Abstract: A nonaqueous electrolyte rechargeable battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode and the negative electrode occlude and discharge lithium irons. The nonaqueous electrolyte contains an additive and a polycyclic aromatic hydrocarbon. The additive includes an organic solvent having a donor number of 18 to 24. A content of the polycyclic aromatic hydrocarbon is 0% to 2.0% of a total mass of the nonaqueous electrolyte.

Abstract: A lithium-ion secondary battery includes: a first cathode active material having a polyanion structure which stores and releases a lithium ion; and a second cathode active material having a lithium diffusion coefficient different from a lithium diffusion coefficient of the first cathode active material. The second cathode active material has a layered rock salt-type structure. A discharge curve of the first cathode material and a discharge curve of the second cathode material intersect with each other at at least two points.

Abstract: A cathode active material for a nonaqueous electrolyte secondary battery includes a core part and a shell part arranged to a surface of the core part. The core part includes an inorganic oxide having a polyanion structure. The inorganic oxide is LixMnyM1-yXO4, in which M is at least one of Co, Ni, Fe, Cu, Cr, Mg, Ca, Zn, and Ti, X is at least one of P, As, Si, and Mo, and 0?x<1.0 and 0.5?y?1.0. The inorganic oxide has a maximum mass change ratio G1 in a temperature range from a room temperature to 250° C. when heated under inert atmosphere, and has a maximum mass change ratio G2 in a temperature range from 350° C. to 500° C. when heated under inert atmosphere. A difference between the maximum mass change ratio G2 and the maximum mass change ratio G1 is less than or equal to 5%.

Abstract: A positive electrode active material includes a conductive matrix and a lithium metal compound of a polyanion structure provided on the surface of the conductive matrix. The lithium metal compound is expressed as Li?M0?X?O4-?Z?, in which: M0 is one or more selected from Mn, Co, Ni, Fe, Cu, Cr, Mg, Ca, Zn, and Ti; X is one or more selected from P, As, Si, Mo, and Ge; Z is one or more selected from Al, Mg, Ca, Zn, and Ti, being optionally includable; ? satisfies 0???2.0; ? satisfies 0???1.5; ? satisfies 1???1.5; and ? satisfies 0???1.5.

Abstract: An apparatus for calculating a residual capacity of a secondary battery is provided. The apparatus calculates the residual capacity of energy in the secondary battery which is charged/discharged. The apparatus includes an arithmetic unit which estimates and calculates a first residual capacity based on a charge/discharge voltage corresponding to a residual capacity of the secondary battery, calculates a second residual capacity based on an integrated value of a charge/discharge current of the secondary battery, weights the charge/discharge voltage of the secondary battery with the first residual capacity or the second residual capacity according to the voltage changing rate, and combines the results of the weighting to obtain the residual capacity of the secondary battery.

Abstract: A nonaqueous electrolyte rechargeable battery includes a positive electrode, a negative electrode and a nonaqueous electrolyte. The nonaqueous electrolyte contains a film forming agent, and at least two films are formed in layers at least at a part of a surface of the negative electrode in accordance with charging and discharging of the nonaqueous electrolyte rechargeable battery. The film forming agent includes at least one kind of lithium salt having an oxalate complex. Among the at least two films, an innermost film is an oxalate complex-derived film that is derived from the oxalate complex and has a thickness equal to or greater than a film formed on an outer side of the innermost film. The film forming agent includes a compound having a LUMO level higher than the lithium salt incorporated in the oxalate complex-derived film as a high LUMO film forming agent.

Abstract: A nonaqueous electrolyte rechargeable battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode and the negative electrode occlude and discharge lithium irons. The nonaqueous electrolyte contains an additive and a polycyclic aromatic hydrocarbon. The additive includes an organic solvent having a donor number of 18 to 24. A content of the polycyclic aromatic hydrocarbon is 0% to 2.0% of a total mass of the nonaqueous electrolyte.

Abstract: An apparatus for calculating a residual capacity of a secondary battery is provided. The apparatus calculates the residual capacity of energy in the secondary battery which is charged/discharged. The apparatus includes an arithmetic unit which estimates and calculates a first residual capacity based on a charge/discharge voltage corresponding to a residual capacity of the secondary battery, calculates a second residual capacity based on an integrated value of a charge/discharge current of the secondary battery, weights the charge/discharge voltage of the secondary battery with the first residual capacity or the second residual capacity according to the voltage changing rate, and combines the results of the weighting to obtain the residual capacity of the secondary battery.