Battery cell, electrochemical device and packaging method

A battery cell comprises a shell, an electrode assembly, a tab and a bonding structure, the shell comprises a main body part and a top sealing part connected with the main body part, the electrode assembly is accommodated in the main body part, and the tab is electrically connected with the electrode assembly and partially extends out of the top sealing part; the bonding structure is at least partially arranged between the top sealing part and the tab, and the distance between the end surface of the bonding structure and the end surface of the top sealing part is 0-0.2 mm along the direction in which the tab extends out of the top sealing part; the top sealing part meets any one of the following conditions a or b: a, the top sealing part consists of an inner unsealed area and a sealing area, and the inner unsealed area is positioned on one side, close to the main body part, of the sealing area; and b, the top sealing part comprises an inner unsealed area, a sealing area and an outer unsealed area, the inner u