Structure for Sealing Liquid Injection Port of Battery Can, Battery Cell Employing the Same, Battery Pack Including the Battery Cell, and Vehicle Equipped with the Battery Pack

A method of manufacturing a battery cell, the method comprising:

• a battery can preparation step of preparing a battery can having a sidewall portion, a bottom portion connected to a first axial end of the sidewall portion and an open end provided at a second axial end of the sidewall portion, and sealing and insulating a first electrode terminal in a center of the bottom portion;
• an electrode assembly preparation step of preparing an electrode assembly comprising a first electrode and a second electrode, wherein a tab of the first electrode and a tab of the second electrode are disposed at opposite sides of the electrode assembly in an axial direction,
• a cap preparation step of preparing a liquid injection port and a cap with a first chrome-coated layer around the liquid injection port;
• a stopper preparation step of preparing a stopper with a second chrome-coated layer;
• a first electrode terminal connecting step of accommodating the electrode assembly in the battery can such that the tab of the first electrode faces the bottom portion of the battery can after the battery can preparation step and the electrode assembly preparation step, and connecting the tab of the first electrode and the first electrode terminal;
• a second electrode connecting step of connecting the cap to the tab of the second electrode after the electrode assembly preparation step and the cap preparation step;
• a cap fixing step of fixing the cap to the battery can after the first electrode terminal connecting step;
• a liquid injection step of injecting an electrolyte solution into the battery can after the first electrode terminal connecting step, the second electrode connecting step, and the cap fixation step;
• and
• a liquid injection port closing step of closing the liquid injection port with the stopper by heating a heat-fusion layer interposed between the first chrome-coated layer and the second chrome-coated layer, the heat-fusion layer containing polypropylene-maleic anhydride to form a heat-fused portion after the liquid injection step and the stopper preparation step.