| 摘要 |
PROBLEM TO BE SOLVED: To provide: a separator high in liquid absorption and ion conductivity, and low in thermal shrinkage; and a lithium ion secondary battery excellent in cycle characteristic at a room temperature and dischargeability under a low-temperature environment, and rate characteristic and having safety.SOLUTION: A separator comprises: a microporous film having fine pores; and a coating layer provided on a surface of the microporous film. The coating layer includes polymer particles and binder particles. The polymer particles each have a hollow structure including a shell and a cavity located in the shell. The shell has nano pores distributed in its outer surface and communicating with the cavity. The polymer particles have a particle size larger than the pore size of the fine pores in the microporous film. The binder particles have a particle size larger than the pore size of the fine pores in the microporous film. The microporous film has a thickness of 3-35 μm, and the coating layer has a thickness of 0.5-6 μm. A lithium ion secondary battery comprises: a positive electrode sheet; a negative electrode sheet; a separator interposed between the positive and negative electrode sheets; and an electrolyte. |
