According to one embodiment of the present invention, a lithium ion battery having desirable safety performance is provided. The lithium ion battery includes a battery housing, a battery cover assembled to the battery housing, a pressure relief valve coupled to the battery housing and/or battery cover, and a safety device formed on the housing and/or battery cover and fixed to the pressure relief valve. The safety device includes a shielding plate facing the pressure relief valve, a side wall and an air flow channel structure. The side wall extends from the shielding plate and connects with the battery housing or the battery cover. The air flow channel structure is defined in the side wall.