trolyte dissolved in the nonaqueous solvent is preferred to be 0.5 to 2.5 mol/L. [0093] When using a liquid nonaqueous electrolyte layer, a nonaqueous electrolyte layer can be formed by impregnating and holding the liquid nonaqueous electrolyte in the separator. [0094] As the separator, various materials can be used, such as a porous film containing polyethylene, polypropylene, or polyvinylidene f