JP4596763B2 - Non-aqueous solvent type secondary battery - Google Patents

Description

  The present invention relates to a non-aqueous solvent secondary battery, and more specifically, the first charge / discharge efficiency despite the use of copper for the negative electrode core and the inclusion of a cyclic acid anhydride in the non-aqueous solvent electrolyte. The present invention relates to a non-aqueous solvent type secondary battery having a large current.

  With the rapid spread of portable electronic devices, the required specifications for the batteries used for them are becoming stricter year by year, and in particular, small and thin, high capacity, excellent cycle characteristics, and stable performance are required. Yes. In the field of secondary batteries, lithium non-aqueous solvent secondary batteries, which have a higher energy density than other batteries, are attracting attention. The proportion of lithium non-aqueous solvent secondary batteries accounts for a significant increase in the secondary battery market. Is shown.

  This lithium non-aqueous solvent type secondary battery includes a negative electrode in which a negative electrode active material mixture is applied in a film form on both sides of a negative electrode core (current collector) made of an elongated sheet-like copper foil and the like, and an elongated sheet-like battery A separator made of a microporous polypropylene film or the like is placed between both sides of a positive electrode core made of aluminum foil or the like and coated with a positive electrode active material mixture in the form of a film, and the negative electrode and the positive electrode are insulated from each other by the separator. In the case of a rectangular battery, the wound electrode body is further crushed to form a flat shape, and a negative electrode lead and a positive electrode lead are respectively attached to predetermined portions of the negative electrode and the positive electrode. It has the structure which connected and accommodated in the exterior of a predetermined shape.

  The non-aqueous solvent used in such a non-aqueous solvent type secondary battery needs to have a high dielectric constant in order to ionize the electrolyte, and needs to have high ionic conductivity in a wide temperature range. Therefore, carbonates such as propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), diethyl carbonate (DEC), lactones such as γ-butyrolactone, etc., ethers, ketones, esters, etc. Organic solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC) are widely used. However, due to the low vapor pressure, the battery tends to swell when left at high temperatures. It had.

  On the other hand, a non-aqueous solvent containing PC or BC has a high vapor pressure and high oxidation potential, so that it is difficult to decompose, so that the amount of gas generated is small, and the battery is difficult to swell. Since it has a low freezing point, it has a feature of excellent low temperature characteristics.

  Negative electrodes using carbonaceous materials such as graphite and amorphous carbon as negative electrode materials are widely used because of their low cost and excellent cycle life, but non-water containing PC and BC. When a solvent-based electrolyte is used, the battery capacity is reduced due to reductive decomposition of PC or BC during charging. In particular, in high-capacity carbonaceous materials (natural graphite, artificial graphite) that have been graphitized, there has been a problem that PC or BC decomposes more violently and charging does not proceed well.

  Therefore, conventionally, in order to suppress the reductive decomposition of the organic solvent, various compounds are added to the non-aqueous solvent electrolyte so that the negative electrode active material does not directly react with the organic solvent. Technology for controlling the negative electrode surface coating (SEI: Solid Electrolyte Interface. Hereinafter referred to as “SEI surface coating”) is important. For example, in Patent Document 1 below, at least one selected from vinylene carbonate and derivatives thereof is added to the electrolyte solution of a non-aqueous solvent secondary battery, and these additives add the negative electrode to the negative electrode by the first charge. An SEI surface coating is formed on the negative electrode active material layer before insertion of lithium so as to function as a barrier that prevents insertion of solvent molecules around lithium ions.

  In addition, for the same purpose, the following Patent Document 2 includes a non-aqueous solvent electrolyte in which a vinyl ethylene carbonate compound is added as an additive, and the following Patent Document 3 includes a vinylene carbonate compound and a vinyl ethylene carbonate compound. In addition, the following Patent Document 4 contains vinyl ethylene carbonate, and further added at least one kind of vinylene carbonate, cyclic sulfonic acid or cyclic sulfate, and cyclic acid anhydride is also described in Patent Document 5 below. Is added with a cyclic acid anhydride, and the following Patent Document 6 discloses the addition of a cyclic acid anhydride and a vinyl ethylene carbonate compound.

  Among these, it is known that the cyclic acid anhydride is decomposed before the reductive decomposition of the solvent at the time of charging to form the SEI film, so that the decrease in battery capacity can be suppressed. However, the cyclic acid anhydride contains a trace amount of water present in the battery (for example, usually about 5 to 40 ppm of water in the organic electrolyte and about 100 to 300 ppm of the positive electrode and the negative electrode active material). It is extremely affected by water and is easily hydrolyzed to produce carboxylic acid. Copper is conventionally used as a negative electrode core for non-aqueous solvent secondary batteries. However, this carboxylic acid easily elutes into the electrolyte, and the dissolved copper adversely affects the electrode reaction. Therefore, there has been a problem that the discharge efficiency is particularly lowered.

JP 08-045545 A (claims, paragraphs [0009] to [0012], [0023] to [0036]) JP 2001-006729 A (claims, paragraphs [0006] to [0014]) JP 2002-324580 A (claims, paragraphs [0008] to [0009]) JP 2003-151623 A (claims, paragraphs [0008] to [0009], [0022] to [0031]) JP 2000-268859 A (claims, paragraphs [0007] to [0008]) JP 2002-352852 A (claims, paragraphs [0010] to [0013]) JP 11-045724 A (claims, paragraphs [0006] to [0007])

The inventor has conducted various studies on the formation mechanism of the SEI surface coating of the non-aqueous solvent electrolyte containing the cyclic acid anhydride, and as a result, Li ₂ O, Na ₂ O, K ₂ O, By dispersing at least one metal oxide selected from alkali metal oxides such as CaO and MgO and alkaline earth metal oxides, the problem due to the dissolved copper is solved and the initial charge / discharge efficiency is achieved. It has been found that can be significantly increased. In this case, the metal oxide may be dispersed in any of the nonaqueous solvent electrolyte, the positive electrode mixture, and the negative electrode mixture.

  The reason why such a result is obtained is not clear at present, and it is necessary to wait for further research. Probably carboxylic acid, which is a hydrolysis product of cyclic acid anhydride, reacts with the metal oxide. Suppresses the dissolution reaction of copper used as a negative electrode core to undergo intramolecular dehydration. At this time, the metal oxide reacts with carboxylic acid to form a hydroxide, but the battery has low solubility. It is presumed that the effect of the present invention appeared as a result without inhibiting the reaction.

  Therefore, the object of the present invention is a nonaqueous solvent secondary battery having high initial charge / discharge efficiency despite the use of copper for the negative electrode core and the inclusion of a cyclic acid anhydride in the nonaqueous solvent electrolyte. Is to provide.

The above object of the present invention can be achieved by the following configurations. That is, the invention of the nonaqueous solvent secondary battery according to claim 1 and claim 2 of the present application includes a positive electrode containing a positive electrode active material capable of reversibly inserting and extracting lithium in a positive electrode mixture, and a negative electrode mixture. Nonaqueous solvent system comprising a negative electrode active material capable of reversibly occluding and releasing lithium, copper as a negative electrode core, and a nonaqueous solvent electrolyte containing a cyclic acid anhydride In the secondary battery, at least one metal oxide selected from an alkali metal oxide and an alkaline earth metal oxide is dispersed in at least one of the nonaqueous electrolyte, the positive electrode mixture, and the negative electrode mixture, and a cyclic acid anhydride The content of the product is in the range of 0.01 to 10% by mass of the total electrolyte mass, and when the metal oxide is dispersed in the non-aqueous electrolyte, the content of the metal oxide is 0.00% relative to the total electrolyte mass. 001 to 3 mass%, and the metal oxide is mixed with the positive electrode mixture or When dispersed in the negative electrode mixture, the content of the metal oxide is characterized in that 0.01 to 2% by weight relative to the positive electrode mixture or negative electrode mixture mass.

  Examples of the non-aqueous solvent (organic solvent) that constitutes the non-aqueous solvent electrolyte include carbonates, lactones, ethers, esters, and the like. Two or more of these solvents can be used in combination. Among these, carbonates, lactones, ethers, ketones, esters and the like are preferable, and carbonates are more preferably used.

  Specific examples include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), γ-butyrolactone, γ-valerolactone. , Γ-dimethoxyethane, tetrahydrofuran, 1,4-dioxane, diethyl carbonate and the like, and EC and chain carbonate are preferably used from the viewpoint of improving the charge / discharge efficiency.

Examples of the electrolyte constituting the nonaqueous solvent electrolyte include lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium borofluoride (LiBF ₄ ), and lithium hexafluoroarsenate (LiAsF ₆ ). And lithium salts such as lithium trifluoromethylsulfonate (LiCF ₃ SO ₃ ) and lithium bistrifluoromethylsulfonylimide (LiN (CF ₃ SO ₂ ) ₂ ). Of these, LiPF ₆ and LiBF ₄ are preferably used, and the amount dissolved in the non-aqueous solvent is preferably 0.5 to 2.0 mol / l.

The positive electrode active material in the positive electrode mixture includes a lithium transition metal composite oxide represented by Li _x MO ₂ (where M is at least one of Co, Ni, and Mn), that is, LiCoO ₂ , LiNiO ₂ , LiNi _y Co _1-y O ₂ (y = 0.01 to 0.99), Li _0.5 MnO ₂ , LiMnO ₂ , LiCo _x Mn _y Ni _z O ₂ (x + y + z = 1) or the like is single or plural. Are used as a mixture.

  As the negative electrode active material in the negative electrode mixture, at least one selected from the group consisting of a carbonaceous material, a siliconaceous material, and a metal oxide capable of occluding and releasing lithium is used. A carbonaceous material that has been graphitized is particularly preferable because it has a high capacity and the effects of the present invention become more significant.

（ただし、ｎ＝０〜４の整数であり、Ｒ₁〜Ｒ₄は、同じであっても異なっていても良く、Ｈもしくはアルキル基、アルケニル基又はアリール基からなる炭素数１〜１２の有機基を示す。また、Ｒ₁〜Ｒ₄は互いに結合して環を形成していてもよい。）
The invention according to claim 3 of the present application is characterized in that, in the non-aqueous solvent secondary battery according to claim 1 or 2 , the cyclic acid anhydride is represented by the following chemical formula.

(However, n is an integer of 0 to 4, and R _{1 to} R ₄ may be the same or different, and are organic having 1 to 12 carbon atoms composed of H, an alkyl group, an alkenyl group, or an aryl group. And R _{1 to} R ₄ may be bonded to each other to form a ring.)

The invention according to claim 4 of the present application is the nonaqueous solvent secondary battery invention according to claim 3 , wherein the cyclic acid anhydride is maleic anhydride, phthalic anhydride, succinic anhydride, anhydrous Methylsuccinic anhydride, 2,2-dimethylsuccinic anhydride, glutaric anhydride, 1,2-cyclohexanedicarboxylic anhydride, cis-1,2,3,6-tetrahydrophthalic anhydride, cis-5-norbornene-endo-2 , 3-dicarboxylic acid, phenyl succinic anhydride, 2-phenyl glutaric anhydride, and nonenyl succinic anhydride.

The invention according to claim 5 of the present application is the non-aqueous solvent secondary battery according to claim 1 or 2 , wherein the content of the cyclic acid anhydride in the non-aqueous solvent electrolyte is 0.00. 0 you wherein a 5% by mass to 5% by mass or more.

  When the content of the cyclic acid anhydride is less than 0.01% by mass, the effect of adding the cyclic acid anhydride is not substantially recognized. This is not preferable because the electrolyte concentration is reduced by reducing the amount of the solution and the electrical conductivity of the non-aqueous solvent electrolyte is reduced. More preferably, the content of the cyclic acid anhydride is 0.05 to 5% by mass of the total electrolyte mass.

The invention according to claim 6 of the present application is the nonaqueous solvent secondary battery according to claim 1 or 2 , wherein the metal oxide is Li ₂ O, Na ₂ O, K ₂ O, CaO, It is at least one selected from MgO.

Rb ₂ O, Ce ₂ O, which are alkali metal oxides, and BeO, SrO, BaO, which are alkaline earth metal oxides, cannot be used as the metal oxide, but Rb ₂ O, Ce ₂ O, SrO and BaO are not preferable because the molecular weight is large and the amount used is too large to achieve a predetermined action and effect. Also, BeO is not preferable because it is toxic.

The invention according to claim 7 of the present application is the nonaqueous solvent secondary battery according to claim 1, wherein the content of the metal oxide dispersed in the nonaqueous electrolyte is based on the total electrolyte mass. it is a 0.0 0 5 to 0.5 mass%.

  If the content of the metal oxide to be dispersed in the non-aqueous electrolyte is less than 0.001% with respect to the electrolyte mass, the effect of addition does not appear. In addition to saturation, the content of the electrolyte solvent is reduced by that amount, and the ionic conductivity is reduced. More preferably, content of the said metal oxide disperse | distributed to the said nonaqueous electrolyte is 0.05-0.5 mass% with respect to electrolyte mass.

The invention according to claim 8 of the present application is the nonaqueous solvent secondary battery according to claim 2 , wherein the content of the metal oxide dispersed in the positive electrode mixture or the negative electrode mixture is a positive electrode mixture. it is a 0.0 0 5 to 0.5 mass% with respect to, or the negative electrode mixture mass.

  If the content of the metal oxide to be dispersed in the positive electrode mixture or the negative electrode mixture is small, the effect of addition does not appear, and even if added in excess of 2% by mass, the effect is not only saturated, Since the positive electrode active material or the negative electrode active material content is reduced by that amount, the electrode capacity is reduced, which is not preferable. Preferably, the content of the metal oxide dispersed in the positive electrode mixture or the negative electrode mixture is 0.05 to 0.5% by mass with respect to the positive electrode mixture or the negative electrode mixture.

The invention according to claim 9 of the present application is the non-aqueous solvent secondary battery according to claim 1 or 2 , wherein the negative electrode active material has a d-value of 0 (zero) on the lattice plane (002 plane) in X-ray diffraction. The carbonaceous material is 340 nm or less, and the non-aqueous solvent contains PC or BC. As the crystallization of the carbonaceous material proceeds, the d value of the lattice plane (002 plane) in X-ray diffraction becomes smaller, and natural graphite and artificial graphite that have been crystallized have the d value of 0.340 nm or less. The present invention can also be applied to the case where the negative electrode contains such a highly crystallized carbonaceous material. In this case, a high-capacity nonaqueous solvent secondary battery can be obtained.

The invention according to claim 10 of the present application is characterized in that, in the nonaqueous solvent secondary battery according to claim 1 or 2 , the nonaqueous solvent electrolyte is gelled. When gelled, the gas generated by the oxidative decomposition of the cyclic acid anhydride tends to stay between the positive and negative electrode plates, and the capacity reduction due to the reduction of the effective electrode plate area is significant, so the effect of the present invention is greatly exhibited. .

  In the gel electrolyte, examples of the polymer holding the electrolytic solution include polymers such as an alkylene oxide polymer and a fluorine polymer such as a polyvinylidene fluoride-hexafluoropropylene copolymer. A method of forming a gel electrolyte using such a polymer material can be obtained by immersing the electrolytic solution in a polymer such as polyethylene oxide, polypropylene oxide, or a cross-linked isocyanate of polyalkylene oxide.

  In addition, a method of subjecting an electrolytic solution containing a polymerizable gelling agent to a polymerization treatment such as ultraviolet curing or thermosetting, or a method of cooling a solution obtained by dissolving a polymer that forms a gel electrolyte at room temperature at a high temperature. Are also preferably used. When the polymerizable gelling agent-containing electrolyte is used, examples of the polymerizable gelling agent include those having an unsaturated double bond such as acryloyl group, methacryloyl group, vinyl group, allyl group, epoxy, oxetane, formal. And those having a cationically polymerizable cyclic ether group.

  Specifically, acrylic acid, methyl acrylate, ethyl acrylate, ethoxyethyl acrylate, methoxyethyl acrylate, ethoxyethoxyethyl acrylate, polyethylene glycol monoacrylate, ethoxyethyl methacrylate, ethoxyethyl methacrylate, polyethylene glycol monomethacrylate, N, N- Diethylaminoethyl acrylate, glycidyl acrylate, allyl acrylate, acrylonitrile, diethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, polyalkylene glycol diacrylate , Polyalkylene glycol dimethacrylate, trimethylolpropane alkoxylate triacrylate, pentaerythritol alkoxylate tetraacrylate, pentaerythritol alkoxylate tetraacrylate and other monomers having an unsaturated double bond, methyl methacrylate and (3-ethyl-3- Oxetanyl) methyl acrylate copolymer (molecular weight of about 400,000), cyclic ether group-containing compounds such as tetraethylene glycol bisoxetane, and the like.

A monomer having an unsaturated bond can be polymerized by heat, ultraviolet light, electron beam, or the like, but a polymerization initiator may be added to the electrolytic solution in order to effectively advance the reaction. Examples of the polymerization initiator include organic compounds such as benzoyl peroxide, t-butyl peroxycumene, lauroyl peroxide, di-2-ethylhexyl peroxydicarbonate, t-butyl peroxypivalate, and t-hexyl peroxyisopropyl monocarbonate. Peroxides can be used. In addition, the cyclic ether group-containing compound is polymerized by heat or charge / discharge due to Li ⁺ or a small amount of H ⁺ in the electrolytic solution.

  On the other hand, a method of cooling a polymer that forms a gel electrolyte at room temperature at a high temperature is dissolved in an electrolyte solution. As such a polymer, a gel is formed with respect to the electrolyte solution and is stable as a battery material. Anything may be used. For example, polymers having a ring such as polyvinyl pyridine and poly-N-vinyl pyrrolidone; acrylic derivative polymers such as polymethyl acrylate and polyethyl acrylate; fluororesins such as polyvinyl fluoride and polyvinylidene fluoride; polyacrylonitrile, poly CN group-containing polymers such as vinylidene cyanide; polyvinyl alcohol polymers such as polyvinyl acetate and polyvinyl alcohol; halogen-containing polymers such as polyvinyl chloride and polyvinylidene chloride. Moreover, it can be used even if it is a mixture with said polymer | macromolecule, a modified body, a derivative | guide_body, a random copolymer, a graft copolymer, a block copolymer etc. The mass average molecular weight of these polymers is usually in the range of 10,000 to 5,000,000. When the molecular weight is low, it is difficult to form a gel. If the molecular weight is high, the viscosity becomes too high and handling becomes difficult.

The invention according to claim 11 of the present application is the nonaqueous solvent secondary battery according to claim 10 , wherein the gelled nonaqueous solvent electrolyte comprises an organic peroxide as a polymerization initiator. It was produced by injecting a polymer precursor as described above into a gel in a battery.

  When a polymer precursor containing an organic peroxide as a polymerization initiator is injected into the battery and gelled in the battery, the decomposition of the organic peroxide is accelerated when copper ions are eluted from the copper core, The pot life near the copper core is shortened, and the degree of polymerization becomes non-uniform in the battery and the battery characteristics are lowered.According to the present invention, since dissolution of copper from the copper core is suppressed, The effect appears greatly.

The invention according to claim 12 of the present application is the nonaqueous solvent secondary battery according to claim 10 , wherein the gelled nonaqueous solvent electrolyte is a polymer having a cyclic ether as a polymerization group. It is produced by injecting a precursor and allowing it to gel in a battery.

  When a polymer precursor having a cyclic ether as a polymerization group is injected into a battery and gelled in the battery, the polymerization reaction is accelerated by the carboxylic acid generated by hydrolysis of the cyclic acid anhydride, thereby reducing the pot life. As a result of difficulty in control, impregnation of the electrode plate with the gel nonaqueous solvent electrolyte tends to be insufficient, but according to the present invention, the carboxylic acid generated by hydrolysis of the cyclic acid anhydride is added. Since it reacts immediately with the metal oxide being subjected to intramolecular dehydration, it is particularly effective. In addition, when the pot life in the battery becomes non-uniform, a portion with a large amount of gel electrolyte and a portion with a small amount of gel electrolyte appear in the battery. Since it can suppress that such pot life becomes non-uniform | heterogenous, especially when a thin outer layer like a laminate exterior is used, an effect appears notably.

In addition, the invention according to claim 13 of the present application is the non-aqueous solvent secondary battery according to any one of claims 10 to 12 , wherein the electrolyte in the gelled non-aqueous solvent electrolyte The content of is not less than 50% by mass and not more than 99.5% by mass with respect to the total amount of the gelled non-aqueous solvent electrolyte, and the invention according to claim 14 is the above-mentioned claim. 13. The nonaqueous solvent secondary battery according to 13 , wherein the content of the electrolyte in the gelled nonaqueous solvent electrolyte is 75 with respect to the total amount of the gelled nonaqueous solvent electrolyte. It is characterized by being from 9% to 99.5% by mass.

  If the content of the electrolytic solution in the gelled non-aqueous solvent based electrolyte is too small, less than 50% by mass, the ionic conductivity is lowered and the high-load discharge efficiency is deteriorated. More preferably, it is 75 mass% or more with respect to the total amount of the gel electrolyte. Furthermore, when the content of the electrolytic solution exceeds 99.5% by mass, it is difficult to hold the electrolytic solution, and liquid leakage and leakage are likely to occur, and the gelled nonaqueous solvent electrolytic solution machine Strength cannot be obtained.

The invention according to claim 15 of the present application is characterized in that the nonaqueous solvent secondary battery according to claim 1 further includes a laminate outer package. According to the non-aqueous solvent secondary battery having such a configuration, the mass of the outer casing can be reduced and the thickness can be reduced, so that a small and lightweight non-aqueous solvent secondary battery can be obtained.

  The present invention includes a positive electrode containing a positive electrode active material capable of reversibly occluding and releasing lithium in a positive electrode mixture, and a negative electrode core comprising a negative electrode active material capable of reversibly occluding and releasing lithium in a negative electrode mixture. In a non-aqueous solvent secondary battery comprising a negative electrode using copper as a body and a non-aqueous solvent electrolyte containing a cyclic acid anhydride, at least one of the non-aqueous electrolyte, the positive electrode mixture, and the negative electrode mixture In addition, since at least one metal oxide selected from alkali metal oxides and alkaline earth metal oxides is dispersed, a stable SEI film can be obtained, and as described in detail below, the initial charge / discharge efficiency is improved. A remarkably improved nonaqueous solvent secondary battery is obtained.

  BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the best mode for carrying out the present invention will be described in detail using examples and comparative examples. First, a specific method for producing a nonaqueous solvent secondary battery common to the examples and comparative examples will be described. Will be described.

<Preparation of positive electrode plate>
A positive electrode active material made of LiCoO _{2 is} a carbon-based conductive agent (for example, 5% by mass) such as acetylene black and graphite, and a binder (for example, 3% by mass) made of polyvinylidene fluoride (PVdF) is N-methyl. A material dissolved in an organic solvent composed of pyrrolidone is mixed to obtain an active material slurry or an active material paste. When a metal oxide such as an alkali metal oxide and an alkaline earth metal oxide is added to the positive electrode mixture, it is prepared by dispersing in a slurry.

  These active material slurries or active material pastes use a die coater, doctor blade, etc. in the case of slurry, and in the case of paste, a positive electrode core (for example, an aluminum foil or aluminum mesh having a thickness of 15 μm) by a roller coating method or the like. A positive electrode plate coated with an active material layer is formed by uniformly applying to both sides. Thereafter, the positive electrode plate coated with the active material layer is passed through a drier to remove the organic solvent necessary for the preparation of the slurry or paste and dry it. After drying, this dry positive electrode plate is rolled by a roll press to obtain a positive electrode plate having a thickness of 0.15 mm.

<Preparation of negative electrode plate>
Dissolved in a negative electrode active material made of natural graphite (d (002) value = 0.335 nm), a binder (for example, 3% by mass) made of polyvinylidene fluoride (PVdF), etc., and an organic solvent made of N-methylpyrrolidone These are mixed to form a slurry or paste. When a metal oxide such as an alkali metal oxide and an alkaline earth metal oxide is added to the negative electrode mixture, it is prepared by dispersing in a slurry.

  These slurries or pastes are applied to the entire surface of the negative electrode core made of copper (for example, a copper foil having a thickness of 10 μm) using a die coater, a doctor blade or the like in the case of a slurry, or a roller coating method in the case of a paste. The negative electrode plate coated with the active material layer is formed uniformly. Thereafter, the negative electrode plate coated with the active material layer is passed through a drier to remove the organic solvent that was necessary when the slurry or paste was prepared, and then dried. After drying, the dried negative electrode plate is rolled by a roll press to obtain a negative electrode plate having a thickness of 0.14 mm.

<Production of electrode body>
The positive electrode plate and the negative electrode plate produced as described above are each provided with a microporous film (for example, a thickness of 0.020 mm) made of a polyolefin resin that is low in reactivity with an organic solvent and inexpensive, and each The center line in the width direction of the electrode plate is made to coincide and overlap. Then, it is wound by a winder. Thereafter, the outermost periphery is taped to form a spiral electrode body. The electrode bodies produced as described above are inserted into the exterior bodies made of aluminum laminate. Subsequently, the positive electrode current collection tab and the negative electrode current collection tab extended from the electrode body are welded with an exterior body.

<Preparation of electrolyte>
LiPF ₆ is dissolved in a solvent mixed at a mass ratio of EC / PC / EMC (20/10/70) to 1.0 M to prepare an electrolyte solution. The kind of cyclic acid anhydride is as having described in Table 1, and all addition amount is 1.5 mass% (vs. electrolyte mass). Further, the types and dispersion sites of metal oxides such as alkali metal oxides and alkaline earth metal oxides are as described in Table 1, and the addition amount is 0.3% by mass (vs. electrolyte mass, vs. electrode mixture mass).

  In the preparation of the gel electrolyte, a pregel is prepared by adding 8% by mass of tetraethylene glycol dimethacrylate as a monomer and 0.3% by mass of t-butyl peroxypivalate as a polymerization initiator to the above electrolyte. The types of cyclic acid anhydrides and metal oxides such as alkali metal oxides and alkaline earth metal oxides are as described in Table 1, and the addition amounts are 1.5% by mass and 0.3% by mass, respectively. %, And all are mass ratios relative to the electrolyte mass (electrolyte solution + monomer + polymerization initiator).

<Production of battery>
Next, a required amount of various nonaqueous solvent electrolytes were injected from the opening of the laminate outer package and sealed, and lithium ion nonaqueous solvent secondary batteries having a design capacity of 500 mAh for all of the examples and comparative examples were obtained. Produced. The gel electrolyte battery was prepared by pouring the required amount of pregel, sealing the opening, and polymerizing by heating at 70 ° C. for 3 hours to prepare a lithium polymer non-aqueous solvent secondary battery.

(Examples 1-10, Comparative Examples 1-4)
First,
(1) As nonaqueous solvent type secondary batteries of Examples 1, 3, and 5-8, MgO, which is a kind of alkaline earth metal oxide as a metal oxide, is dispersed in an electrolytic solution, and a cyclic acid anhydride is formed. 6 types of non-aqueous solvent type secondary batteries were manufactured by changing the type,
(2) As the nonaqueous solvent secondary battery of Example 2, Li ₂ O, which is a kind of alkali metal oxide, was dispersed in the electrolyte as the metal oxide, and succinic anhydride was used as the cyclic acid anhydride. Producing non-aqueous solvent type secondary battery,
(3) Lithium polymer nonaqueous solvent secondary battery using MgO as a metal oxide dispersed in a gel electrolyte and succinic anhydride as a cyclic acid anhydride as a nonaqueous solvent secondary battery of Example 4 Was made.

Also,
(4) As the nonaqueous solvent type secondary batteries of Examples 9 and 10, succinic anhydride is used as the cyclic acid anhydride, and MgO is used as the metal oxide in the positive electrode mixture (Example 9) or in the negative electrode mixture. Two types of non-aqueous solvent type secondary batteries were prepared by dispersing in (Example 10).

Similarly,
(5) As a nonaqueous solvent secondary battery of Comparative Examples 1 and 2, succinic anhydride is used as the cyclic acid anhydride, and Al ₂ O that is neither an alkali metal oxide nor an alkaline earth metal oxide as the metal oxide 2 non-aqueous solvent type secondary batteries were prepared by dispersing ₃ in the electrolyte (Comparative Example 1) or without dispersing the metal oxide (Comparative Example 2).
(6) As Comparative Examples 3 and 4, no cyclic acid anhydride was added, and MgO was dispersed as a metal oxide in the electrolyte (Comparative Example 3) or without dispersing the metal oxide (Comparative Example 4). Various types of nonaqueous solvent secondary batteries were produced.

<Charging / discharging conditions>
Various charge / discharge tests were performed under the following charge / discharge conditions for each of the nonaqueous solvent secondary batteries of Examples 1 to 10 and Comparative Examples 1 to 4 manufactured as described above.

<Measurement of initial charge / discharge efficiency>
First, each battery was charged at 25 ° C. with a constant current of 1 It (1C) = 500 mA, and after the battery voltage reached 4.2 V, it was charged with a constant voltage of 4.2 V for 3 hours. The amount of charge flowing at that time was determined as the initial charge capacity. Thereafter, discharging was performed at a constant current of 1 It until the battery voltage reached 2.75 V, the discharge capacity at this time was determined as the initial discharge capacity, and the initial charge and discharge efficiency was calculated based on the following equation. The results are shown in Table 1.
Initial charge / discharge efficiency (%) = (initial discharge capacity / initial charge capacity) × 100

From the results shown in Table 1, the following can be seen from the nonaqueous solvent secondary battery of Comparative Example 4 that does not contain both the cyclic acid anhydride and the metal oxide.
(A) In the non-aqueous solvent type secondary battery of Comparative Example 3 that contains only MgO in the electrolytic solution and does not contain the cyclic acid anhydride, the initial charge / discharge efficiency is similar to that of Comparative Example 4. ing.
(B) In the non-aqueous solvent type secondary battery of Comparative Example 2 which contains only cyclic acid anhydride in the electrolyte and does not contain metal oxides such as alkali metal oxides and alkaline earth metal oxides, the first charge / discharge The efficiency is slightly higher than that of Comparative Example 4.
(C) In the non-aqueous solvent secondary battery of Comparative Example 1 that contains both cyclic acid anhydride and Al ₂ O ₃ as the metal oxide in the electrolytic solution, the initial charge / discharge efficiency is higher than that of Comparative Example 4 It is slightly increased, and the same result as that of Comparative Example 2 is obtained.

on the other hand,
(D) In the non-aqueous solvent type secondary batteries of Examples 1, 3, and 5-8 including both cyclic acid anhydride and metal oxide MgO in the electrolytic solution, regardless of the type of cyclic acid anhydride, The initial charge / discharge efficiency is significantly higher than those of Comparative Examples 1 to 4.
(E) The non-aqueous solvent secondary battery of Example 2 containing both cyclic acid anhydride and Li ₂ O as the metal oxide in the electrolytic solution also has a first-time charge / discharge efficiency higher than that of Comparative Examples 1 to 4. The result is greatly increased, and almost the same results as those of Examples 1, 3, and 5 to 8 are obtained.
(F) In the nonaqueous solvent secondary battery of Example 4 in which both the cyclic acid anhydride and MgO as the metal oxide are included in the gelled nonaqueous solvent electrolyte, the initial charge / discharge efficiency is that of Comparative Examples 1 to 4. The results are much larger than those of Examples 1, 3, and 5 to 8, and almost the same results are obtained.
(G) In the nonaqueous solvent secondary batteries of Examples 9 and 10 in which the cyclic acid anhydride is included in the electrolytic solution and the metal oxide is dispersed in the positive electrode mixture or the negative electrode mixture, the first charge The discharge efficiency is significantly increased as compared with those of Comparative Examples 1 to 4, and almost the same results as those of Examples 1, 3, and 5 to 8 are obtained.

The following can be understood by summarizing the above results (a) to (g).
(A ′) Disperse both cyclic acid anhydride and metal oxides such as alkali metal oxides and alkaline earth metal oxides in the electrolyte solution, regardless of whether the electrolyte solution is liquid or gelled. Thus, good initial charge / discharge efficiency is achieved regardless of the type of cyclic acid anhydride.
(B ′) The metal oxide needs to be an alkali metal oxide or an alkaline earth metal oxide.
(C ′) Even if the metal oxide is dispersed in the positive electrode active material or the negative electrode active material, it has a predetermined effect.

  The effect of improving the initial charge / discharge efficiency by including a metal oxide such as an alkali metal oxide or an alkaline earth metal oxide with respect to the non-aqueous solvent electrolyte to which such a cyclic acid anhydride is added, It is seen from about 0.001% by mass with respect to the nonaqueous electrolyte mass, becomes very good at 0.05% by mass or more, and the effect tends to be saturated at about 0.5% by mass or more. Therefore, the content of the metal oxide is preferably 0.001% by mass or more, more preferably 0.05% by mass or more, based on the total electrolyte mass. Even if the content of the metal oxide is added up to about 3% by mass, a predetermined effect can be obtained. However, if the content exceeds 0.5% by mass, the electric conductivity of the non-aqueous solvent electrolyte starts to decrease, so the upper limit Is preferably 0.5% by mass.

  In addition, the effect of improving the initial charge / discharge efficiency due to the inclusion of a metal oxide such as an alkali metal oxide or an alkaline earth metal oxide in the positive electrode mixture or the negative electrode mixture is 0. It is seen from about 01% by mass, very good at 0.05% by mass or more, and the effect tends to be saturated at about 0.5% by mass or more. Therefore, the content of the metal oxide is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, based on the total electrolyte mass. Even if the content of the metal oxide is added up to about 2% by mass, the predetermined effect can be obtained. However, even if the content exceeds 0.5% by mass, the content of the positive electrode active material or the negative electrode active material is increased accordingly. Therefore, the upper limit is preferably set to 0.5% by mass.

In addition, in the above-mentioned Examples 1-10, although the example which added each cyclic acid anhydride and each metal oxide to one place one time was shown, even if it adds multiple each, it is also in multiple places It will be apparent to those skilled in the art that the same effect occurs even when added.

Claims (15)

The positive electrode mixture includes a positive electrode active material capable of reversibly occluding and releasing lithium, and the negative electrode mixture includes a negative electrode active material capable of reversibly occluding and releasing lithium, and copper as a negative electrode core. In the non-aqueous solvent secondary battery comprising the negative electrode used and a non-aqueous solvent electrolyte containing a cyclic acid anhydride,
At least one metal oxide selected from alkali metal oxides and alkaline earth metal oxide is dispersed in the nonaqueous electrolyte,
The content of the cyclic acid anhydride is in the range of 0.01 to 10% by mass of the total electrolyte mass,
Content of the said metal oxide disperse | distributed to the said nonaqueous electrolyte is 0.001-3 mass% with respect to the total electrolyte mass, The nonaqueous solvent type secondary battery characterized by the above-mentioned .   The positive electrode mixture includes a positive electrode active material capable of reversibly occluding and releasing lithium, and the negative electrode mixture includes a negative electrode active material capable of reversibly occluding and releasing lithium, and copper as a negative electrode core. In the non-aqueous solvent secondary battery comprising the negative electrode used and a non-aqueous solvent electrolyte containing a cyclic acid anhydride,
At least one metal oxide selected from alkali metal oxides and alkaline earth metal oxides is dispersed in at least one of the positive electrode mixture and the negative electrode mixture,
The content of the cyclic acid anhydride is in the range of 0.01 to 10% by mass of the total electrolyte mass,
Content of the said metal oxide disperse | distributed to the said positive mix or negative mix is 0.01-2 mass% with respect to a positive mix or negative mix mass.
A nonaqueous solvent secondary battery. The non-aqueous solvent secondary battery according to claim 1, wherein the cyclic acid anhydride is represented by the following chemical formula.

(Where n = 0 to 4 and R ₁ ~ R _Four These may be the same or different and each represents H or an organic group having 1 to 12 carbon atoms composed of an alkyl group, an alkenyl group, or an aryl group. R ₁ ~ R _Four May be bonded to each other to form a ring. ) The cyclic acid anhydride is maleic anhydride, phthalic anhydride, succinic anhydride, methyl succinic anhydride, 2,2-dimethyl succinic anhydride, glutaric anhydride, 1,2-cyclohexanedicarboxylic anhydride, cis-1, At least one selected from 2,3,6-tetrahydrophthalic acid, cis-5-norbornene-endo-2,3-dicarboxylic acid, phenyl succinic anhydride, 2-phenyl glutaric anhydride, and nonenyl succinic anhydride The non-aqueous solvent type secondary battery according to claim 3. 3. The nonaqueous solvent secondary battery according to claim 1, wherein the content of the cyclic acid anhydride is in the range of 0.05 to 5 mass% of the total electrolyte mass. The metal oxide _{is, Li 2 O, Na 2 O} , K 2 O, CaO, non-aqueous solvent secondary battery according to claim 1 or 2, characterized in that at least one selected from MgO. 2. The nonaqueous solvent-based secondary according to claim 1, wherein the content of the metal oxide dispersed in the nonaqueous electrolyte is 0.05 to 0.5 mass% with respect to the total electrolyte mass. battery. The content of the metal oxide dispersed in the positive electrode mixture or the negative electrode mixture is 0.05 to 0.5 mass% with respect to the positive electrode mixture or the negative electrode mixture mass. A nonaqueous solvent secondary battery according to 1. The negative electrode active material is a carbonaceous material having a d-value of 0.340 nm or less in a lattice plane (002 plane) in X-ray diffraction, and the non-aqueous solvent electrolyte contains propylene carbonate or butylene carbonate. The non-aqueous solvent secondary battery according to claim 1. The non-aqueous solvent secondary battery according to claim 1, wherein the non-aqueous solvent electrolyte is gelled. The gelled non-aqueous solvent electrolyte is prepared by injecting a polymer precursor using an organic peroxide as a polymerization initiator into a battery and allowing it to gel in the battery. The non-aqueous solvent secondary battery according to claim 10. The gelled nonaqueous solvent electrolyte is prepared by injecting a polymer precursor having a cyclic ether as a polymerization group into a battery and allowing the gel to gel in the battery. The non-aqueous solvent secondary battery according to claim 10. The content of the electrolytic solution in the gelled non-aqueous solvent electrolyte is 50% by mass or more and 99.5% by mass or less based on the total amount of the gelled non-aqueous solvent electrolyte. The nonaqueous solvent secondary battery according to any one of claims 10 to 12, The content of the electrolytic solution in the gelled nonaqueous solvent-based electrolyte solution is 75% by mass or more and 99.5% by mass or less based on the total amount of the gelated nonaqueous solvent electrolyte solution. The non-aqueous solvent secondary battery according to claim 13, wherein The nonaqueous solvent secondary battery according to claim 1, further comprising a laminate outer package.