Patent ID: 8192859

Claim:
A secondary battery comprising: a positive electrode; a negative electrode containing a metal compound having a lithium ion absorption potential of 0.2V (vs.Li/Li + ) or more; a separator which is provided between the positive electrode and the negative electrode, comprises cellulose fibers and pores having a specific surface area of 5 to 15 m 2 /g, and has a porosity of 55 to 80% and at least a bimodal pore diameter distribution having a first peak in a pore diameter range satisfying 0.2≦D<2, where D is a pore diameter (μm) and a second peak in a pore diameter range of 2 to 30μm, wherein the specific surface area, the porosity and the pore diameter distribution are measured by mercury porosimetry; and a nonaqueous electrolyte.