An end cap assembly includes an end cap configured to close a housing of a battery cell, an adapting member configured to electrically connect an electrode assembly of the battery cell to an electrode terminal of the battery cell, and a supporting member between the adapting member and the end cap. An explosion-proof mechanism provided at the end cap is configured to be actuated to release an internal pressure of the battery cell when thermal runaway occurs in the battery cell. The supporting member is made of a high-temperature-resistant material. An orthographic projection of the adapting member on a first surface of the end cap at least partially overlaps an orthographic projection of the explosion-proof mechanism on the first surface of the end cap and an orthographic projection of the supporting member on the first surface. The first surface is a surface of the end cap facing the housing.