Abstract: A structure of lithium-ion battery module comprises a battery case, containing one or more flexible packaging polymer lithium-ion battery cells, at of which top a connecting conductor is arranged to connect them in series and/or parallel to form a battery pack, positive and negative poles of the battery pack are mounted on the connecting conductor. The structure further comprises a battery cover plate welded on the open end of the battery case to package the battery pack into the battery case, and the positive and negative pole terminals of the battery module are arranged on the battery cover plate and welded to the positive and negative poles. The plate is provided with one or more through hole, through which the air in the battery case is evacuated and the inert gas is injected, after that a steel ball is clamped into each through hole to seal the battery case.