End cap assembly, battery cell, battery, and electrical device

An end cap assembly, applicable to a battery cell, the battery cell being a lithium-ion battery cell, wherein the end cap assembly comprises:

• an end cap body;
• a pressure relief component connected to the end cap body;
• a pressure relief component connected to the end cap body, wherein a first through-hole configured to allow passage of an electrolytic solution injected to the battery cell is made on the pressure relief component, and the pressure relief component is configured to be actuated when an internal pressure of the battery cell reaches a threshold, so as to release the internal pressure of the battery cell;
• and
• a closing component detachably disposed on the pressure relief component, wherein the closing component is configured to close the first through-hole,
• wherein the pressure relief component comprises an explosion-proof valve and the first through-hole is disposed on the explosion-proof valve, the explosion-proof valve comprises:
• a first portion taking a shape of an annular structure, wherein the first portion comprises a fragile region the fragile region extends along a circumference of the explosion-proof valve and the fragile region is configured to be actuated when the internal pressure of the battery cell reaches the threshold to release the internal pressure of the battery cell;
• and
• a second portion disposed inside the first portion along a radius of the explosion-proof valve wherein a thickness of the second portion is greater than a thickness of the first portion,
• wherein the first through-hole is made in the second portion.