Abstract: A subject for the invention is to provide an electrolyte solution and a secondary battery which are preventd from causing or suffering battery performance deterioration in high-temperature storage or high-temperature trickle charge. The invention relates to a nonaqueous electrolyte solution for a secondary battery which comprises solute, phosphinic ester compound, and nonaqueous organic solvent containing these, characterized in that the content of the phosphinic ester compound has been regulated to a specific amount based on the total weight of the nonaqueous electrolyte solution.

Abstract: A subject for the invention is to provide an electrolyte solution and a secondary battery which are prevented from causing or suffering battery performance deterioration in high-temperature storage or high-temperature trickle charge. The invention relates to a nonaqueous electrolyte solution for a secondary battery which comprises solute, phosphinic ester compound, and nonaqueous organic solvent containing these, characterized in that the content of the phosphinic ester compound has been regulated to a specific amount based on the total weight of the nonaqueous electrolyte solution.

Abstract: A non-aqueous electrolyte solution that contains an organic solvent, and a lithium salt and an electrolyte, that is useful for the preparation of a secondary battery that is equipped with a negative electrode and a positive electrode, each of which is capable of storing and releasing lithium, wherein the non-aqueous electrolyte solution contains partially hydrogenated terphenyl that is a mixture of two or more compounds of which one is diphenylcyclohexane that is present in an amount ranging from 10 to 65 wt % of the partially hydrogenated terphenyl and the partially hydrogenated terphenyl has a solubility of not less than 0.5 wt % in the electrolyte solution at room temperature.

Abstract: The present invention is directed to a non-aqueous electrolyte for lithium secondary battery, having both flame retardancy (self-extinguishing property) or nonflammability (having no flash point) and high conductivity and being electrochemically stable, and a lithium secondary battery using the non-aqueous electrolyte. Specifically, the non-aqueous electrolyte of the present invention comprises a non-aqueous solvent which comprises (a) at least one phosphate selected from (a1) a chain state phosphate and (a2) a cyclic phosphate as an essential component, and which may contain (b1) a cyclic carboxylate and (b2) a cyclic carbonate. Further, the non-aqueous electrolyte comprises the above non-aqueous solvent which further comprises (c1) a vinylene carbonate compound and/or (c2) a vinylethylene carbonate compound, and at least one compound selected from the group consisting of (d1) a cyclic amide compound, (d2) a cyclic carbamate compound, and (d3) a heterocyclic compound.

Abstract: An object of the invention is to provide such a battery that has a high capacity, is excellent in storage characteristics, cycle characteristics and continuous charging characteristics, and is small in gas generation amount, whereby size reduction and improvement in performance of a lithium secondary battery can be attained. The present invention relates to a nonaqueous electrolytic solution comprising a lithium salt and a nonaqueous solvent dissolving the same, wherein the electrolytic solution contains, as the lithium salt, LiPF6 in a concentration of from 0.2 to 2 mole/L, and LiBF4 and/or a compound represented by the following formula (1) in a molar ratio of from 0.005 to 0.4 with respect to LiPF6, and the nonaqueous solvent mainly comprises (1) ethylene carbonate and/or propylene carbonate, (2-1) a symmetric linear carbonate, (2-2) an asymmetric linear carbonate, and (3) vinylene carbonate.

Abstract: An object of the invention is to provide such a battery that has a high capacity, is excellent in storage characteristics, cycle characteristics and continuous charging characteristics, and is small in gas generation amount, whereby size reduction and improvement in performance of a lithium secondary battery can be attained. The present invention relates to a nonaqueous electrolytic solution comprising a lithium salt and a nonaqueous solvent dissolving the same, wherein the electrolytic solution contains, as the lithium salt, LiPF6 in a concentration of from 0.2 to 2 mole/L, and LiBF4 and/or a compound represented by the following formula (1) in a molar ratio of from 0.005 to 0.4 with respect to LiPF6, and the nonaqueous solvent mainly comprises (1) ethylene carbonate and/or propylene carbonate, (2-1) a symmetric linear carbonate, (2-2) an asymmetric linear carbonate, and (3) vinylene carbonate.

Abstract: A subject for the invention is to provide an electrolyte solution and a secondary battery which are prevented from causing or suffering battery performance deterioration in high-temperature storage or high-temperature trickle charge. The invention relates to a nonaqueous electrolyte solution for a secondary battery which comprises solute, phosphinic ester compound, and nonaqueous organic solvent containing these, characterized in that the content of the phosphinic ester compound has been regulated to a specific amount based on the total weight of the nonaqueous electrolyte solution.

Abstract: The object of the present invention is to provide a non-aqueous electrolyte solution for secondary batteries, capable of securing safety of the battery in an overcharged state without affecting adversely to battery characteristics such as a low-temperature characteristics and storing characteristics.