(D 50} particle size, also called median diameter.) refers to. In this specification, “BET specific surface area (m ² / g)” means a gas adsorption amount measured by a gas adsorption method (fixed capacity adsorption method) using nitrogen (N ₂ ) gas as an adsorbate. The value calculated by analyzing by the BET method (for example, the BET 1-point method).

  In addition to the above negative electrode active material, the negative electrode active material layer 24 may include one or more materials that can be used as a constituent component of the negative electrode active material layer in a general non-aqueous electrolyte secondary battery as necessary. May be contained. Examples of such materials include binders and various additives. As the binder, for example, a polymer material such as styrene butadiene rubber (SBR), polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), or the like can be suitably used. In addition, various additives such as a thickener, a dispersant, and a conductive material can be used as appropriate. For example, carboxymethylcellulose (CMC) or methylcellulose (MC) can be suitably used as the thickener.

  The proportion of the negative electrode active material in the entire negative electrode active material layer 24 is suitably about 50% by mass or more, and is usually 90% by mass to 99% by mass (eg, 95% by mass to 99% by mass). Is preferred. When using a binder, the ratio of the binder to the whole negative electrode active material layer 24 can be, for example, about 1% by mass to 10% by mass, and usually about 1% by mass to 5% by mass is preferable. . When using a thickener, the ratio of the thickener to the whole negative electrode active material layer 24 can be made into about 1 mass%-10 mass%, for example, and usually is about 1 mass%-5 mass%. It is preferable to do.

Negative provided per unit area of the electrode current collector 22 negative electrode active material layer 24 mass (weight per unit area) is per side of the anode current collector ^{22 5mg / cm 2 ~20mg / cm} 2 ( typically 7 mg / cm ^{2 to} 15 mg / cm ² ). In the configuration having the negative electrode active material layer 24 on both surfaces of the negative electrode current collector 22 as in this embodiment, the mass of the negative electrode active material layer 24 provided on each surface of the negative electrode current collector 22 is approximately the same. It is preferable to do.

The porosity of the negative electrode active material layer 24 can be, for example, about 5% by volume to 50% by volume (preferably 35% by volume to 50% by volume). Moreover, the thickness per one side of the negative electrode active material layer 24 is, for example, 30 μm or more (typically 40 μm or more, preferably 50 μm or more), and can be 100 μm or less (preferably 80 μm or less). Moreover, the density of the negative electrode active material layer 24 can be set to, for example, about 0.5 g / cm ^{3 to} 2 g / cm ³ (preferably 1 g / cm ^{3 to} 1.5 g / cm ³ ). A high energy density can be achieved when one or more of the above properties are satisfied. Moreover, a moderate space | gap can be maintained in the negative electrode active material layer 24, and a non-aqueous electrolyte can fully be infiltrated. Therefore, a wide reaction field with the charge carrier can be secured, and high input / output characteristics can be exhibited. Furthermore, the interface with the non-aqueous electrolyte can be suitably maintained, and high durability (for example, cycle characteristics) can be exhibited.

  Although the method of producing such a negative electrode sheet 20 is not specifically limited, For example, it can carry out as follows. First, a negative electrode active material and a material used as necessary are dispersed in a suitable solvent to prepare a paste-like or slurry-like composition (a slurry for forming a negative electrode active material layer). Then, the prepared negative electrode active material layer forming slurry is applied to the elongated negative electrode current collector 22, and the solvent contained in the slurry is removed, whereby the negative electrode active material layer 24 is formed on the negative electrode current collector 22. The provided negative electrode sheet 20 can be produced. As the solvent, any of an aqueous solvent and an organic solvent can be used. For example, water can be used. The application of the slurry, removal of the solvent, press treatment, and the like can be performed in the same manner as in the case of the positive electrode sheet 10. Further, the porosity, thickness, and density of the negative electrode active material layer 24 can be adjusted by performing an appropriate press treatment, as in the case of the positive electrode active material layer 14 described above.

<< Separator sheet 40 >>
The separator sheet 40 interposed between the positive and negative electrode sheets 10 and 20 may be any sheet as long as it insulates the positive electrode active material layer 14 and the negative electrode active material layer 24 and has a nonaqueous electrolyte holding function and a shutdown function. . Preferable examples include a porous resin sheet (film) made of a resin such as polyethylene (PE), polypropylene (PP), polyester, cellulose, polyamide. Such a porous resin sheet may have a single-layer structure or a laminated structure of two or more layers (for example, a three-layer structure in which PP layers are laminated on both sides of a PE layer). The average thickness of the porous resin sheet can be, for example, about 10 μm to 40 μm. Further, the separator sheet 40 may be configured to include a porous heat-resistant layer on one side or both sides (typically, one side) of the porous resin sheet. Such a porous heat-resistant layer can be, for example, a layer containing an inorganic material (inorganic fillers such as alumina particles can be preferably employed) and a binder. Alternatively, it may be a layer containing insulating resin particles (for example, particles of polyethylene, polypropylene, etc.).

≪Nonaqueous electrolyte≫
The nonaqueous electrolytic solution contains at least a supporting salt and an alkynesulfonic acid compound in a nonaqueous solvent. The non-aqueous electrolyte exhibits a liquid state at normal temperature (for example, 25 ° C.), and in a preferred embodiment, the non-aqueous electrolyte always exhibits a liquid state under the battery use environment (for example, a temperature environment of −30 ° C. to 60 ° C.).

  As the non-aqueous solvent, organic solvents such as various carbonates, ethers, esters, nitriles, sulfones, and lactones used in the electrolyte of general non-aqueous electrolyte secondary batteries can be used. . Specific examples include ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). Such a non-aqueous solvent can be used individually by 1 type or in combination of 2 or more types as appropriate. In a preferred embodiment, a high dielectric constant solvent and a low viscosity solvent are mixed and used. By using such a mixed solvent, it is possible to achieve high electrical conductivity and use in a wide temperature range. Examples of the high dielectric constant solvent include EC, and examples of the low viscosity solvent include DMC and EMC. For example, one or more carbonates are included as the non-aqueous solvent, and the total volume of these carbonates is 60% by volume or more (more preferably 75% by volume or more, more preferably 90% by volume) of the total volume of the non-aqueous solvent. % Or more and may be substantially 100% by volume). Moreover, in another suitable one aspect | mode, ethylene carbonate accounts for 20 volume% or more and 40 volume% or less of the whole nonaqueous solvent.

The supporting salt is the same as that of a general non-aqueous electrolyte secondary battery as long as it contains a charge carrier (for example, lithium ion, sodium ion, magnesium ion, etc., lithium ion in a lithium ion secondary battery). Those can be appropriately selected and used. For example, when the charge carrier is lithium ion, lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li (CF ₃ SO ₂ ) ₂ N, LiCF ₃ SO ₃ are exemplified. Such a supporting salt can be used singly or in combination of two or more. LiPF ₆ may be mentioned as particularly preferred support salt. Moreover, it is preferable to prepare the non-aqueous electrolyte so that the concentration of the supporting salt is within a range of 0.7 mol / L to 1.3 mol / L.

The alkynesulfonic acid compound includes at least one sulfonyloxy group (R—S (═O) ₂ —O—) and a carbon skeleton having a triple bond. As the alkyne sulfonic acid compound, alkyne sulfonic acid and its derivatives can be used, and those prepared by a known method or those obtained by purchasing a commercially available product are not particularly limited, and one or two or more are used. Can do. As a preferred embodiment, there can be mentioned, for example, an alkynesulfonic acid compound having a triple bond at an intermediate position of the molecular structure represented by the above formula (I). By using such a compound, a good-quality film can be more stably formed on the surface of the negative electrode active material.

In the formula (I), R ¹ represents 1 to 12 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, or a pentyl group (preferably 1-6, more preferably 1-3) linear or branched alkyl groups; 3-6 carbon atoms (typically 6) such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, etc. A cycloalkyl group having 6 to 12 carbon atoms such as a phenyl group, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group, a propylphenyl group, a butylphenyl group, a naphthyl group, a methylnaphthyl group, a benzylphenyl group, or a biphenyl group. An aryl group; or a perfluoroalkyl group having 1 to 10 carbon atoms. In a preferred embodiment, R ¹ in the above formula (I) is an alkyl group having 1 carbon atom (methyl group). That is, the compound represented by the formula (I) preferably has a methanesulfonic acid group (CH ₃ —S (═O) ₂ —O—).

R ² , R ³ , R ⁴ and R ⁵ are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. In a preferred embodiment, R ^{2 to} R ⁵ in the above formula (I) are all hydrogen atoms. In such a case, reaction resistance in film formation can be reduced.

  Specific examples of such alkyne sulfonic acid compounds include 2-butyne-1,4-dioldi (methanesulfonate), 2-butyne-1,4-dioldi (ethanesulfonate), 3-hexyne-2,5- Diol di (methanesulfonate), 3-hexyne-2,5-dioldi (ethanesulfonate), 2,5-dimethyl-3-hexyne-2,5-dioldi (methanesulfonate), 2,5-dimethyl-3 -Hexin-2,5-diol di (ethanesulfonate) and the like. Among these, 2-butyne-1,4-dioldi (methanesulfonate) represented by the above formula (II) can be preferably used.

  Moreover, various salts are mentioned as a typical example of an alkynesulfonic acid derivative. Examples thereof include lithium salts, sodium salts, ammonium salts, and methyl esters of aliphatic sulfonic acids or aromatic sulfonic acids.

In a preferred embodiment, the alkynesulfonic acid compound has the highest reduction potential (vs.
Li / Li ⁺ ). For example, since the reduction potential of 2-butyne-1,4-dioldi (methanesulfonate) is about 2.25 V (vs. Li / Li ⁺ ), other components (typically Is a reduction potential of vinylene carbonate compound and non-aqueous solvent (described later) that is approximately equal to or lower than 2.25 V (vs. Li / Li ⁺ ) (typically 0.1 V or more, for example 0.3 V). It is preferably lower than that, particularly 0.5 V or lower. Thereby, the coating derived from an alkyne sulfonic acid compound can be suitably formed on the surface of the negative electrode active material.

In the present invention, the non-aqueous electrolytic solution contains an alkynesulfonic acid compound in an amount of 0.012 g or more and 0.023 g or less per 1 cm ³ of void volume in the negative electrode active material layer. The alkyne sulfonic acid compound contained in the nonaqueous electrolytic solution can be decomposed by a subsequent charging process (typically, an initial charging process), and can be bonded (attached) to the surface of the negative electrode active material as a high-quality film. Therefore, when the addition amount of the alkyne sulfonic acid compound is less than 0.012 g, the film formed on the surface of the negative electrode active material becomes thin, and the durability (storage characteristics and rapid charge / discharge characteristics) of the battery may be reduced. On the other hand, when the addition amount is more than 0.023 g, the film formed on the surface of the negative electrode active material becomes thick, and there is a possibility that the resistance accompanying charge / discharge increases. When the addition amount of the alkyne sulfonic acid compound is in the above range, a non-aqueous electrolyte secondary battery capable of exhibiting high battery characteristics (for example, input / output characteristics and durability) can be realized under a wide temperature environment. .

  Such a nonaqueous electrolytic solution can be typically prepared by dissolving a supporting salt and an alkynesulfonic acid compound in a nonaqueous solvent. Alternatively, for example, an alkyne sulfonic acid compound is directly added to and impregnated into the electrode body (typically, the negative electrode active material layer or the separator) as described above, and the electrode body and a nonaqueous solvent containing a supporting salt are added. The alkyne sulfonic acid compound can be eluted into the non-aqueous electrolyte by being housed in the battery case.

The amount of the alkyne sulfonic acid compound used for battery construction (in other words, the amount of the alkyne sulfonic acid compound supplied into the battery case) can be determined by, for example, ion exchange chromatography as described later. Quantifying the amount of SO ₃ ²⁻ and SO ₄ ²⁻ contained in the material layer; analyzing the non-aqueous electrolyte accumulated in the battery case by ion exchange chromatography into alkyne sulfonic acid compounds and their decomposition products It can be generally grasped by a method such as quantifying the resulting chemical species;

≪Nonaqueous electrolyte secondary battery≫
In the non-aqueous electrolyte secondary battery obtained by charging the non-aqueous electrolyte secondary battery assembly as described above, a suitable amount of a coating derived from the alkyne sulfonic acid compound is formed on the surface of the negative electrode active material. Yes. Such a film typically contains an S element-containing group (for example, a sulfonyl group or a sulfonyloxy group) and a charge carrier. More specifically, SO ₃ ²⁻ , SO ₄ ^{2− and the} like may be included. This stabilizes the interface between the negative electrode active material (typically a graphite material) and the non-aqueous electrolyte, and thus can suitably suppress the decomposition of the non-aqueous electrolyte in subsequent charging and discharging, High durability (for example, cycle characteristics and high temperature storage characteristics) can be exhibited. In addition, since the coating on the surface of the negative electrode active material is thin enough not to hinder the movement of charge carriers associated with charge / discharge, the increase in resistance associated with the formation of the coating is kept low. Therefore, high input / output characteristics can be realized in a wide range of temperature environments (particularly in a low temperature environment). Therefore, such a non-aqueous electrolyte secondary battery can achieve both durability (cycle characteristics) and input / output characteristics at a high level.

The amount of the coating derived from the alkyne sulfonic acid compound formed on the surface of the negative electrode active material can be measured, for example, by a general ion exchange chromatography technique. Specifically, first, the negative electrode active material layer taken out by disassembling the battery is immersed and washed in an appropriate solvent (for example, EMC), and then cut into an appropriate size to obtain a measurement sample. Next, by immersing the measurement sample in a 50% acetonitrile (CH ₃ CN) aqueous solution for a predetermined time (for example, about 1 to 30 minutes), the film component (sulfide ion) to be measured is placed in the solvent. Extract. This solution is subjected to IC measurement, and the amounts of SO ₃ ²⁻ and SO ₄ ²⁻ (μM) are quantified from the obtained results. Then, by summing up these values and dividing by the area (cm ² ) of the negative electrode active material layer subjected to the measurement, the coating amount (μM / cm ² ) derived from the alkyne sulfonic acid compound in the measurement sample is obtained. Can do. According to such analysis, for example, even a battery using a non-aqueous electrolyte containing S atoms as a supporting salt is distinguished from S atoms derived from the supporting salt, and alkynesulfonic acid compounds (for example, 2-butyne- The presence of a coating derived from 1,4-diol di (methanesulfonate) can be recognized.

  In addition, as a method for measuring the amount of the coating, the case where ion exchange chromatography is used is specifically shown above. However, the method is not limited to this. For example, a conventionally known inductively coupled plasma emission spectroscopy (ICP-AES: The coating amount can also be grasped by inductively coupled plasma-atomic emission spectroscopy (X-ray absorption fine structure) (XAFS).

≪Method for manufacturing non-aqueous electrolyte secondary battery≫
The nonaqueous electrolyte secondary battery as described above can be suitably manufactured by a manufacturing method including the following steps.
(1) Negative electrode preparation step: preparing a negative electrode.
(2) Volume calculation step: determining the volume (cm ³ ) of voids in the negative electrode active material layer.
(3) Electrolyte preparation step; preparing a non-aqueous electrolyte containing an alkyne sulfonic acid compound.
(4) Assembly construction step: housing the negative electrode, the positive electrode, and the non-aqueous electrolyte containing the alkyne sulfonic acid compound in a battery case.
(5) Charging process step: performing a charging process between the positive electrode and the negative electrode.
According to this manufacturing method, an optimum amount of the coating can be stably formed on the surface of the negative electrode active material. Hereinafter, each process is demonstrated in order.

<(1) Negative electrode preparation step>
First, a negative electrode is prepared. The negative electrode includes a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector. As such a negative electrode, those already described above can be used.

<(2) Volume calculation process>
Next, the void volume (cm ³ ) in the negative electrode active material layer is determined. The volume of the voids in the negative electrode active material layer is calculated as described above (that is, by subtracting the total volume of each constituent material from the apparent volume) or by measurement (for example, by a general mercury porosimeter). Can be obtained by measuring under the following conditions). In addition, when the battery components and parameters (for example, the properties of the negative electrode active material layer) are changed, in principle, this step is preferably performed. However, for example, when the components and the like are not changed, 2 This step can be omitted after the first time.

<(3) Electrolyte preparation step>
Next, a nonaqueous electrolytic solution containing an alkyne sulfonic acid compound is prepared. At that time, the non-aqueous electrolyte contains the alkyne sulfonic acid compound in an amount of 0.012 g or more and 0.023 g or less per 1 cm ³ of the void volume in the obtained negative electrode active material layer. When determining the addition amount of the alkyne sulfonic acid compound, by using the volume of voids in the negative electrode active material layer as an index, for example, when the design parameters such as the basis weight and density of the negative electrode active material layer are changed, Can flexibly deal with such changes. In other words, the optimum addition amount can be determined more quickly and accurately by using the index disclosed here. Note that, as described above, the nonaqueous electrolytic solution contains a nonaqueous solvent and a supporting salt in addition to the alkynesulfonic acid compound. As these, those already described above can be used.

<(4) Assembly construction process>
Next, the negative electrode, the positive electrode, and the non-aqueous electrolyte containing the alkyne sulfonic acid compound are accommodated in a battery case. As the positive electrode, those already described above can be used. Thereafter, a lid is attached to the opening of the battery case, and the case and the lid are joined together by welding or the like, whereby an assembly can be constructed.

<(5) Charging process>
Then, a charging process is performed between the positive electrode and the negative electrode. Thus, a suitable amount of a coating derived from the alkyne sulfonic acid compound can be formed on the surface of the negative electrode active material. Such charging treatment is typically performed such that the negative electrode potential (vs. Li / Li ⁺ ) is equal to or lower than the reduction potential of the alkyne sulfonic acid compound contained in the non-aqueous electrolyte. In a preferred embodiment, the charge treatment is carried out until it is 0.05 V or more (typically 0.1 V or more, such as 0.3 V or more, particularly 0.5 V) lower than the reduction potential of the compound contained in the electrolytic solution. I do. For example, the voltage between the positive and negative terminals (typically the highest voltage reached) in the charging process varies slightly depending on the type of alkyne sulfonic acid compound to be used, but may be about 3.95 V to 4.05 V. it can.

  The charging process may be performed by, for example, a method of charging with a constant current (CC charging) from the start of charging until the negative electrode potential reaches a predetermined value (or until the negative electrode terminal voltage reaches a predetermined value), After charging with a constant current until the predetermined potential (or voltage) is reached, charging may be performed with a constant voltage (CCCV charging). In a preferred aspect, the charging process is performed by a CCCV charging method. The charging rate in CC charging is not particularly limited, but if it is too low, the processing efficiency tends to decrease. On the other hand, if it is too high, the denseness of the formed film may be insufficient, or the positive electrode active material may be deteriorated. For this reason, it is preferable to set it as 0.1C-2C (typically 0.5C-1.5C, for example, 0.6C-1C), for example. As a result, it is possible to accurately form a film having a suitable denseness (that is, a low resistance and capable of sufficiently suppressing the reaction with the non-aqueous electrolyte) in a shorter time.

  In addition, the said charge process may be performed once, for example, can also be repeatedly performed twice or more on both sides of a discharge process process. Furthermore, other operations (for example, pressure load or ultrasonic irradiation) that can promote the reductive decomposition of the above compound can be used in combination as long as the battery characteristics are not adversely affected.

  Although the battery disclosed here can be used for various applications, the effect of adding an alkyne sulfonic acid compound is suitably exhibited, and high battery characteristics can be realized in a wider temperature range than before (for example, durability) And input / output characteristics at a high level). Therefore, taking advantage of such properties, for example, it can be suitably used as a driving power source mounted on a vehicle. The type of vehicle is not particularly limited, and examples include plug-in hybrid vehicles (PHV), hybrid vehicles (HV), electric vehicles (EV), electric trucks, motorbikes, electric assist bicycles, electric wheelchairs, electric railways, and the like. . Thus, according to the present invention, there is provided a vehicle equipped with any of the nonaqueous electrolyte secondary batteries disclosed herein, preferably as a power source. The non-aqueous electrolyte secondary battery provided in the vehicle may be in the form of an assembled battery in which a plurality are connected.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to the specific examples.

[Construction of non-aqueous electrolyte secondary battery]
First, LiNi _0.38 Co _0.32 Mn _0.30 O ₂ (LNCM) as a positive electrode active material, acetylene black (AB) as a conductive material, and polyvinylidene fluoride (PVdF) as a binder, The mixture was put into a kneader so that the mass ratio of the materials was LNCM: AB: PVdF = 90: 8: 2, and kneaded while adjusting the viscosity with N-methylpyrrolidone (NMP) to prepare a positive electrode active material slurry. The slurry is applied to both surfaces of an aluminum foil (positive electrode current collector) having a thickness of 15 μm and pressed after drying, whereby a positive electrode sheet having a positive electrode active material layer on the positive electrode current collector (total thickness: 170 μm, electrode Density: 3 g / cm ³ , length 4500 mm).

Next, natural graphite (C) as a negative electrode active material, styrene butadiene rubber (SBR) as a binder, and carboxymethyl cellulose (CMC) as a dispersant, the mass ratio of these materials is C: SBR: CMC = The mixture was put into a kneader so that the ratio was 98: 1: 1, and kneaded while adjusting the viscosity with ion-exchanged water to prepare a negative electrode active material slurry. The slurry is applied to both surfaces of a 10 μm-thick long copper foil (negative electrode current collector) and dried and then pressed, whereby a negative electrode sheet having a negative electrode active material layer on the negative electrode current collector (total thickness: 150 μm, electrode density: 1.18 g / cm ³ , length 4700 mm).

(Example 1)
The positive electrode sheet and the negative electrode sheet prepared above are used as a separator having two layers (here, polyethylene (PE) and polypropylene (PP) laminated on both sides and having a thickness of 20 μm). And wound into a flat shape to produce a wound electrode body. Next, the positive electrode terminal and the negative electrode terminal were attached to the lid of the battery case, and these terminals were welded to the positive electrode current collector and the negative electrode current collector exposed at the ends of the wound electrode body, respectively. The wound electrode body thus connected to the lid body was housed inside the battery case from the opening, and the opening and the lid were welded. And the non-aqueous electrolyte (5g) was inject | poured from the electrolyte solution injection hole provided in the cover body. As a non-aqueous electrolyte, a mixed solvent containing ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of EC: DMC: EMC = 30: 40: 30 is used as a supporting salt. In which LiPF ₆ was dissolved at a concentration of 1.1 mol / L was used. In this way, a lithium ion secondary battery (Example 1) having a theoretical capacity of 285 kWh / m ³ was constructed.

(Examples 2 to 6)
In this example, 2-butyne-1,4-dioldi (methanesulfonate) (hereinafter sometimes abbreviated as “BDMS”) as an alkynesulfonic acid compound was added to the non-aqueous electrolyte. Except for this, lithium ion secondary batteries (Examples 2 to 6) were constructed in the same manner as in Example 1 above. The amount of BDMS added was 0.125% by mass in Example 2, 0.25% by mass in Example 3, 0.375% by mass in Example 4, and 0.5% in Example 5 with respect to the entire nonaqueous electrolyte. % By mass, in Example 6, 0.75% by mass.

(Example 7, Example 13)
In this example, lithium ion secondary batteries (Examples 7 and 13) were constructed in the same manner as in Example 1 except that the amount of the non-aqueous electrolyte used was 8 g in Example 7 and 11 g in Example 13.

(Examples 8-12, Examples 14-18)
In this example, a lithium ion secondary battery (Examples 8 to 8) was prepared in the same manner as in Examples 2 to 6, except that the amount of the non-aqueous electrolyte used was 8 g in Examples 8 to 12 and 11 g in Examples 14 to 18. 12, 14-18) were constructed.

[Charging process (conditioning process)]
About the battery of Examples 1-18 constructed | assembled above, the charge process was performed. Specifically, in an environment of 25 ° C., after performing constant current charging (CC charging) with a constant current of 0.5 C until the voltage between the positive and negative terminals reaches 4.1 V, the current value becomes 0. 0. Constant voltage charging (CV charging) was performed until the temperature reached 02C. Thereby, a film was formed on the surface of the negative electrode active material.

[Measurement of initial capacity]
About the battery after the said aging process, the rated capacity was measured according to the following procedures 1-3 at the temperature of 25 degreeC and the voltage range of 3.0V to 4.1V.
(Procedure 1) After reaching 3.0 V by constant current discharge of 0.33 C, discharge by constant voltage discharge for 2 hours, and then rest for 10 minutes.
(Procedure 2) After reaching 4.1V by constant current charge of 0.33 C, charge at constant voltage until the current reaches 0.02 C, and then rest for 10 minutes.
(Procedure 3) After reaching 3.0 V by constant current discharge of 0.33 C, constant voltage discharge is performed until the current becomes 0.02 C, and then stopped for 10 minutes.
Then, the discharge capacity (CCCV discharge capacity) in the discharge from the constant current discharge to the constant voltage discharge in the procedure 3 was set as the initial capacity. All the batteries of Examples 1 to 18 were confirmed to have a theoretical capacity (285 kWh / m ³ ).

[Measurement of IV resistance (25 ° C)]
Next, at a temperature of 25 ° C., the batteries of Examples 1 to 18 were constant-current charged to a state where the SOC was 60% at a charging rate of 1 C, and then the potential was adjusted by performing constant-voltage charging for 2 hours. This battery was charged and discharged with a charge / discharge pattern (Nos. 2 to 14) shown in Table 1 below under a temperature environment of 25 ° C., and a CC for 10 seconds at a discharge rate of 0.33C, 1C, and 3C. The voltage after discharge was measured. Then, the slope of the primary approximation line of the current (I) -voltage (V) plot at this time was obtained as IV resistance (mΩ).

The results are shown in FIG. In FIG. 4, ◆ indicates the batteries of Examples 1 to 6 (batteries with a nonaqueous electrolyte addition amount of 5 g), and ■ indicates the batteries of Examples 7 to 12 (batteries with a nonaqueous electrolyte addition amount of 8 g). , Δ represents the batteries of Examples 13 to 18 (batteries with a non-aqueous electrolyte addition amount of 11 g), respectively.
As is clear from FIG. 4, in the temperature environment of 25 ° C., the IV resistance is suppressed to the lowest when the addition amount of the alkyne sulfonic acid compound is 0.125% by mass, regardless of the injection amount of the electrolytic solution. I found out that

[Measurement of IV resistance (-15 ° C)]
Next, the potential was adjusted by performing constant current charging at a temperature of 25 ° C. until the SOC reached 60% at a charging rate of 1 C, and then performing constant voltage charging for 1.5 hours. This battery was charged and discharged with a charge / discharge pattern (No. 2 to 50) shown in Table 2 below in a temperature environment of −15 ° C., and the IV resistance (mΩ) was obtained in the same manner as described above.

The results are shown in FIG. 5 and FIG. FIG. 5 is a graph showing the addition amount (% by mass) of the alkyne sulfonic acid compound in the nonaqueous electrolytic solution on the X axis and the measurement result of IV resistance (mΩ) at −15 ° C. on the Y axis. FIG. 6 shows the measurement result of IV resistance (mΩ) at −15 ° C. on the Y axis with the addition amount (g / cm ³ ) of the alkyne sulfonic acid compound relative to the void volume in the negative electrode active material layer on the X axis. It is the shown graph. The symbols in the figure are the same as those in FIG.
As shown in FIG. 5, in the environment of −15 ° C., the amount of BDMS added that minimizes the IV resistance was different depending on the amount of the non-aqueous electrolyte. For this reason, in order to determine the optimum addition amount, it was found that the optimum addition amount suitable for the use of each battery needs to be examined and adjusted each time.
On the other hand, as shown in FIG. 6, when the addition amount of the alkyne sulfonic acid compound is determined using the void volume in the negative electrode active material layer as an index, the addition of the alkyne sulfonic acid compound does not depend on the amount of the electrolytic solution. IV resistance was suppressed lowest when the amount was set to ^{0.012g / cm 3 ~0.023g / cm 3} . Therefore, it was shown that high battery characteristics (for example, input / output characteristics and durability) can be exhibited by setting the addition amount of the alkynesulfonic acid compound in the above range. Moreover, it was shown that the optimum addition amount of the alkyne sulfonic acid compound can be easily determined by using such an index even when the parameters such as the properties of the negative electrode active material layer are changed. This result shows the technical significance of the present invention.

  As mentioned above, although this invention was demonstrated in detail, the said embodiment and Example are only illustrations and what changed and changed the above-mentioned specific example is contained in the invention disclosed here.

10 Positive electrode sheet (positive electrode)
12 Positive electrode current collector 14 Positive electrode active material layer 20 Negative electrode sheet (negative electrode)
22 Negative electrode current collector 24 Negative electrode active material layer 40 Separator sheet (separator)
DESCRIPTION OF SYMBOLS 50 Battery case 52 Battery case main body 54 Cover body 55 Safety valve 70 Positive electrode terminal 72 Negative electrode terminal 80 Winding electrode body 100 Nonaqueous electrolyte secondary battery assembly

Claims (9)

A set of non-aqueous electrolyte secondary batteries in which a positive electrode having a positive electrode active material layer, a negative electrode having a negative electrode active material layer, and a non-aqueous electrolyte containing an alkyne sulfonic acid compound are contained in a battery case. Three-dimensional
The alkyne sulfonic acid compound is 2-butyne-1,4-diol di (methanesulfonate),
The non-aqueous electrolyte contains the 2-butyne-1,4-dioldi (methanesulfonate) in an amount of 0.012 g or more and 0.023 g or less per 1 cm ³ of void volume in the negative electrode active material layer. An assembly of a non-aqueous electrolyte secondary battery. The thickness of one side of the negative electrode active material layer is 30 μm or more and 100 μm or less,
The assembly according to claim 1, wherein the density of the negative electrode active material layer is 1 g / cm ³ or more and 1.5 g / cm ³ or less. The non-aqueous electrolyte contains, as a non-aqueous solvent, ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate, and
The assembly according to claim 1 or 2, wherein a ratio of the ethylene carbonate to the whole nonaqueous solvent is 20% by volume or more and 40% by volume or less. The assembly according to any one of claims 1 to 3 , wherein the negative electrode active material layer includes natural graphite. The non-aqueous-electrolyte secondary battery comprised with the assembly as described in any one of Claim 1 to 4 by which charge processing was carried out . An assembled battery in which a plurality of batteries are electrically connected to each other;
The assembled battery, wherein each of the batteries constituting the assembled battery is the nonaqueous electrolyte secondary battery according to claim 5 . A method of manufacturing a non-aqueous electrolyte secondary battery comprising:
Preparing a negative electrode with a negative electrode active material layer;
Determining the volume (cm ³ ) of voids in the negative electrode active material layer;
Preparing a non-aqueous electrolyte containing an alkyne sulfonic acid compound;
Here , 2-butyne-1,4-dioldi (methanesulfonate) is used as the alkynesulfonic acid compound, and the volume of voids in the obtained negative electrode active material layer is included in the non-aqueous electrolyte. Including 2-butyne-1,4-dioldi (methanesulfonate) in an amount of 0.012 g or more and 0.023 g or less per cm ³ ;
Housing the negative electrode with the negative electrode active material layer, the positive electrode with a positive electrode active material layer, and the non-aqueous electrolyte containing the alkyne sulfonic acid compound in a battery case; and
Performing a charge treatment between the positive electrode and the negative electrode;
A method for producing a non-aqueous electrolyte secondary battery. The manufacturing method according to claim 7 , wherein a negative electrode active material layer having a thickness of 30 μm or more and 100 μm or less and a density of 1 g / cm ³ or more and 1.5 g / cm ³ or less is used as the negative electrode. . The non-aqueous electrolyte contains ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate as a non-aqueous solvent, and
The manufacturing method of Claim 7 or 8 prepared so that the ratio which occupies for the said non-aqueous solvent of the said ethylene carbonate may be 20 volume% or more and 40 volume% or less.

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