Secondary battery

摘要

A secondary battery having an excellent capacity maintenance factor or charging/discharging efficiency is provided. A lithium-ion battery comprises an electrode group that a positive electrode and a negative electrode which respective of active materials for the positive and negative electrodes is coated on both surfaces of a collectingmember. An area S1 of a portion of the negative electrode 7 not facing the positive electrode 6 is set to be not more than 10% of an area S2 of a portion of the negative electrode 7 facing the positive electrode 6. An influence that the portion not facing the positive electrode affects a battery reaction is controlled, and the decrease in the capacity maintenance factor or the charging/discharging efficiency according to cycling use can be depressed.