COVER PLATE ASSEMBLY, BATTERY CELL, BATTERY MODULE, BATTERY PACK, AND APPARATUS

A cover plate assembly, a battery cell, a battery module, a battery pack and an apparatus are disclosed. The cover plate assembly includes a top cover plate, where the top cover plate is provided with an explosion-proof valve; and an insulating plate, laminated with the top cover plate, where the insulating plate includes a base portion and a thinned region located on the base portion, the thinned region is formed by thinning the base portion, and a region enclosed by boundaries of an orthographic projection of the thinned region at least partially overlaps an orthographic projection of the explosion-proof valve in a thickness direction of the cover plate assembly. The thinned region is formed by thinning the base portion.