Abstract: The present invention provides an electrolyte for lithium secondary batteries that allows the batteries to operate safely at a charging voltage up to 4.35V, wherein the electrolyte comprises a combination of a fluoroethylene carbonate compound and a linear ester compound as solvent. Also, the present invention provides a lithium secondary battery that can operate at a charging voltage up to 4.35V, which comprises a positive electrode, a negative electrode and an electrolyte, wherein the electrolyte comprises fluoroethylene carbonate compound and linear ester compound as solvent.

Abstract: This invention provides an electrochemical cell comprising a housing having disposed therewithin, an electrolyte, and a multi-layer article at least partially immersed in the electrolyte; the multi-layer article comprising a first metallic current collector, a first electrode material in electrically conductive contact with the first metallic current collector, a second electrode material in ionically conductive contact with the first electrode material, a porous separator disposed between and contacting the first electrode material and the second electrode material; and, a second metallic current collector in electrically conductive contact with the second electrode material, wherein the porous separator comprises a nanoweb consisting essentially of a plurality of nanofibers of a fully aromatic polyimide. Also provided is a process for preparing the multi-layer article. Further provided is an electrochemical cell wherein the separator is a polyimide nanoweb with enhanced properties.

Abstract: Desirable electrolyte compositions are described that are suitable for high voltage lithium ion batteries with a rated charge voltage at least about 4.45 volts. The electrolyte compositions can comprise ethylene carbonate and solvent composition selected from the group consisting of dimethyl carbonate, methyl ethyl carbonate, ?-butyrolactone, ?-valerolactone or a combination thereof. The electrolyte can further comprise a stabilization additive. The electrolytes can be effectively used with lithium rich positive electrode active materials.

Abstract: A quaternary ammonium salt of the formula (1), a composition containing the quaternary ammonium salt and an organic solvent, and an electrochemical device using the salt wherein R1 and R2 are both methyl and X? is BF4? or N(CF3SO2)2?.

Abstract: A lithium ion battery electrolyte for use in lithium ion batteries. The electrolyte includes LiPF6, LiBF4, LiB(C2O4)2, or a related salt dissolved in a mixture of organic carbonate, ether or ester solvents with low concentrations of oxidatively unstable additives such that the additives react with a surface of cathode particles to generate a passivation film which prevents oxidation of the electrolyte by the cathode. The additive is a polymerizable organic molecule selected from 2,3-dihydrofuran (2,3-DHF), 2,5-dihydrofuran (2,5-DHF), vinylene carbonate (VC), vinyltrimethoxysilane (VTMS), dimethyl vinylene cabonate (DMVC), and gamma-buyrolactone, or related unsaturated ethers, esters, or carbonates.

Abstract: A non-aqueous electrolyte for a secondary battery includes a solvent and an electrolyte containing a lithium salt. The solvent contains 4-fluoroethylene carbonate and a chain carboxylic ester represented by the formula R1COOR2, where R1 and R2 are alkyl groups having 3 or less carbon atoms. The amount of the 4-fluoroethylene carbonate is 7 volume % or greater with respect to the total amount of the solvent.

Abstract: This invention relates to a non-aqueous electrolyte for a cell and an electrolyte for a polymer cell in which the risk of igniting-firing an aprotic organic solvent retained in the cell and leaked out of the cell through vaporization or the like when the temperature of the cell rises abnormally is reduced, and to a non-aqueous electrolyte for a cell and an electrolyte for a polymer cell comprising an aprotic organic solvent and a compound containing phosphorus and/or nitrogen in its molecule and having a difference of a boiling point from that of the aprotic organic solvent of not more than 25° C.

Abstract: The present invention improves the cycle characteristics of a non-aqueous electrolyte secondary cell that uses lithium cobalt oxide as a positive electrode active material. To this end, an element different from cobalt such as zirconium and titanium is added to the lithium cobalt oxide, acting as the positive electrode active material. The non-aqueous electrolyte contains a non-aqueous solvent containing diethyl carbonate at 10 to 30 volume percent on a base of 25 degree Celsius and contains an electrolyte salt.

Abstract: A rechargeable lithium-ion battery includes a positive electrode that includes a first current collector and a first active material. The battery also includes an electrolyte and a negative electrode that includes a second current collector and a second active material, where the second active material includes a lithium titanate material. The positive electrode has a first capacity and the negative electrode has a second capacity, the second capacity being less than the first capacity such that the rechargeable lithium-ion battery is negative-limited.

Abstract: An electrochemical cell comprises as an anode, a lithium transition metal oxide or sulphide compound which has a [B2]X4n? spinel-type framework structure of an A[B2]X4 spinel wherein A and B are metal cations selected from Li, Ti, V, Mn, Fe and Co, X is oxygen or sulphur, and n? refers to the overall charge of the structural unit [B2]X4 of the framework structure. The transition metal cation in the fully discharged state has a mean oxidation state greater than +3 for Ti, +3 for V, +3.5 for Mn, +2 for Fe and +2 for Co. The cell includes as a cathode, a lithium metal oxide or sulphide compound. An electrically insulative lithium containing liquid or polymeric electronically conductive electrolyte is provided between the anode and the cathode.

Abstract: Disclosed is a lithium secondary battery comprising a cathode including a lithium-containing transition metal oxide, an anode including a carbon-based material, and a non-aqueous electrolyte with addition of a compound of formula (1). Incorporation of the compound (1) into the electrolyte significantly improves the high-temperature performance and cycle life characteristics of the battery.

Abstract: An organic electrolytic solution and a lithium battery employing the same are provided. The organic electrolytic solution includes a lithium salt, an organic solvent containing a first solvent having a high dielectric constant and a second solvent having a low boiling point, and a surfactant including a hydrophobic portion having an aromatic group. The organic electrolytic solution effectively prevents the electrolytic solution from contacting the anode, thereby suppressing side reactions on the anode surface and improving discharge capacity, charge/discharge efficiency, lifespan, and battery reliability.

Abstract: It is aimed at providing: a negative electrode material for a nonaqueous secondary battery, which has a higher capacity, is low in irreversible capacity upon initial charge and discharge, and has excellent cycle characteristics; and a nonaqueous secondary battery adopting the negative electrode material. The object is achieved by: a multi-layer structured carbonaceous material obtained by mixing graphitic carbon particles with an organic compound and by thermally treating the mixture, wherein loop structures are present at an edge portion of each of the graphitic carbon particles, and wherein the graphitic carbon particles have carbonized products of the organic compound affixed to surfaces of the particles, respectively, while maintaining the loop structures; and a nonaqueous secondary battery adopting the multi-layer structured carbonaceous material.

Abstract: Provided is a non-aqueous electrolyte capable of favorably suppressing the gas generation during storage in a high temperature environment and during charge/discharge cycling of a non-aqueous electrolyte secondary battery. The non-aqueous electrolyte includes a non-aqueous solvent and a solute dissolved in the non-aqueous solvent, wherein: the non-aqueous solvent includes ethylene carbonate, propylene carbonate, diethyl carbonate, and an additive; the additive includes a sultone compound and a cyclic carbonate having a C?C unsaturated bond; a weight percentage WPC of the propylene carbonate relative to a total of the ethylene carbonate, propylene carbonate, and diethyl carbonate is 30 to 60% by weight; a ratio WPC/WEC of the weight percentage WPC of the propylene carbonate to a weight percentage WEC of the ethylene carbonate relative to the total satisfies 2.

Abstract: An electrolyte for a lithium ion secondary battery includes a non-aqueous organic solvent; lithium salt; and difluoro oxalato borate and fluoro ethylene carbonate (FEC). The capacity retention property and durability of a lithium ion secondary battery including the electrolyte is excellent even when the battery is left at a high temperature.

Abstract: An organic electrolytic solution and a lithium battery employing the same are provided. The organic electrolytic solution includes a lithium salt, an organic solvent containing a first solvent having a high dielectric constant and a second solvent having a low boiling point, and a surfactant including a hydrophobic portion having an aromatic group. The organic electrolytic solution effectively prevents the electrolytic solution from contacting the anode, thereby suppressing side reactions on the anode surface and improving discharge capacity, charge/discharge efficiency, lifespan, and battery reliability.

Abstract: There is provided a solvent for non-aqueous electrolytic solution of lithium secondary battery comprising a non-fluorine-containing cyclic carbonate (I), a non-fluorine-containing chain carbonate (II) and 1,2-dialkyl-1,2-difluoroethylene carbonate (III), wherein assuming that the total amount of (I), (II) and (III) is 100% by volume, the non-fluorine-containing cyclic carbonate (I) is contained in an amount of 10 to 50% by volume, the non-fluorine-containing chain carbonate (II) is contained in an amount of 49.9 to 89.9% by volume and the 1,2-dialkyl-1,2-difluoroethylene carbonate (III) is contained in an amount of not less than 0.1% by volume and less than 30% by volume. Also, there are provided a non-aqueous electrolytic solution comprising the mentioned solvent and a lithium secondary battery using the non-aqueous electrolytic solution.

Abstract: There is provided an electrolytic solution causing no phase separation even at low temperatures, being excellent in flame retardancy and noncombustibility, assuring high solubility of an electrolyte salt, having a high discharge capacity, being excellent in charge-discharge cycle characteristics and being suitable for electrochemical devices such as lithium ion secondary batteries.

Abstract: In a rechargeable non-aqueous electrolyte secondary battery using positive electrodes, negative electrodes and a non-aqueous electrolytic solution, additives to the electrolytic solution are used in combination, preferably in combination of at least two compounds selected from o-terphenyl, triphenylene, cyclohexylbenzene and biphenyl, and thus there are provided batteries excellent in safety and storage characteristics.

Abstract: The present invention provides a lithium secondary battery which has improved safety, mainly coming from use of an electrolyte solution which is not inflammable at room temperature (20° C.), while not deteriorating output characteristics at low temperatures and room temperature or output maintenance characteristics after storage at high temperature (50° C.). The lithium secondary battery of the present invention, encased in a container, is provided with a cathode and an anode, both capable of storing/releasing lithium ions, a separator which separates these electrodes from each other, and an electrolyte solution containing a cyclic carbonate and a linear carbonate as solvents and a compound such as VC at composition ratios of 18.0 to 30.0%, 74.0 to 81.9% and 0.1 to 1.0%, respectively, based on the whole solvents, all percentages by volume.

Abstract: A nonaqueous electrolyte secondary battery includes a positive electrode containing a positive active material, a negative electrode containing a negative active material and a nonaqueous electrolyte. Characteristically, the positive active material comprises a mixture of a lithium transition metal complex oxide A obtained by incorporating at least Zr and Mg into LiCoO2 and a lithium transition metal complex oxide B having a layered structure and containing at least Ni and Mn as the transition metal.

Abstract: A nonaqueous electrolyte for a lithium secondary battery and a lithium secondary battery including the same are provided. In particular, the nonaqueous electrolyte comprises a compound of chemical formula 1 as an electrolyte additive: NC—(R1)n-A-(R2)m—CN??1 wherein, R1 and R2 represent, respectively, alkylene groups, n and m represent integers of 1 to 10, and A is an aromatic hydrocarbon in which the number of carbons is 5 to 9 or O. When the lithium secondary battery is kept at high voltage and temperature, the electrolyte additive reduces gas generation, thereby reducing battery swelling. Therefore, it is possible to reduce a battery thickness increment rate and to increase discharge capacity at a high temperature.

Abstract: A quaternary ammonium salt of the formula (1), electrolytic solution and electrochemical device using the salt wherein R1 is straight-chain or branched alkyl having 1 to 4 carbon atoms, R2 is straight-chain or branched alkyl having 1 to 3 carbon atoms, and X? is N(CN)2?, SCN?, NO3?, NCO? or NO2?.

Abstract: An organic electrolytic solution is provided which includes a lithium salt, an organic solvent including a first solvent having high permittivity and a second solvent having a low boiling point, and a phosphine oxide compound The phosphine oxide compound imparts flame resistance and good charge/discharge properties, thereby producing a lithium battery that is highly stable and reliable and that has good charge/discharge efficiency.

Abstract: A non-aqueous electrolyte for a secondary battery, including a non-aqueous solvent in which a solute is dissolved, a first additive and a second additive, wherein the first additive is a vinyl monomer having an electron donating group, the second additive is a carbonic acid ester having at least one carbon-carbon unsaturated bond, and an e value, which is a polarization factor of the vinyl monomer having an electron donating group, is a negative value.

Abstract: There are provided a solvent for dissolving an electrolyte salt of lithium secondary battery comprising at least one fluorine-containing solvent (I) selected from the group consisting of a fluorine-containing ether, a fluorine-containing ester and fluorine-containing chain carbonate, 1,2-dialkyl-1,2-difluoroethylene carbonate (II) and other carbonate (III), a non-aqueous electrolytic solution comprising the solvent and an electrolyte salt, and a lithium secondary battery using the non-aqueous electrolytic solution. The solvent for dissolving an electrolyte salt provides a lithium secondary battery being excellent particularly in discharge capacity, rate characteristic and cycle characteristic and has enhanced incombustibility (safety) and the non-aqueous electrolytic solution comprises the solvent and an electrolyte salt.

Abstract: An electrolyte for a lithium secondary battery is provided. The electrolyte improves battery safety, high temperature storage characteristics, and electrochemical properties of lithium batteries. The electrolyte comprises at least one lithium salt and a non-aqueous organic solvent comprising a cyclic carbonate and a lactone-based compound. The lactone based compound comprises substituents selected from the group consisting of alkyl groups, alkenyl groups, alkynyl groups, aryl groups, and combinations thereof. A lithium battery is also provided, which comprises a negative electrode capable of intercalating/deintercalating lithium, a positive electrode capable of intercalating/deintercalating lithium, and an inventive electrolyte.

Abstract: A lithium battery comprises at least a positive electrode containing a material whose lithium insertion and deinsertion potential is lower than or equal to 3.5 Volts in relation to the potential of the Li+/Li couple, a negative electrode and a non-aqueous electrolyte disposed between the positive and negative electrodes. The electrolyte comprises at least a lithium salt dissolved in an aprotic organic solvent wherein a polymerizable additive is added, chosen from carbazol and the derivatives thereof and being used to prevent the battery from operating as soon as the voltage at the terminal connections of the battery reaches a value resulting in polymerization of the additive.

Abstract: In a rechargeable non-aqueous electrolyte secondary battery using positive electrodes, negative electrodes and a non-aqueous electrolytic solution, additives to the electrolytic solution are used in combination, preferably in combination of at least two compounds selected from o-terphenyl, triphenylene, cyclohexylbenzene and biphenyl, and thus there are provided batteries excellent in safety and storage characteristics.

Abstract: A non-aqueous electrolyte solution for a lithium ion secondary battery includes a lithium salt and an organic solvent. The organic solvent includes a carbonate compound, a linear ester compound and a linear ester decomposition inhibitor. This non-aqueous electrolyte solution restrains swelling while improving low temperature charging/discharging characteristics of the secondary battery in comparison to a conventional electrolyte since it contains the linear ester compound and the linear ester decomposition inhibitor. The non-aqueous electrolyte solution may be used in making a lithium ion secondary battery.

Abstract: A lithium secondary battery is intended to suppress deterioration upon storage at high temperature of 50° C. or higher without deteriorating the output characteristics at a room temperature. The battery includes a positive electrode capable of occluding and releasing lithium ions, a negative electrode capable of occluding and releasing lithium ions, a separator disposed between the positive electrode and the negative electrode and an electrolyte, in which the electrolyte contains a compound represented by formula (1) (R?O)nSiR4-n??(Formula 1) where R? represents an alkyl group, R is selected from hydrogen, an alkyl group, an alicyclic group, and an aryl group, each of R? and R may be identical or different from each other, the alkyl group has a straight or branched chain having fewer than 10 carbon atoms, and n is an integer of 1 to 3, and a compound having a polymerizable group in the molecule.

Abstract: A nonaqueous electrolyte battery includes a positive electrode, a negative electrode and a nonaqueous electrolyte. The positive electrode includes a lithium/manganese-containing oxide represented by LiaMnbMcOZ (M is at least one selected from the group consisting of Ni, Co, Al and F, and a, b, c and Z satisfy the following equations: 0?a?2.5, 0<b?1, 0?c?1 and 2?Z?3) and a Fe-containing phosphorous compound having an olivine structure. The negative electrode includes a titanium-containing metal oxide into which lithium ions are inserted and from which lithium ions are extracted.

Abstract: A lithium secondary battery is intended to suppress deterioration upon storage at high temperature of 50° C. or higher without deteriorating the output characteristics at a room temperature. The battery includes a positive electrode capable of occluding and releasing lithium ions, a negative electrode capable of occluding and releasing lithium ions, a separator disposed between the positive electrode and the negative electrode, and an electrolyte. The electrolyte contains a compound having a double bond in the molecule and a compound having a plurality of polymerizable functional groups in the molecule, and the electrolyte contains a compound represented by formula (4): (in which Z1 and Z2 each represent any one of an allyl group, a methallyl group, a vinyl group, an acryl group, and a methacryl group).

Abstract: Disclosed are nonaqueous electrolyte additives, which can improve the safety of a battery upon overcharge of the battery without reducing the performance of the battery, as well as a nonaqueous electrolyte comprising the additives, and a lithium secondary battery comprising the nonaqueous electrolyte. More particularly, disclosed are a nonaqueous electrolyte comprising both fluorobiphenyl and fluorotoluene as additives, and a lithium secondary battery comprising the nonaqueous electrolyte.

Abstract: To provide a novel pentafluorophenyloxy compound, a method for producing same, a nonaqueous electrolyte solution capable of forming a lithium secondary battery having excellent battery characteristics such as electrical capacity, cycling property and storage property, and a lithium secondary battery. A pentafluorophenyloxy compound represented by the general formula (I) shown below, a method for producing same, a nonaqueous electrolyte solution containing same and a lithium secondary battery: wherein R1 represents a —COCO— group, a S?O group or a S(?O)2 group, R2 represents an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group, an aryl group or an aralkyl group with the proviso that at least one of the hydrogen atoms of R2 may be each substituted with a halogen atom and that R2 does not represent an aryl group when R1 represents a —COCO— group.

Abstract: The present invention provides a lithium secondary battery which is improved in cycle characteristics and storage stability at an elevated temperature as well as protection from overcharge. In the battery, generation of a gas is also inhibited to prevent the battery from expansion. A non-aqueous electrolytic solution for the lithium secondary battery has an electrolyte in a non-aqueous solvent. The non-aqueous solvent is composed of a cyclic carbonate compound, a linear carbonate compound and a cyclohexylbenzene compound having a benzene ring to which one or two halogen atoms are attached. A volume ratio of the cyclic carbonate compound and the linear carbonate compound in the non-aqueous solvent is in the range of 20:80 to 40:60, or the non-aqueous solvent further contains a small amount of a branched alkylbenzene compound.

Abstract: Disclosed herewith are an additive mixture for the electrolyte of lithium ion secondary batteries and electrolyte of lithium ion secondary batteries comprising the said additive mixture. The additive mixture comprises biphenyl based compound 0.5-95.4 wt %, cyclohexyl benzene based compound 0.1-93.8 wt %, vinylene carbonate 0.4-93.2 wt %, t-alkyl benzene based compound 0.5-96.5 wt %, and phenyl vinyl sulfone 0.5-95.8% based on total weight of the additive mixture.

Abstract: The present disclosure relates generally to a high capacity cathode material suitable for use in a non-aqueous electrochemical cell that comprises copper manganese oxide, which may be in amorphous or semi-crystalline form, and optionally fluorinated carbon. The present disclosure additionally relates to a non-aqueous electrochemical cell comprising such a cathode material and, in particular, to such a non-aqueous electrochemical cell that can deliver a higher capacity than conventional cell.

Abstract: The invention provides a lithium secondary battery which is excellent in long-term cycle property and in battery characteristics, such as electric capacity and storage property, and a nonaqueous electrolytic solution usable for such a lithium secondary battery. The present invention relates to a lithium secondary battery including a positive electrode, a negative electrode, and a nonaqueous electrolytic solution containing an electrolyte salt dissolved in a nonaqueous solvent, characterized in that the positive electrode is made of a material including a lithium compound oxide, in that the negative electrode is made of a material including graphite, and in that the nonaqueous electrolytic solution contains dialkyl oxalate and further contains vinylene carbonate and/or 1,3-propanesultone, and a nonaqueous electrolytic solution for use in such a battery.

Abstract: Flame retardant electrolyte solutions for rechargeable lithium batteries and lithium batteries including the electrolyte solutions are provided. The flame retardant electrolyte solution includes a lithium salt, a linear carbonate-based solvent, at least one ammonium cation, a phosphoric acid-based solvent, and an additive including oxalatoborate.

Abstract: Disclosed is a lithium secondary battery comprising a cathode including a lithium-containing transition metal oxide, an anode including a carbon-based material, and a non-aqueous electrolyte with addition of a compound of formula (1). Incorporation of the compound (1) into the electrolyte significantly improves the high-temperature performance and cycle life characteristics of the battery.

Abstract: A nonaqueous electrolyte battery includes: a cathode using a composite compound of lithium and transition metals as a positive active material; an anode using a negative active material capable of being doped with and doped from lithium; and a nonaqueous electrolyte interposed between the cathode and the anode. The nonaqueous electrolyte is obtained by dissolving LiMFm (M is an element selected from As, B, P and Sb, and m is an integer located within a range of 4 to 6.) and LiCnF2n+1 SO3 or LiN(CnF2n+1SO2)2 in a nonaqueous solvent including cyclic carbonate or non cyclic carbonate and having unsaturated carbonate added within a range of 0.1 volume % or more and 5 volume % or less, and the concentration of LiCnF2n+1SO3 or LiN(CnF2n+1SO2)2 is located within a range of 1 wt % or more and lower than 10 wt %. Thus, a self-discharge is suppressed and a storage property is improved.

Abstract: A non-aqueous solvent is provided that includes ethylene carbonate in a range from 5% or more to less than 60%, propylene carbonate of 40% or less, and diethyl carbonate of 40% or more, as mass ratios. The non-aqueous electrolyte compositions are formed by further adding an electrolytic salt and, if necessary, unsaturated cyclic carbonic ester and a high molecular compound into the non-aqueous solvent. A non-aqueous electrolyte secondary battery is formed by using the non-aqueous electrolyte compositions.

Abstract: A nonaqueous electrolyte secondary battery 10 according to an embodiment of the invention includes a positive electrode 11, a negative electrode 12, a separator 13 and a nonaqueous electrolyte liquid in which not only the positive electrode 11 contains a positive electrode active material charged at or higher than 4.3 V based on lithium and a halogenated cyclic carbonate is added in the nonaqueous electrolyte liquid, but also an inorganic insulating material particle layer is formed on the surface of at least either of the positive electrode 11, the negative electrode 12 and the separator 13. By employing such a constitution in the present invention, a nonaqueous electrolyte secondary battery using a positive electrode charged at a high electric potential of 4.3 V or more based on lithium in which the amount of a generated gas is small even when the battery is overcharged at higher temperatures, and the impact safety and reliability thereof are high, can be provided.

Abstract: Disclosed is an electrolyte for a rechargeable lithium battery including: a first additive having an oxidation potential of 4.1 to 4.6V; a second additive having an oxidation potential of 4.4 to 5.0V; a non-aqueous organic solvent; and a lithium salt.

Abstract: An electrolyte for a lithium secondary battery includes lithium salts, a non-aqueous organic solvent, and additive compounds, which initiates decomposition at 4V to 5V and show a constant current maintenance plateau region of more than or equal to 0.5V at measurement of LSV (linear sweep voltammetry). The additive compounds added to the electrolyte of the present invention decompose earlier than the organic solvent to form a conductive polymer layer on the surface of a positive electrode by increased electrochemical energy and heat at overcharge. The conductive polymer layer prevents decomposition of the organic solvent. Accordingly, the electrolyte inhibits gas generation caused by decomposition of the organic solvent during high temperature storage, and also improves safety of the battery during overcharge.

Abstract: The present invention provides a paste electrolyte comprising an organic solvent of not high dielectric constant, soluble lithium salts, and clays, with the clays being swollen by the solvent, and rechargeable lithium batteries containing the paste electrolyte. The paste electrolyte according to the present invention can improve the electrochemical properties and cycling stability of rechargeable lithium batteries by limiting the anionic transport between anode and cathode without significantly decreasing the lithium transport rate, particularly during fast charge and discharge.

Abstract: The battery has an electrolyte that includes an organoborate additive and one or more salts in a solvent. The organoborate additive can be present in a concentration less than 0.2 M or less than 0.05 M. A molar ratio of the organoborate additive:one or more salts is in a range of 4:1 to 400:1. In some instances, the solvent includes one or more organic solvents.

Abstract: Disclosed is a lithium secondary battery which is excellent in battery characteristics such as long-term cycle characteristics, capacity and shelf life characteristics. Also disclosed is a nonaqueous electrolyte solution which can be used for such a lithium secondary battery. Specifically disclosed is a nonaqueous electrolyte solution for lithium secondary batteries obtained by dissolving an electrolyte salt in a nonaqueous solvent which is characterized by containing 0.01-10% by weight of a carboxylate compound represented by the general formula (I) below and 0.01-10% by weight or 0.01-10% by volume of a vinylene carbonate and/or 1,3-propane sultone. Also disclosed is a lithium secondary battery using such a nonaqueous electrolyte solution. (In the formula, R2 represents a hydrogen atom or COOR3 group, R1 and R3 respectively represent an alkyl group, a cycloalkyl group, an alkenyl group, an alkynyl group or a phenyl group, and X represents an alkynylene group or an alkenylene group.

Abstract: A non-aqueous electrolyte is provided that includes a non-aqueous solvent and an electrolyte salt, wherein the non-aqueous solvent contains a fluorinated ether (1) represented by the following Formula: HCF2CF2CF2CH2—O—CF2CF2H (1). This non-aqueous electrolyte has good wettability to a polyolefin separator, can provide a battery with excellent load characteristics for a long period, does not easily decompose in the battery under high-temperature storage, and causes little gas generation due to decomposition. Furthermore, a non-aqueous electrolyte secondary battery is provided that includes a positive electrode, a negative electrode, a separator, and the above-described non-aqueous electrolyte.