Sealing Structure of Liquid Injection Port of Battery Can, Battery Cell, Battery and Vehicle Including the Same

A structure for sealing a liquid injection port of a battery cell may include a can with one open end; an electrode assembly accommodated in the can; a cap covering the open end of the can; a liquid injection port provided at the cap; and a closing member inserted in the liquid injection port. The closing member inserted in the liquid injection port seals and is fixed to the liquid injection port through a sealing and fixing material melting at a predetermined temperature. The closing member includes a ball made of metal material. The sealing and fixing material may include a synthetic resin layer coated on the surface of the ball, or a solder filled between the surface of the ball and the inner circumferential surface of the liquid injection port with the ball inserted in the liquid injection port to seal the liquid injection port and fix the ball to the liquid injection port.