Secondary battery

A secondary battery comprising an electrode structure, the electrode structure comprising:

• a separator having one surface and an other surface;
• a positive electrode changing in volume by expansion during discharging and contraction during charging, the positive electrode being provided on the one surface of the separator;
• and
• a negative electrode changing in volume by contraction during discharging and expansion during charging, the negative electrode being provided on the other surface of the separator, wherein
• each of a volume ratio of the positive electrode and a volume ratio of the negative electrode is 1.1 or more, the volume ratio of the positive electrode being a value obtained by dividing a volume of the positive electrode under expansion by a volume of the positive electrode under contraction and the volume ratio of the negative electrode being a value obtained by dividing a volume of the negative electrode under expansion by a volume of the negative electrode under contraction,
• at least one of the volume ratio of the positive electrode and the volume ratio of the negative electrode is 1.9 or more, and
• a total volume ratio is 1.2 or less, the total volume ratio being a value obtained by dividing a larger value by a smaller value with respect to a total volume of a volume of the positive electrode and a volume of the negative electrode in a discharged state and a total volume of a volume of the positive electrode and a volume of the negative electrode in a charged state.