Patent ID: 7867649

Claim:
A non-aqueous electrolyte secondary cell comprising: a cathode comprising a lithium-containing cathode active material; an anode comprising an anode active material capable of doping and undoping lithium; a non-aqueous electrolyte; and a separator comprising a plurality of layers of a microporous polyolefine material, wherein, at least two microporous polyolefine material layers have different porosity values and include a highest porosity layer proximate to the anode and a lowest porosity layer proximate to the cathode during discharge of the cell, the highest porosity layer has an average pore diameter of 0.1 μm to 1.0 μm and a porosity value B of 45%, the lowest porosity layer has a thickness of 2% to 55% of the separator thickness, an average pore diameter of 0.03 μm to 0.2 μm, and a porosity value A of 25% a porosity ratio A/B is 44% to 93%, and at least one microporous material layer is of a resin coating material on one of the plurality of layers that has dried in situ.