The utility model discloses a top cover, a cap and a structure capable of losing stability through
battery cell heat for a cylindrical
lithium ion battery, the top cover comprises a top cover body, the top cover body comprises an annular part, a
central pressure relief hole and a convex shielding part, and the convex shielding part comprises an inclined support leg part and a flat top shielding part; the inclined supporting leg parts incline in the direction away from the annular part, and the top ends of the inclined supporting leg parts are connected with the flat-top shielding part. A
thinning structure is arranged on the inner wall of the joint of the inclined supporting leg part and the flat-top shielding part; the edge, located between every two adjacent inclined supporting leg parts, of the flat-top shielding part is a straight line edge. A pressure relief channel is formed by the straight line edge, the corresponding part, exposed out of the flat-top shielding part, of the
central pressure relief hole and the two inclined supporting leg parts; the cap comprises a top cover, an anti-explosion piece, a connecting piece, an isolation ring and a sealing ring. According to the utility model, the edge of the flat-top shielding part is adjusted to be the linear edge, the area of the pressure relief channel is increased compared with the traditional arc-shaped edge, the
thinning structure is arranged at the joint of the flat-top shielding part and the inclined supporting leg part, so that the flat-top shielding part is easier to break, the pressure relief speed is increased, the pressure relief time is advanced, and the thickness of the steel shell is increased, so that the steel shell can bear higher pressure; the battery adopting the structure provided by the utility model can safely pass through the
thermal instability test, and the passing rate is high.