Needle type lithium ion battery

The utility model relates to a needle type lithium ion battery which comprises a shell, the shell comprises a side wall extending in the axial direction, a first-stage weakening area is arranged on the side wall, and the thickness of the first-stage weakening area is smaller than that of the part, outside the first-stage weakening area, of the side wall; a main notch groove is formed in the first-stage weakening area, and the thickness of the groove bottom wall of the main notch groove is smaller than that of the first-stage weakening area. One technical effect of the utility model is that theneedle type lithium ion battery with an extremely small diameter can also realize pressure relief from the notch groove area when the internal pressure of the battery is too high, so that the safetyof the needle type lithium ion battery is improved. And pressure relief can be realized under the condition that the shell generates extremely small deformation or basically has no deformation, so that the requirement on a bat