Abstract: This application provides a battery cell, a battery, and an electric apparatus. The battery cell includes: an electrode assembly, including a body portion and a first tab. A first size L1 of the body portion in a length direction thereof is greater than a second size L2 of the body portion in a width direction thereof. The first tab is located on at least one end of the body portion in the width direction. The first tab has a third size L3 in the length direction. The first size L1, the second size L2, and the third size L3 satisfy 0.5L2?L3?L1. The battery cell according to an embodiment of this application is intended to resolve a technical problem of severe heat generation by a tab.

Abstract: The embodiments of the application provide a battery cell and a manufacturing method and system therefor, a battery and an electric device. An end cover assembly includes: a battery box including a first wall and a pressure relief mechanism; and a protective member positioned on an outer side of the first wall and including a body portion, a shielding portion and a weak portion. The shielding portion can block emissions released from other battery cells, so as to reduce risk of melt-through of the pressure relief mechanism caused by the emissions. When thermal runaway occurs in the battery cell, the weak portion is broken under the action of a high-temperature and high-pressure substance, such that the high-temperature and high-pressure substance are discharged in time.