| CPC H01M 50/451 (2021.01) [H01M 50/426 (2021.01); H01M 50/431 (2021.01); H01M 50/491 (2021.01)] | 11 Claims |
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1. A separator for a lithium secondary battery comprising:
a porous polymer substrate; and
a porous coating layer on at least one surface of the porous polymer substrate,
wherein the porous coating layer comprises a binder and inorganic particles wherein each inorganic particles has a binding state,
wherein the binder bonds the inorganic particles to one another, wherein the inorganic particles retain their binding states, and wherein the binder bonds the inorganic particles to the porous polymer substrate and the inorganic particles retain their binding states,
the inorganic particles form interstitial volumes, wherein the inorganic particles are in contact with one another, and the interstitial volumes among the inorganic particles become vacant spaces to form pores of the porous coating layer,
the binder comprises a first binder and a second binder, the first binder having a tan δ peak at 15° C. to 27.6° C. and the second binder having a tan δ peak at 8° C. to 20.2° C., as determined by dynamic mechanical analysis (DMA) of a specimen of the first binder and a specimen of the second binder each having a thickness of 0.4 mm after pressurization at 190° C., and
the first binder is present in an amount of 5 wt % to 20 wt % and the second binder is present in an amount of 80 wt % to 95 wt %, based on 100 wt % of a combined weight of the first binder and the second binder.
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