JP4590680B2 - Non-aqueous electrolyte secondary battery and non-aqueous electrolyte used therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-aqueous electrolyte secondary battery and a non-aqueous electrolyte used therein. In detail, it is related with the improvement of the nonaqueous electrolyte secondary battery which has a lithium manganese oxide positive electrode using the specific nonaqueous electrolyte, and the nonaqueous electrolyte used for it.
The secondary battery of the present invention is excellent in cycle characteristics and storage characteristics even in a high temperature atmosphere.
[0002]
[Prior art]
With the recent reduction in weight and size of electrical products, development of lithium secondary batteries having a high energy density is in progress. In addition, with the expansion of the application field of lithium secondary batteries, improvement of battery characteristics is also demanded.
Secondary batteries that use metallic lithium as a negative electrode have been actively studied since long ago as batteries that can achieve higher capacities, but metallic lithium grows in a dendrite shape by repeated charge and discharge, and eventually becomes a positive electrode. Achieving a short circuit inside the battery is the biggest technical problem that impedes practical use.
[0003]
Therefore, a nonaqueous electrolyte secondary battery using a carbonaceous material capable of occluding and releasing lithium ions such as coke, artificial graphite, and natural graphite has been proposed for the negative electrode. In the non-aqueous electrolyte secondary battery, since lithium does not exist in a metallic state, dendrite formation is suppressed, and battery life and safety can be improved.
Lithium transition metal composite oxide materials such as lithium cobalt composite oxide, lithium nickel composite oxide, and lithium manganese composite oxide are used for the positive electrode, but they are resource-rich and inexpensive materials. A lithium-manganese composite oxide having a spinel structure has attracted attention.
[0004]
[Problems to be solved by the invention]
However, when this lithium manganese composite oxide is used for the positive electrode, the initial characteristics are almost satisfactory, but manganese ions in the positive electrode elute into the electrolyte due to the progress of charge / discharge cycles and long-term storage. As a result, it has been found that the battery characteristics deteriorate.
In particular, in a high temperature atmosphere, there is a problem that the deterioration of cycle characteristics and storage characteristics proceeds rapidly.
An object of the present invention is to provide a battery having excellent cycle characteristics and storage characteristics even in a high temperature atmosphere in a non-aqueous electrolyte secondary battery using a lithium manganese composite oxide as a positive electrode.
[0005]
[Means for Solving the Problems]
As a result of intensive studies in view of such circumstances, the present inventors are able to occlude and release lithium ions, and a positive electrode mainly composed of a lithium manganese composite oxide capable of inserting and extracting lithium ions. In a non-aqueous electrolyte secondary battery comprising at least a negative electrode mainly composed of a carbon material and an electrolyte obtained by dissolving a lithium salt in a mixed non-aqueous solvent containing at least a cyclic carbonate and a chain carbonate, Has been found to be able to improve cycle characteristics and storage characteristics even in a high temperature atmosphere by limiting the total amount of the carbonate in the mixed non-aqueous solvent containing the specific compound, and completed the present invention. It came to do.
[0006]
That is, the gist of the present invention is as follows.
1. A positive electrode mainly composed of a lithium manganese composite oxide having a spinel structure capable of occluding and releasing lithium ions, a negative electrode mainly comprising a carbon material capable of occluding and releasing lithium ions, and a ring In a non-aqueous electrolyte secondary battery comprising at least an electrolyte obtained by dissolving a lithium salt in a mixed non-aqueous solvent containing at least a carbonate and a chain carbonate, the electrolyte is succinic anhydride, glutaric anhydride, citraconic anhydride Acid, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6 Tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phenylco Click acid anhydride, 2-phenyl is selected from glutaric anhydride group consisting of compounds containing at least one cyclic acid anhydride, the ratio of cyclic acid anhydride to the total amount of the mixed nonaqueous solvent and a cyclic acid anhydride A non-aqueous electrolyte secondary battery, characterized in that it is 0.01 to 10% by weight, and 95% by weight or more of the mixed non-aqueous solvent is a cyclic carbonate and a chain carbonate,
[0007]
2. At least a positive electrode mainly composed of a lithium manganese composite oxide having a spinel structure capable of occluding and releasing lithium ions and a negative electrode mainly comprising a carbon material capable of occluding and releasing lithium ions. A non-aqueous electrolyte for a non-aqueous electrolyte secondary battery, wherein the non-aqueous electrolyte is obtained by dissolving a lithium salt in a mixed solvent containing at least a cyclic carbonate and a chain carbonate, and succinic anhydride, Glutaric anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3 , 4,5,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, Enirukohaku acid anhydride, 2-phenyl is selected from glutaric anhydride group consisting of compounds containing at least one cyclic acid anhydride, the ratio of cyclic acid anhydride to the total amount of the mixed nonaqueous solvent and a cyclic acid anhydride The nonaqueous electrolytic solution is characterized by being 0.01 to 10% by weight , and further 95% by weight or more of the mixed nonaqueous solvent is a cyclic carbonate and a chain carbonate.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The non-aqueous electrolyte secondary battery of the present invention has a positive electrode mainly composed of a lithium manganese composite oxide capable of occluding and releasing lithium ions, and a carbon material capable of occluding and releasing lithium ions as a main component. And a mixed non-aqueous solvent comprising 95% by weight or more of a cyclic carbonate and a chain carbonate in a lithium salt and a total amount of the solvent and the cyclic acid anhydride of 0.01 to 10% by weight of the cyclic acid anhydride At least from a non-aqueous electrolyte solution.
[0009]
The mixed nonaqueous solvent of the electrolytic solution contains 95% by weight or more of cyclic carbonate and chain carbonate, and preferably contains 20% by weight or more of cyclic carbonate and chain carbonate, respectively.
[0010]
The cyclic carbonate used for the mixed non-aqueous solvent is not particularly limited, but alkylene carbonate and alkenylene carbonate are preferable. In particular, alkylene carbonates having 2 to 4 carbon atoms in the alkylene group are preferred. Specific examples of such cyclic carbonates include, for example, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, vinyl ethylene carbonate, etc. Among them, ethylene carbonate and propylene carbonate are preferable.
About these alkylene groups or alkenylene groups, you may have a substituent within the range which does not inhibit the intended effect of this invention too much.
[0011]
The chain carbonate used for the mixed non-aqueous solvent is not particularly limited, but is preferably an alkyl carbonate, and particularly preferably an alkyl carbonate having 1 to 4 carbon atoms in the alkyl group. Specific examples of such alkyl carbonates include dimethyl carbonate, diethyl carbonate, di-n-propyl carbonate, ethyl methyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, etc. Dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate are preferred. About the alkyl group of these carbonates, you may have a substituent in the range which does not inhibit the intended effect of this invention too much.
[0012]
The combination of a cyclic carbonate and a chain carbonate is not particularly limited, but a combination of an alkylene carbonate having 2 to 4 carbon atoms in an alkylene group and a dialkyl carbonate having 1 to 4 carbon atoms in an alkyl group. Combination is preferred. Specific examples thereof include a combination of ethylene carbonate and / or propylene carbonate and at least one selected from dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
[0013]
If desired, the mixed non-aqueous solvent may contain a solvent other than the cyclic carbonate and the chain carbonate, but the amount thereof is 5% by weight or less.
Solvents other than carbonate include cyclic esters such as γ-butyrolactone and γ-valerolactone, chain esters such as methyl acetate and methyl propionate, sulfolane, diethyl sulfone, ethylene sulfite, dimethyl sulfite, diethyl sulfite, Examples thereof include sulfur-containing organic solvents such as propane sultone, and phosphorus-containing organic solvents such as trimethyl phosphate and triethyl phosphate. Two or more of these solvents may be mixed and used.
[0014]
The electrolytic solution used in the present invention contains a cyclic acid anhydride. The kind of the cyclic acid anhydride used in the present invention is not particularly limited as long as it is a compound having an acid anhydride structure in a part of the cyclic structure. Further, it may be a compound having a plurality of acid anhydride structures in one molecule. Specific examples of the cyclic acid anhydride used in the present invention include succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, Cyclopentanetetracarboxylic dianhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4,5,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phenyl Succinic anhydride, 2-phenylglutaric anhydride, etc. can be mentioned. Of these, succinic anhydride, glutaric anhydride, and maleic anhydride are preferable. These acid anhydrides may be used in combination of two or more.
In addition, content of a cyclic acid anhydride is 0.01 to 10 weight% of the total amount of a mixed non-aqueous solvent and a cyclic acid anhydride, Preferably it is 0.05 to 7 weight%.
[0015]
The electrolytic solution used in the present invention contains a lithium salt as a solute. The lithium salt is not particularly limited as long as it can be used as a solute of the electrolytic solution. Specific examples thereof include an inorganic lithium salt selected from LiClO ₄ , LiPF ₆ , and LiBF _4, or LiCF ₃ SO _3. Fluorine-containing organic materials such as LiN (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ CF ₂ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), LiC (CF ₃ SO ₂ ) ₃ A lithium salt can be mentioned. Two or more kinds of these solutes may be mixed and used.
The molar concentration of the lithium salt in the electrolytic solution is desirably 0.5 to 3.0 mol / liter. If it is less than 0.5 mol / liter or more than 3.0 mol / liter, the electric conductivity of the electrolytic solution is low, and the performance of the battery is deteriorated.
[0016]
The positive electrode used in the present invention is mainly composed of a lithium manganese composite oxide (hereinafter sometimes referred to as composite oxide (A)). In particular, lithium manganese composite oxide having a spinel structure is preferable. Such a lithium manganese composite oxide is preferably one in which a part of the manganese site is substituted. In particular, those substituted with typical elements are preferred. Typical elements that substitute for such manganese sites include Li, B, Na, Mg, Al, Ca, Zn, Ga, Ge, and the like. Of course, it is possible to replace the manganese site with a plurality of elements. Li, Mg, Al, and Ga are preferable as manganese site substitution elements, and aluminum and / or lithium are particularly preferable. The substitution amount of the typical element is preferably 0.03 mol or more in 2 mol of manganese, more preferably 0.05 mol or more, and most preferably 0.07 mol or more.
[0017]
Particularly preferred lithium manganese composite oxide (A) is represented by the general formula:
[Expression 1]
Li [Mn (2-x) AlyLiz] O ₄
[0019]
(Wherein x, y and z are each a number of 0 or more, and x = y + z, where y and z are not 0 at the same time).
Here, y is usually 0.5 or less, preferably 0.25 or less, and usually 0.1 or more. Z is usually 0.1 or less, preferably 0.08 or less, and usually 0.02 or more. If y and z are too small, the high temperature characteristics may be deteriorated. On the other hand, if y and z are too large, the capacity tends to decrease.
[0020]
In the above, the oxygen atom of the composite oxide (A) may have nonstoichiometry, and a part of the oxygen atom may be substituted with a halogen element such as fluorine.
The specific surface area of the composite oxide (A) of the present invention is preferably 2 m ² / g or less, more preferably 1.5 m ² / g or less, and most preferably 1 m ² / g or less. If the specific surface area is too large, the improvement effect is diminished.
[0021]
Furthermore, when the positive electrode in the present invention is mixed with a lithium nickel composite oxide having a layered structure (hereinafter sometimes referred to as composite oxide (B)), it improves cycle characteristics and storage characteristics in a high temperature atmosphere. It has also been found that it can be allowed to. As the composite oxide (B), one having a basic composition formula LiNiO ₂ is generally used. Similar to the composite oxide (A), it is preferable that a part of nickel in the composite oxide (B) is substituted. Preferable elements for the substitution element include metal elements such as Al, Fe, Sn, Cr, Cu, Ti, Zn, Co, and Mn. Of course, it is also possible to replace nickel sites with a plurality of elements. In particular, it is preferably substituted with aluminum and / or cobalt.
[0022]
Particularly preferred composite oxide (B) is represented by the general formula:
[Expression 2]
Li [Ni (1-p) CoqAlr] O ₂
[0024]
(Wherein p, q and r are each a number of 0 or more, and p = q + r, where q and r are not 0 at the same time). Here, q and r are each independently usually 0.5 or less, preferably 0.25 or less, and usually 0.1 or more. R is usually 0.1 or less, preferably 0.08 or less, and usually 0.02 or more. If q or r is too small, the high temperature characteristics tend to be poor, while if too large, the capacity tends to decrease.
[0025]
In the above, the oxygen atom of the composite oxide (B) may have nonstoichiometry, and a part of the oxygen element may be substituted with a halogen element such as fluorine.
The specific surface area of the composite oxide (B) is preferably 1 m ² / g or more, more preferably 2 m ² / g or more, and most preferably 3 m ² / g or more. When the specific surface area of the composite oxide (B) is small, the effect of improving the high temperature characteristics is low.
[0026]
The upper limit of the ratio of the composite oxide (B) to the composite oxide (A) is preferably 60% by weight or less, more preferably 50% by weight or less, and most preferably 30% by weight or less. The lower limit is preferably 5% by weight or more, more preferably 10% by weight or more. If the mixing ratio of the lithium nickel composite oxide (B) is too small, the effect of improving the high temperature characteristics tends to be small, and conversely if too large, there may be problems in terms of cost increase and safety.
[0027]
The particle size of the composite oxide (A) or (B) or these composites is usually 0.1 μm or more, preferably 0.2 μm or more, more preferably 0.3 μm or more, and usually 30 μm or less. Preferably it is 10 micrometers or less, More preferably, it is 5 micrometers or less. The specific surface area of these nitrogen adsorption method is usually 0.3 m ² / g or more, and usually less than 15 m ² / g. If the particle size is too small or the specific surface area is large, the cycle deterioration of the battery may be increased, or a safety problem may occur. If the particle size is too large or the specific surface area is too small, the internal resistance of the battery may increase and output may be difficult.
[0028]
The positive electrode is usually formed by forming a positive electrode mixture layer containing an active material, a binder and a conductive agent on a current collector. The positive electrode mixture layer can be usually obtained by preparing a slurry containing the above-described constituents and applying and drying the slurry on a current collector.
As the binder used for the positive electrode, for example, polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, EPDM (ethylene-propylene-diene terpolymer), SBR (styrene-butadiene rubber), Examples thereof include NBR (acrylonitrile-butadiene rubber), fluororubber, polyvinyl acetate, polymethyl methacrylate, polyethylene, and nitrocellulose.
[0029]
Examples of the conductive agent contained in the positive electrode mixture layer include graphite such as natural graphite and artificial graphite, carbon black such as acetylene black, and amorphous carbon such as needle coke.
[0030]
As the slurry solvent, an organic solvent that dissolves or disperses the binder is usually used. Specific examples thereof include N-methylpyridone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N, N-dimethylaminopropylamine, and tetrahydrofuran. Moreover, a dispersing agent, a thickener, etc. can be added to water, and an active material can also be slurried with latex, such as SBR.
[0031]
As the material of the positive electrode current collector, a metal such as aluminum, titanium, or tantalum or an alloy thereof is used. Among these, since aluminum or its alloy is lightweight, it is preferable in terms of energy density.
[0032]
The negative electrode material constituting the battery is not particularly limited as long as it includes a carbonaceous material capable of occluding and releasing lithium, and specific examples thereof include, for example, pyrolysis products of organic matter under various pyrolysis conditions. A certain amorphous carbon material, artificial graphite, natural graphite, etc. are mentioned.
For amorphous carbon materials, the d value (interlayer distance) of the lattice plane (002 plane) determined by X-ray diffraction by the Gakushin method is 0.34 to 0.38 nm, more preferably 0.34 to 0.37 nm. Particularly preferred is one having a thickness of 0.34 to 0.36 nm. The crystallite size (Lc) determined by X-ray diffraction is preferably 15 nm or less, more preferably 10 nm or less, and most preferably 5 nm or less. The median diameter is 1 to 50 μm, preferably 2 to 40 μm, more preferably 3 to 30 μm, and still more preferably 5 to 25 μm, as a median diameter measured by a laser diffraction / scattering method. The true density is preferably 2.1 g / cc or less.
[0033]
For graphite-based materials such as artificial graphite and natural graphite, artificial graphite produced by high-temperature heat treatment of graphitizable pitch obtained from various raw materials, graphitized mesophase spherules, graphitized mesophase pitch-based carbon fiber and purified natural graphite Alternatively, materials obtained by performing various surface treatments including pitch on these graphites are mainly used.
[0034]
These graphite materials have a lattice plane (002 plane) d value (interlayer distance) of 0.335 to 0.34 nm, more preferably 0.335 to 0.337 nm, as determined by X-ray diffraction using the Gakushin method. Is preferred. These graphite materials have an ash content of 1% by weight or less, more preferably 0.5% by weight or less, most preferably 0.1% by weight or less, and a crystallite size (Lc) determined by X-ray diffraction by the Gakushin method. It is preferable that it is 30 nm or more. Furthermore, the crystallite size (Lc) is more preferably 50 nm or more, and most preferably 100 nm or more. Further, the median diameter of the graphite material is 1 to 100 μm, preferably 3 to 50 μm, more preferably 5 to 40 μm, and still more preferably 7 to 30 μm as a median diameter by a laser diffraction / scattering method. The BET specific surface area of the graphite material is 0.3-25.0 m ² / g, preferably 0.5-20.0 m ² / g, more preferably 0.7-15.0 m ² / g, preferably from 0.8~10.0m ² / g. The intensity of the peak P _A (peak intensity I _A) in a range of 1580～1620Cm ^-1 in the Raman spectrum analysis using an argon ion laser beam and peak in the range of 1350 ^-1 P _B (peak intensity I _B) the ratio R = I _B / I _a is preferably 0 to 1.2, the half-value width of the peak in the range of 1580～1620Cm ^-1 is 26cm ^-1 or less, and particularly preferably between 25 cm ^-1 or less.
[0035]
The method for producing a negative electrode using these negative electrode materials is not particularly limited, and the negative electrode can be produced according to the method for producing a positive electrode.
The negative electrode current collector is made of a metal such as copper, nickel, and stainless steel. Among these, a copper foil is preferable from the viewpoint of easy processing into a thin film and cost.
The material and shape of the separator used in the battery of the present invention are not particularly limited. However, it is preferable to select from materials that are stable with respect to the electrolytic solution and have excellent liquid retention properties, and it is preferable to use a porous sheet or a nonwoven fabric made of a polyolefin such as polyethylene or polypropylene.
[0036]
The method for producing the battery of the present invention having at least a negative electrode, a positive electrode, and a non-aqueous electrolyte solution is not particularly limited, and can be appropriately selected from commonly employed methods.
In addition, the shape of the battery is not particularly limited, and a cylinder type in which a sheet electrode and a separator are spiraled, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a coin type in which a pellet electrode and a separator are stacked, and the like are used. Is possible.
[0037]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples unless it exceeds the gist.
[0038]
Example 1
As a positive electrode active material, 6 parts by weight of carbon black and 9 parts by weight of polyvinylidene fluoride KF-1000 (trade name, manufactured by Kureha Chemical Co., Ltd.) are mixed with 85 parts by weight of lithium manganese composite oxide having a spinel structure, and N— The slurry dispersed in methyl-2-pyrrolidone and applied in a slurry form was uniformly applied on a positive electrode current collector aluminum foil having a thickness of 20 μm, dried, and then punched into a disk shape having a diameter of 12.5 mm to form a positive electrode. .
As the negative electrode active material, the d value of the lattice plane (002 plane) in X-ray diffraction is 0.336 nm, the crystallite size (Lc) is 100 nm or more (264 nm), the ash content is 0.04% by weight, by the laser diffraction / scattering method A median diameter of 17 μm, a BET specific surface area of 8.9 m ² / g, and a peak spectrum P _A (peak intensity I _A ) in the range of 1580 to 1620 cm ⁻¹ and 1350 to 1370 cm ^{− in} Raman spectrum analysis using an argon ion laser beam. artificial graphite intensity ratio R = I _B / I _a of the ^first range of peak P _B (peak intensity I _B) is the half width of the peak in the range of 0.15,1580～1620Cm ^-1 is 22.2Cm ^-1 5 parts by weight of polyvinylidene fluoride is mixed with 95 parts by weight of powder KS-44 (trade name, manufactured by Timcal), and dispersed with N-methyl-2-pyrrolidone to form a slurry. The resulting product was uniformly applied onto a negative electrode current collector 18 μm thick copper foil, dried, and then punched into a disk shape having a diameter of 12.5 mm to form a negative electrode.
[0039]
For the electrolyte, lithium hexafluorophosphate (LiPF ₆ ) that was sufficiently dried under a dry argon atmosphere was used as the solute, and succinic anhydride was added to a mixture of ethylene carbonate and diethyl carbonate (35:65 weight ratio). It was prepared by dissolving at a rate of 2% by weight and further dissolving LiPF ₆ at a rate of 1 mol / liter.
Using these positive electrode, negative electrode, and electrolytic solution, the positive electrode was accommodated in a stainless steel can that also serves as a positive electrode conductor, and the negative electrode was placed thereon via a separator impregnated with the electrolytic solution. The can body and a sealing plate that also serves as the negative electrode conductor were caulked and sealed via an insulating gasket to produce a coin-type battery.
[0040]
(Comparative Example 1)
A coin-type battery was manufactured in the same manner as in Example 1 except that an electrolyte prepared by dissolving LiPF ₆ at a ratio of 1 mol / liter in a mixture of ethylene carbonate and diethyl carbonate (35:65 weight ratio) was used. Produced.
[0041]
(Example 2)
As a negative electrode active material, instead of the artificial graphite powder KS-44, d on the lattice plane (002 plane) in X-ray diffraction obtained by firing coal tar pitch at 1100 ° C. for 3 hours in an inert atmosphere and then crushing. Implementation was performed except that amorphous carbon powder having a value of 0.344 nm, a crystallite size (Lc) of 2.39 nm, a median diameter by laser diffraction / scattering method of 16 μm, and a true density of 2.1 g / cc was used. A negative electrode was produced in the same manner as in Example 1 to produce a coin-type battery.
[0042]
(Comparative Example 2)
A coin-type battery was prepared in the same manner as in Example 2 except that an electrolyte prepared by dissolving LiPF ₆ at a ratio of 1 mol / liter in a mixture of ethylene carbonate and diethyl carbonate (35:65 weight ratio) was used. Produced.
The batteries of Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to a charge / discharge test at 50 ° C. with a constant current of 1.0 mA and a charge end voltage of 4.2 V and a discharge end voltage of 3.0 V.
The discharge capacity maintenance rate in each battery is shown in FIG.
As is apparent from FIG. 1, it is clear that these examples have improved capacity retention ratios and excellent cycle characteristics even when cycling at a relatively high temperature of 50 ° C.
[0043]
【The invention's effect】
According to the present invention, in a non-aqueous electrolyte secondary battery using a lithium manganese composite oxide as a positive electrode, a battery having excellent cycle characteristics and storage characteristics can be produced even in a high temperature atmosphere.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the number of charge / discharge cycles at 50 ° C. and the discharge capacity retention rate in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention.

Claims (3)

A positive electrode mainly composed of a lithium manganese composite oxide having a spinel structure capable of occluding and releasing lithium ions, a negative electrode mainly comprising a carbon material capable of occluding and releasing lithium ions, and a ring A non-aqueous electrolyte used in a non-aqueous electrolyte secondary battery comprising at least an electrolyte obtained by dissolving a lithium salt in a mixed non-aqueous solvent containing at least a carbonate and a chain carbonate, comprising succinic anhydride, Glutaric anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3 , 4,5,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic acid Things, phenyl succinic anhydride, 2-phenyl contains at least one cyclic acid anhydride selected from glutaric anhydride group consisting of compounds, cyclic acid anhydride to the total amount of the mixed nonaqueous solvent and a cyclic acid anhydride The non-aqueous electrolyte solution is characterized in that the ratio of 0.01 to 10% by weight and 95% by weight or more of the mixed non-aqueous solvent is a cyclic carbonate and a chain carbonate.   The non-aqueous electrolyte solution according to claim 1, wherein the mixed non-aqueous solvent contains 20% by weight or more of cyclic carbonate and chain carbonate, respectively, and 95% by weight or more of the mixed non-aqueous solvent is these carbonates. A positive electrode mainly composed of a lithium manganese composite oxide having a spinel structure capable of occluding and releasing lithium ions, a negative electrode mainly comprising a carbon material capable of occluding and releasing lithium ions, and a ring and at least configured nonaqueous electrolyte secondary batteries from a carbonate and a linear carbonate by dissolving a lithium salt in at least comprising mixing a nonaqueous solvent electrolyte, the electrolyte solution is succinic anhydride, glutaric anhydride Acid, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride, cyclopentanetetracarboxylic dianhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 3,4 , 5,6-tetrahydrophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, phenyl Haq acid anhydride, 2-phenyl is selected from glutaric anhydride group consisting of compounds containing at least one cyclic acid anhydride, the ratio of cyclic acid anhydride to the total amount of the mixed nonaqueous solvent and a cyclic acid anhydride A non-aqueous electrolyte secondary battery comprising 0.01 to 10% by weight and 95% by weight or more of the mixed non-aqueous solvent is a cyclic carbonate and a chain carbonate.

Images