Abstract: A nonaqueous electrolyte secondary battery includes an electrode assembly and an electrolyte solution. The electrode assembly is impregnated with at least part of the electrolyte solution. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The separator separates the positive electrode and the negative electrode from each other. The negative electrode includes a negative electrode active material. The negative electrode active material includes graphite. The following relation of a formula (1) is satisfied: “1.60?NPR/AAR?2.55”. “NPR” represents a ratio of a negative electrode charging capacity to a positive electrode charging capacity. “AAR” represents a ratio of an effective discharging capacity of the negative electrode to a total of a capacity corresponding to an amount of inactive lithium adhered to the negative electrode and the effective discharging capacity of the negative electrode.

Abstract: A nonaqueous electrolyte secondary battery includes an electrode assembly and an electrolyte solution. The electrode assembly is impregnated with at least part of the electrolyte solution. The electrode assembly includes a positive electrode, a negative electrode, and a separator. The separator separates the positive electrode and the negative electrode from each other. The negative electrode includes a negative electrode active material. The negative electrode active material includes graphite. The following relation of a formula (1) is satisfied: “1.60?NPR/AAR?2.55”. “NPR” represents a ratio of a negative electrode charging capacity to a positive electrode charging capacity. “AAR” represents a ratio of an effective discharging capacity of the negative electrode to a total of a capacity corresponding to an amount of inactive lithium adhered to the negative electrode and the effective discharging capacity of the negative electrode.

Abstract: In a cross section parallel to a thickness direction of a negative electrode active material layer, an average tortuosity ratio is 1.5 to 2.5. The average tortuosity ratio is calculated by the following formula: “R=B/A”. In the formula, “R” represents the average tortuosity ratio. “B” represents an average value of lengths of shortest routes each extending from a contact point between a negative electrode substrate and a negative electrode active material particle to a surface of the negative electrode active material layer along contour lines of a plurality of negative electrode active material particles. “A” represents an average value of a thicknesses of the negative electrode active material layer.

Abstract: A nonaqueous secondary battery includes a current cutoff mechanism that cuts off a current in a short period of time in response to a rise in pressure inside a battery outer body in at least one of a conductive path through which a current is taken out from a positive electrode plate to outside of the battery and a conductive path through which a current is taken out from a negative electrode plate to outside of the battery. At least one type selected from an oligomer containing a cyclohexyl group and a phenyl group, a modified product of the oligomer containing a cyclohexyl group and a phenyl group, a polymer containing a cyclohexyl group and a phenyl group, and a modified product of the polymer containing a cyclohexyl group and a phenyl group is present on the surface of the positive electrode plate.

Abstract: A nonaqueous electrolyte secondary battery includes: a stacked electrode assembly formed by stacking a plurality of layers of a positive electrode plate and a plurality of layers of a negative electrode plate with a separator interposed therebetween; a nonaqueous electrolyte; and an aluminum laminated outer body that stores the stacked electrode assembly and into which the nonaqueous electrolyte is poured. The positive electrode plate contains a positive electrode active material. The negative electrode plate contains a negative electrode active material. The stacked electrode assembly includes an inorganic particle layer containing a binder and inorganic particles between the positive electrode plate and the separator or between the negative electrode plate and the separator, or both. The nonaqueous electrolyte is also prepared by adding LiPF2O2 thereto.

Abstract: A nonaqueous electrolyte secondary battery includes: a stacked electrode assembly formed by stacking a plurality of layers of a positive electrode plate and a plurality of layers of a negative electrode plate with a separator interposed therebetween; a nonaqueous electrolyte formed by dissolving LiPF6 at 1.5 mol/L into a mixed solvent of EC, EMC, and DMC; and an aluminum laminated outer body that stores the stacked electrode assembly and into which the electrolyte is poured. The ratio of the EC, the EMC, and the DMC is 36% by volume, 31% by volume, and 33% by volume, respectively, to the total amount of the mixed solvent. The nonaqueous electrolyte contains LiPF2O2.

Abstract: A nonaqueous secondary battery includes a current cutoff mechanism that cuts off a current in a short period of time in response to a rise in pressure inside a battery outer body in at least one of a conductive path through which a current is taken out from a positive electrode plate to outside of the battery and a conductive path through which a current is taken out from a negative electrode plate to outside of the battery. At least one type selected from an oligomer containing a cyclohexyl group and a phenyl group, a modified product of the oligomer containing a cyclohexyl group and a phenyl group, a polymer containing a cyclohexyl group and a phenyl group, and a modified product of the polymer containing a cyclohexyl group and a phenyl group is present on the surface of the positive electrode plate.