| 摘要 |
PROBLEM TO BE SOLVED: To provide a lithium ion battery which achieves the effect of addition of a coat-forming agent sufficiently, and shows a superior high-rate cycle characteristic even under a low-temperature environment.SOLUTION: A lithium ion battery including a wound electrode body is provided according to the present invention. In the battery, a negative electrode active material layer 24 is formed to be larger, in width, than a positive electrode active material layer 14, and has an opposing portion 24c opposed to the positive electrode active material layer 14, and non-opposing portions 24n which are not opposed to the positive electrode active material layer. In an opposing central region 24a of the opposing portion 24c, excluding regions 24b next to the non-opposing portions, measurement lines each in a straight line form running from one end to the other end in a direction of the width are set. When measuring a resistance along each measurement line, a point where the resistance becomes a maximum is present in a length region within 15% with respect to a center Cin the opposing central region 24a in the width direction as to any measurement line.SELECTED DRAWING: Figure 3 |
