There is no specific limitation on the composition of the separator in the present disclosure. It may be a separator commonly used in the art. For example, the separator may be a porous membrane made of polyolefins such as polytetrafluoroethylene, polypropylene or polyethylene.

The electrolyte may be various conventional electrolytes, such as non-aqueous electrolyte. The non-aqueous electrolyte is a solution formed by an electrolyte lithium salt in a non-aqueous solvent. Any traditional non-aqueous electrolyte known to those persons skilled in the art may be used. For example, the electrolyte may be at least one selected from a group consisting of lithium hexafluorophosphate (LiPF₆), lithium perchlorate (LiClO₄), lithium tetrafluoroborate (LiBF₄), lithium hexafluoroarsenate (LiAsF₆) and lithium hexafluorosilicate (LiSiF₆). The non-aqueous solvent may be selected from a group consisting of linear esters, cyclic esters and mixtures thereof. The linear esters may be at least one selected from a group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC) and dipropyl carbonate (DPC). The cyclic esters may be at least one selected from a group consisting of ethylene carbonate (EC), propylene carbonate (PC) and vinylene carbonate (VC).

The features and advantages of the present invention are apparent from the following examples. The examples are intended to illustrate and not to limit the invention in any way.

Testing.

1. Testing for BET specific surface area and pore size.