Cover plate, cover plate assembly, battery housing, battery module, and battery pack

A cover plate assembly comprising an insulating plate, a sealing structure, and a cover plate, wherein the insulating plate is provided with a through hole, and the cover plate comprises:

• a body portion, wherein a side of the body portion is configured to connect the insulating plate, and the body portion has a thickness D1, wherein 0.8 mm≤D1≤1.5 mm;
• and
• a first boss protruding from a side of the body portion away from the insulating plate, wherein the first boss is provided with a liquid injection hole communicating with the through hole;
• wherein the body portion comprises a setting surface facing the insulating plate, and the setting surface is provided with a first concavity corresponding to the first boss;
• the cover plate has a thickness D2 at the first boss, wherein 0.8 mm≤D2≤1.5 mm;
• and
• the sealing structure is configurated to seal the liquid injection hole and partially penetrate through the through hole.