JP2014120367A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a capacity retention rate of a nonaqueous electrolyte secondary battery in which methyl phenyl carbonate is added to a nonaqueous electrolyte.SOLUTION: A nonaqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode and a nonaqueous electrolyte. The negative electrode has a negative electrode active material having a specific surface area of 2.0-4.0 m/g. The nonaqueous electrolyte contains 1.0-3.0 pts.wt. of methyl phenyl carbonate per 100 pts.wt. of a solvent. The nonaqueous electrolyte preferably contains less than 1.5 pts.wt. of methyl phenyl carbonate per 100 pts.wt. of a solvent.

Description

  The present invention relates to a non-aqueous electrolyte secondary battery.

  One of the non-aqueous electrolyte secondary batteries is a lithium ion secondary battery. A lithium ion secondary battery is a secondary battery that can be charged and discharged by moving lithium ions in a non-aqueous electrolyte between a positive electrode and a negative electrode that occlude and release lithium ions. As described in Patent Document 1, a nonaqueous electrolyte secondary battery in which 0.5 to 5% by mass of methylphenyl carbonate (MPhC, MPC) is added to an electrolytic solution is known.

International Publication No. 2012/120579

  In the battery described in Patent Document 1, MPhC is added to the electrolyte as a gas generating additive. Such a non-aqueous electrolyte secondary battery has excellent storage characteristics and resistance to overcharge. However, the capacity maintenance rate after high temperature use is low particularly when used for driving a vehicle. This invention is made | formed in order to solve such a problem, and makes it a subject to improve the capacity | capacitance maintenance factor of the nonaqueous electrolyte secondary battery which added MPhC to the nonaqueous electrolyte.

The non-aqueous electrolyte secondary battery of the present invention includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, the negative electrode has a negative electrode active material having a specific surface area of 2.0 to 4.0 m ² / g, And 1.0 to 3.0 parts by weight of methylphenyl carbonate with respect to 100 parts by weight of the solvent. The non-aqueous electrolyte preferably contains less than 1.5 parts by weight of methylphenyl carbonate with respect to 100 parts by weight of the solvent. The negative electrode active material is preferably natural graphite having an amorphous coat.

The positive electrode preferably has a positive electrode active material made of a transition metal composite oxide containing manganese. The transition metal composite oxide is more preferably LiNi _x Co _y Mn _z O ₂ (0 ≦ x ≦ 2/3, 0 ≦ y ≦ 2/3, 1/3 ≦ z <1, x + y + z = 1). . The transition metal composite oxide is particularly preferably LiNi _1/3 Co _1/3 Mn _1/3 O ₂ . The nonaqueous electrolyte secondary battery of the present invention may not include a pressure-sensitive current interruption mechanism. The battery for driving a vehicle according to the present invention includes the nonaqueous electrolyte secondary battery.

  According to the present invention, the capacity retention rate of the nonaqueous electrolyte secondary battery in which MPhC is added to the nonaqueous electrolyte is improved.

It is a graph showing the relationship between the active material specific surface area in the presence of MPhC and the capacity retention rate after high temperature storage. It is a graph showing the relationship between the active material specific surface area in the absence of MPhC and the capacity retention rate after high temperature storage. It is a graph showing the relationship between the active material specific surface area in the presence of other additives and the capacity retention rate after high temperature storage. It is a graph showing the relationship between the addition amount of MPhC and the capacity retention after high-temperature storage. It is a graph showing the relationship between the addition amount of another additive and the capacity retention after high-temperature storage. It is a graph showing the relationship between an active material specific surface area and the capacity | capacitance maintenance factor after charging / discharging.

  A non-aqueous electrolyte secondary battery (hereinafter sometimes simply referred to as a battery) according to an embodiment of the present invention is a lithium ion secondary battery. The battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte.

<Positive electrode>
The positive electrode is manufactured by stacking a positive electrode mixture having a positive electrode active material, a conductive material, and a binder (binder) on a positive electrode current collector. The positive electrode active material contains a material capable of inserting and extracting lithium. As such a material, for example, lithium cobalt oxide (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), lithium nickelate (LiNiO ₂ ), or the like can be used. _{Moreover, LiCoO 2, LiMn 2 O 4} , the LiNiO ₂ obtained by mixing in any ratio, may be used transition metal composite oxide.

The transition metal composite oxide preferably contains manganese. The composition of the transition metal composite oxide is LiNi _x Co _y Mn _z O ₂ (0 ≦ x ≦ 2/3, 0 ≦ y ≦ 2/3, 1/3 ≦ z <1, x + y + z = 1). LiNi _1/3 Co _1/3 Mn _1/3 O ₂ is particularly preferable. The positive electrode active material having such a composition, characterized by containing Mn, is excellent in energy density and generated voltage. Further, as the conductive material, for example, carbon black such as acetylene black (AB) and ketjen black (registered trademark), and graphite (graphite) can be used.

  The positive electrode mixture may contain a dispersant. As the dispersant, for example, a polyvinyl acetal-based dispersant (binder-type dispersant) can be used. Examples of the polyvinyl acetal dispersant include polyvinyl butyral, polyvinyl formal, polyvinyl acetoacetal, polyvinyl benzal, polyvinyl phenyl acetal, and copolymers thereof.

  As the binder, for example, polyvinylidene fluoride (PVdF), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), or the like can be used. For the positive electrode current collector, a material made of aluminum or an alloy containing aluminum as a main component can be used.

  In producing the positive electrode according to this embodiment, first, a positive electrode active material, a conductive material, a dispersant, and a binder are kneaded to obtain a positive electrode mixture paste. It is preferable to use a solvent in order to adjust the solid content or viscosity of the positive electrode mixture paste. As the solvent, N-methyl-2-pyrrolidone (NMP) or the like can be suitably used. Next, for example, the kneaded positive electrode mixture paste is applied onto the positive electrode current collector and dried. Next, the positive electrode may be adjusted to a desired density by rolling. The size of the positive electrode can be arbitrarily selected according to the capacity of the battery to be manufactured. The battery capacity may be about 4 to 20 Ah.

<Negative electrode>
The negative electrode active material is preferably a material capable of occluding and releasing lithium, and particularly preferably a powdery carbon material made of graphite. The graphite is preferably natural graphite. The negative electrode active material having graphite can also have an amorphous coating on the surface of graphite.

  When graphite is used as the negative electrode active material, it can have a specific surface area by adjusting the particle diameter by a known method. When graphite having an amorphous coat is used, the specific surface area can be obtained by adjusting the coating amount. Further, both the particle diameter and the coating amount can be adjusted.

The negative electrode active material preferably has a specific surface area of 2.0 to 4.0 m ² / g. When the specific surface area of the negative electrode active material is in such a range, the capacity retention rate of the battery is specifically improved as compared with the case where the specific surface area is not in such a range. Such an effect will be described in detail in Examples.

The negative electrode active material having a desired specific surface area can be selected from, for example, the graphite or amorphous coated graphite by evaluating the specific surface area by a gas adsorption method. For example, it is possible to evaluate these graphites by measuring the amount of adsorption by the N ₂ adsorption method and calculating the specific surface area by the BET method. In the present embodiment and examples, the specific surface area represents the N ₂ adsorption BET specific surface area.

  Similarly to the positive electrode, the negative electrode is prepared by laminating a negative electrode mixture having a negative electrode active material, a dispersant (solvent), a thickener, and a binder on a negative electrode current collector. As the thickener, carboxymethyl cellulose Na salt (CMC) is preferable. As the binder, styrene butadiene rubber (SBR) is preferable.

  The above materials are kneaded to obtain a negative electrode mixture paste. A negative electrode can be produced by applying and drying the kneaded negative electrode mixture paste on the negative electrode current collector. As the negative electrode current collector, for example, copper, nickel, or an alloy thereof can be used. The magnitude | size of a negative electrode can be arbitrarily selected according to the capacity | capacitance of the above-mentioned battery.

<Nonaqueous electrolyte>
A non-aqueous electrolyte is a composition having a non-aqueous solvent containing a supporting salt. Here, the non-aqueous solvent is not particularly limited. For example, one or two or more materials selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and the like are used as non-aqueous solvents. Can be used as

  From the viewpoint of enhancing battery characteristics, it is preferable to use a ternary solvent solvent composed of EC, DMC and EMC, and it is preferable to use a solvent mixed at a volume ratio of EC / DMC / EMC = 30/40/30. A desired supporting salt is dissolved in such a solvent to obtain a non-aqueous electrolyte.

Examples of the supporting salt include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiI, and the like. One or two or more selected lithium compounds (lithium salts) can be used. From the viewpoint of improving battery characteristics, LiPF ₆ is preferably used.

  The nonaqueous electrolyte according to the present embodiment preferably contains methylphenyl carbonate (MPhC) as an additive and contains this. The nonaqueous electrolyte preferably contains 1.0 to 3.0 parts by weight of MPhC with respect to 100 parts by weight of the solvent. When the added amount of MPhC is within such a range, the capacity retention rate of the battery is specifically improved as compared with the case where the amount of MPhC is not within such range. Such an effect will be described in detail in Examples.

  The nonaqueous electrolyte may contain more than 1.5 parts by weight of MPhC with respect to 100 parts by weight of the solvent. The non-aqueous electrolyte may contain 2.0 to 3.0 parts by weight of MPhC with respect to 100 parts by weight of the solvent. The nonaqueous electrolyte may contain less than 1.5 parts by weight of MPhC with respect to 100 parts by weight of the solvent.

<Separator>
Moreover, the lithium ion secondary battery according to the present embodiment may include a separator. As a separator, a porous polymer film such as a porous polyethylene film (PE), a porous polypropylene film (PP), a porous polyolefin film, and a porous polyvinyl chloride film, or a lithium ion or ion conductive polymer electrolyte film Can be used alone or in combination.

<Battery assembly>
A positive electrode, a negative electrode, and a non-aqueous electrolyte produced as described above are assembled into a battery. After laminating with a separator interposed between the upper positive electrode and the negative electrode, the laminate may be wound flatly (wound electrode body). The wound electrode body is accommodated in a container having a shape that can accommodate the wound electrode body. A container is provided with the container main body by which the upper end was open | released, and the cover body which block | closes the opening part.

  As a material constituting the container, a metal material such as aluminum or steel can be used. Further, for example, a container formed by molding a resin material such as polyphenylene sulfide resin (PPS) or polyimide resin may be used. The shape of the container includes a cylindrical shape, but is not particularly limited. When mounted on an automobile, it may be a large cell.

  The lid corresponding to the upper surface of the container is provided with a positive electrode terminal electrically connected to the positive electrode of the wound electrode body and a negative electrode terminal electrically connected to the negative electrode of the wound electrode body. In addition, a non-aqueous electrolyte is accommodated inside the container.

<Other structural features>
The pressure-sensitive current interrupting mechanism (CID mechanism) interrupts current according to the gas generated by the reaction of the gas generating additive during overcharge. The pressure-sensitive current interruption mechanism stops charging of the lithium ion secondary battery when the pressure inside the lithium ion secondary battery exceeds a predetermined value due to the gas generated during overcharging.

  MPhC added to the nonaqueous electrolyte in the present embodiment may be added for the purpose of gas generation. However, in the present embodiment, the main effect of MPhC is an improvement in the capacity maintenance rate. For this reason, it is good also as what does not have a pressure-sensitive type electric current interruption mechanism. For example, a temperature-sensitive current interrupt mechanism may be provided instead of the pressure-sensitive current interrupt mechanism.

  In the present embodiment, the structure can be simplified, for example, by not providing the battery with a pressure-sensitive current interruption mechanism. MPhC does not contribute to the operation of the temperature-sensitive current interruption mechanism, but improves the capacity maintenance rate of the battery. For this reason, the robustness of the battery is improved by simplifying the structure and improving the capacity maintenance rate.

  In addition, in a battery having a pressure-sensitive current interruption mechanism, an additive that responds to overcharge more sensitively than MPhC may be considered. In such a case, even if MPhC is further added, the contribution of MPhC to the pressure increase is small. In this case, as disclosed in the present embodiment, MPhC may be added mainly for the purpose of improving the capacity retention rate.

<Description of effects>
Since the capacity maintenance rate of the battery is improved by the method of the present embodiment, the burden on other battery members can be reduced. In addition, impurities that affect the capacity retention rate and the like can be relaxed at a level that may be included in each step. By these effects, the choice of the material which can be used for a battery can be increased.

  Depending on the specific surface area and addition amount of the negative electrode active material, MPhC in the non-aqueous electrolyte may be reduced on the negative electrode before acting on the positive electrode, which may hinder the reaction on the positive electrode. is there. The method of the present embodiment overcomes the ease of deterioration of the positive electrode active material, which is the cause of a decrease in the capacity retention rate of the battery. That is, MPhC is adsorbed on the positive electrode active material, thereby forming a film on the positive electrode and preventing elution of the positive electrode metal such as Mn.

  The battery of this embodiment can be used as a drive power source or a vehicle drive battery by being mounted on a transport machine or vehicle such as an electric vehicle (EV) or a plug-in hybrid vehicle (PHV). Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

[Production of battery]
The batteries of Examples 1 to 8 and Comparative Examples 1 to 57 were small cells with a capacity of 4 Ah. The batteries of Examples 9 to 11 and Comparative Examples 58 to 70 were on-vehicle large cells with a capacity of about 20 Ah.

<Preparation of positive electrode>
When the total amount of the positive electrode mixture was 100% by weight, LiNi _1/3 Co _1/3 Mn _1/3 O ₂ was used as the positive electrode active material. A positive electrode active material and a binder (PVdF) were added to NMP (N-methyl-2-pyrrolidone) and mixed to prepare a positive electrode mixture paste. Thereafter, the positive electrode material mixture paste prepared as described above was applied onto a 15 μm-thick aluminum foil serving as a positive electrode current collector. After applying the positive electrode mixture paste, the density was adjusted by drying, rolling and the like.

<Production of negative electrode>
The negative electrode active material of each Example and each Comparative Example was obtained by applying an amorphous coating to natural graphite having a particle size of 18 to 23 μm. The amorphous coat was 2 parts by weight with respect to 100 parts by weight of natural graphite. Here, 2 parts by weight of amorphous coating means that the amount of amorphous material relative to the core material, specifically, the amount of amorphous material after firing is 2 parts by weight. For this reason, this notation does not indicate the amount of amorphous carbon used for forming the amorphous coat, so-called charging amount. Each negative electrode active material was obtained by measuring and measuring the specific surface area under the following measurement conditions.

Using the N ₂ adsorption method, the BET specific surface area of the negative electrode active material was measured as follows. As a sample, the negative electrode active material concerning the said Example and each comparative example was used. The sample was precisely weighed and then sealed in a test tube, and the BET specific surface area was measured by adsorption of nitrogen gas. The specific surface area was calculated by applying the BET theory. The specific surface area was calculated by analyzing a relative pressure region of about 0.05 to 0.3 in the BET plot according to the same theoretical formula.

The N ₂ adsorption BET specific surface areas of the negative electrode active materials of Examples 1 to 3 and 9 to 11 and Comparative Examples 1 to 29 and 58 to 70 in FIGS. The N ₂ adsorption BET specific surface areas of Examples 4 to 8 and Comparative Examples 30 to 35 in FIG. 4 described later were equivalent to those of Example 2. The N ₂ adsorption BET specific surface area of Comparative Examples 36 to 57 in FIG. 5 described later was equivalent to that of Comparative Example 15. About the capacity maintenance rate of the battery of each Example or the comparative example, the difference of the quantity might arise a little in the absolute value.

  The natural graphite powder, SBR (styrene butadiene rubber), and CMC (carboxymethyl cellulose) were kneaded with water so that the mass ratio of these materials was 98: 1: 1 to prepare a negative electrode mixture paste. . Thereafter, this negative electrode mixture paste was applied to a copper foil (negative electrode current collector) and dried. Finally, it was rolled with a rolling press to adjust the density. As the copper foil, one for a small cell and one for a vehicle-mounted large cell were used.

<Nonaqueous electrolyte>
As the non-aqueous electrolyte, a mixed solvent containing EC, DMC, and EMC at a volume ratio of 30:40:30 and containing LiPF ₆ as a supporting salt at a concentration of about 1M was used.

<Additives>
In Examples and specific comparative examples, 0.125 to 4.0 parts by weight (0.125 to 4.0% by weight) of the additive was added to the nonaqueous electrolyte with respect to 100 parts by weight of the mixed solvent. The additive was either MPhC, vinylene carbonate (VC), or propane sultone (PRS). 4 and 5 to be described later, the amounts of additives (weight%; hereinafter referred to as “addition amount”) in Examples 4 to 8 and Comparative Examples 30 to 57 and the mixed solvent weight are shown in Table 2.

  The additives and addition amounts of Examples 1 to 3 and Comparative Examples 1 to 5 in FIG. 1 described later and Examples 9 to 11 and Comparative Examples 58 to 62 in FIG. 6 were the same as those in Example 6. No additive was added to Comparative Examples 6 to 13 shown in FIG. 2 and Comparative Examples 63 to 70 shown in FIG. The additives and addition amounts of Comparative Examples 14 to 21 in FIG. 3 to be described later were equivalent to those of Comparative Example 40. The additives and addition amounts of Comparative Examples 12 to 29 in FIG. 3 described later were equivalent to those of Comparative Example 51.

<Battery assembly>
The positive electrode and the negative electrode produced by the above method were laminated via two separators. The laminate was wound and accommodated in a battery container together with a non-aqueous electrolyte, and the opening of the battery container was hermetically sealed. The battery container used was one for a small cell and one for a vehicle-mounted large cell. The capacity of the large cell was 20 Ah, and the capacity of the small cell was 4 Ah.

[Verification of effect]
<Durability against high temperature storage>
A battery charged to 90% SOC was subjected to a high temperature storage durability test in which the battery was stored at 60 ° C. for 30 days. Before and after the test, charge and discharge were performed as shown in Table 3 to measure the battery capacity, and the capacity retention rate (%) was determined as follows. Capacity maintenance rate (%) = (battery capacity after test / initial battery capacity) × 100.

(1) Evaluation of Influence of Specific Surface Area of Negative Electrode Active Material For the batteries of Examples 1 to 3 and Comparative Examples 1 to 5 to which 2% by weight of MPhC was added, the specific surface area of the negative electrode active material shown in Table 1 and the battery The relationship with the capacity maintenance rate is shown in FIG. As shown in FIG. 1, in the presence of MPhC, the capacity retention rate was higher as the specific surface area of the active material was smaller. In particular, in the batteries of Examples 1 to 3 in which the specific surface area is included in the range of 2.0 to 4.0 m ² / g, the capacity retention rate is significantly higher than that of the comparative example, which is 89% or more. . The improvement of the capacity retention rate was particularly remarkable when the specific surface area was in the range of 2.0 to 3.0 m ² / g.

FIG. 2 shows the relationship between the specific surface area of the negative electrode active material shown in Table 1 and the capacity retention rate of the battery for the batteries of Comparative Examples 6 to 13 to which MPhC was not added. As shown in FIG. 2, even in the absence of MPhC, the capacity retention rate was higher as the specific surface area of the active material was smaller. However, as seen in Examples 1 to 3, the capacity retention rate was not significantly increased by including the specific surface area in the range of 4.0 m ² / g or less. The capacity retention ratios of Comparative Examples 6 to 13 were 89% or less.

FIG. 3 shows the relationship between the specific surface area of the negative electrode active material shown in Table 1 and the capacity retention rate of the battery for the batteries of Comparative Examples 14 to 29 to which 1% by weight of VC or PRS was added. As FIG. 3 shows, the capacity maintenance rate was higher as the specific surface area of the active material was smaller even in the presence of VC or PRS. However, as seen in Examples 1 to 3, the capacity retention rate was not significantly increased by including the specific surface area in the range of 4.0 m ² / g or less.

  Therefore, the battery does not easily deteriorate even when the battery is stored for a long time at a high temperature by including the nonaqueous electrolyte containing MPhC and the negative electrode active material having a specific surface area in the above range. It was found that the capacity maintenance rate of the battery was greatly improved. It was shown that the effect has a change point of the capacity maintenance rate depending on the specific surface area. Moreover, it was shown that this effect is effective for the positive electrode which has manganese which is easy to elute.

(2) Evaluation of influence of additive amount of additive The amount of MPhC shown in Table 2 for the batteries of Examples 4 to 8 and Comparative Examples 30 to 35 having a negative electrode active material having a specific surface area of 3.0 m ² / g. FIG. 4 shows the relationship between the battery capacity retention rate and the battery capacity. As shown in FIG. 4, in the batteries of Examples 4 to 8 in which the addition amount is in the range of 1.0 to 3.0% by weight with respect to the mixed solvent, the capacity retention rate is significantly higher than that of the comparative example. It became 93% or more. The improvement of the capacity retention rate was particularly remarkable in the range of 1.0 to 1.5% by weight.

FIG. 5 shows the relationship between the addition amount of VC or PRS shown in Table 2 and the capacity retention rate of the battery for the batteries of Comparative Examples 36 to 57 including the negative electrode active material having a specific surface area of 3.0 m ² / g. . As shown in FIG. 5, when the addition amount is around 1.0% by weight with respect to the mixed solvent, the capacity retention rate tends to be high. However, as seen in Examples 4 to 8, the capacity retention rate was not significantly increased by the addition amount being included in the predetermined range.

From these things, when a battery is equipped with the nonaqueous electrolyte containing 1.0-3.0 weight% MPhC, and the negative electrode active material whose specific surface area is 2.0-4.0 m < ² > / g, it takes It was found that even when the battery was stored at a high temperature for a long period of time, the battery was not easily deteriorated, and the capacity maintenance rate of the battery was greatly improved. It was shown that this effect has a change point of the capacity maintenance rate depending on the amount of MPhC added. Moreover, it was shown that this effect is effective for the positive electrode which has manganese which is easy to elute.

  In addition, it is shown that the specific surface area of the negative electrode active material has the above-mentioned predetermined value, exhibits a synergistic effect with MPhC contained in the nonaqueous electrolyte at a predetermined ratio, and contributes to the improvement of the durability performance of the battery. It was. Moreover, such a synergistic effect was remarkably observed in MPhC, but not in other additives.

<Durability against repeated charge and discharge>
For the batteries of Examples 9 to 11 and Comparative Examples 58 to 70, which are large vehicle-mounted cells, a charge / discharge test simulating the operation of the vehicle driving battery in an automobile traveling environment was performed. After carrying out a charge / discharge pattern cycle corresponding to 20,000 Ah at 60 ° C., the capacity retention rate was measured by the above method.

The ratio of the negative electrode active materials shown in Table 1 for the large cells of Examples 9 to 11 and Comparative Examples 58 to 62 to which 2% by weight of MPhC was added and the large cells of Comparative Examples 63 to 70 to which MPhC was not added The relationship between the surface area and the capacity retention rate of the large cell is shown in FIG. As shown in FIG. 6, in the presence of MPhC, the capacity retention rate was higher as the specific surface area of the active material was smaller. In particular, in the large cells of Examples 9 to 11 having a specific surface area in the range of 2.0 to 4.0 m ² / g, the capacity retention rate is significantly higher than that of the comparative example, which is 90% or more. It was.

Even in the absence of MPhC, the smaller the specific surface area of the active material, the higher the capacity retention rate. However, the capacity retention rate was generally lower than when MPhC was present. Moreover, as seen in Examples 9 to 11, the capacity retention rate was not significantly increased by including the specific surface area within the range of 4.0 m ² / g or less. The capacity retention rate of the large cells of Comparative Examples 58 to 70 was 90% or less.

  Accordingly, the battery is easily deteriorated even when the battery is used for a long time in an automobile driving environment by including the non-aqueous electrolyte containing MPhC and the negative electrode active material having a specific surface area in the above range. It was found that the capacity maintenance rate of the battery was greatly improved.

  As described above, the present invention is not limited to the configurations of the above-described embodiments or examples, and various modifications, corrections, and combinations that can be made by those skilled in the art within the scope of the invention of the claims of the claims of the present application. Of course.

Claims (8)

A positive electrode, a negative electrode, and a non-aqueous electrolyte;
The negative electrode has a negative electrode active material having a specific surface area of 2.0 to 4.0 m ² / g,
The non-aqueous electrolyte contains 1.0 to 3.0 parts by weight of methylphenyl carbonate with respect to 100 parts by weight of a solvent.
Non-aqueous electrolyte secondary battery.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the nonaqueous electrolyte contains less than 1.5 parts by weight of methylphenyl carbonate with respect to 100 parts by weight of the solvent.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode active material is natural graphite having an amorphous coat.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the positive electrode has a positive electrode active material made of a transition metal composite oxide containing manganese. The transition metal composite oxide is LiNi _x Co _y Mn _z O ₂ (0 ≦ x ≦ 2/3, 0 ≦ y ≦ 2/3, 1/3 ≦ z <1, x + y + z = 1). The non-aqueous electrolyte secondary battery described in 1. The non-aqueous electrolyte secondary battery according to claim 5, wherein the transition metal composite oxide is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ .   The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte secondary battery is not provided with a pressure-sensitive current interruption mechanism.   A battery for driving a vehicle, comprising the nonaqueous electrolyte secondary battery according to claim 1.

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