Abstract: Provided are a secondary battery comprising a separator material capable of achieving a secondary battery with superior high temperature cycle characteristics and a higher energy density, and a method of manufacturing a secondary battery. A separator is evaluated and selected by thermal decomposition gas chromatography (thermal decomposition+GC/MS). In a suitable separator, the value of (the area of Peak 1 exhibiting 1-Decene)/(the area of Peak 2 exhibiting 1-Octene) in a total ion chromatogram (TIC) of the pyrolysate of the separator is 2.05 or less. More preferably, a material in which the value of (the area of Peak 1)/(the area of Peak 2) is 2.00 or less, the value of (the area of Peak 1)/(the area of Peak 3 exhibiting 1-Nonene) is 1.87 or less, and the value of (the area of Peak 3)/(the area of Peak 2) is 1.05 or less is selected, and is used as a separator.

Abstract: A nonaqueous electrolytic secondary battery includes a negative electrode, a positive electrode, and a nonaqueous electrolytic solution including an electrolytic salt dissolved in a nonaqueous solvent. A polymer is added to the nonaqueous electrolytic solution. Also, a method of making a nonaqueous electrolytic secondary battery includes the steps of placing a negative electrode, a positive electrode, and a nonaqueous electrolytic solution including an electrolytic salt dissolved in a nonaqueous solvent, in a battery housing to assemble a battery; and charging and discharging the battery under overcharge conditions or applying a pulse voltage to the battery.

Abstract: A nonaqueous electrolytic secondary battery includes a negative electrode, a positive electrode, and a nonaqueous electrolytic solution including an electrolytic salt dissolved in a nonaqueous solvent. A polymer is added to the nonaqueous electrolytic solution. Also, a method of making a nonaqueous electrolytic secondary battery includes the steps of placing a negative electrode, a positive electrode, and a nonaqueous electrolytic solution including an electrolytic salt dissolved in a nonaqueous solvent, in a battery housing to assemble a battery; and charging and discharging the battery under overcharge conditions or applying a pulse voltage to the battery.