二次電池

Japanese Patent JP5737595

B2

PROBLEM TO BE SOLVED: To provide a secondary battery in which unevenness in the concentration of an electrolyte impregnated in a wound electrode body is reduced.SOLUTION: A secondary battery provided by the present invention includes a flat shaped wound electrode body consisting of a long cathode sheet and a long anode sheet which are wound via two separator sheets, the wound electrode body having load applied to its flat surface when in use. This secondary battery is such that when, referring to the cross section of the wound electrode body, the length of the flat portion between two inflection points of the separator sheet in the innermost section thereof is assumed to be L and the distance from a straight line at bent end orthogonal to the flat portion starting from one of the inflection points to the beginning end of winding of the anode sheet is assumed to be X, then X/L is in the range of 1/100 to 20/100, and that when the distance from the straight line at bent end to the beginning end of winding of the cathode sheet is assumed to be Y, then X