SEPARATOR, BATTERY CELL, BATTERY AND ELECTRICAL APPARATUS

The present application relates to a separator, a battery cell, a battery and an electrical apparatus, wherein the separator comprises two surfaces opposite to each other along its own thickness direction, at least one of the surface of the separator and the interior of the separator comprises a pore structure, and the separator further comprises a swellable polymer; the separator satisfies: when a pressure of 1.25 MPa is applied along the thickness direction of the separator, the compression rate ΔV of the separator is ≤25%.