The present invention relates to the field of battery technology, and discloses a battery and a
battery pack, including: a shell, at least one end of which is open; a cover plate, which is arranged corresponding to the opening to block the opening, the shell and the cover plate are enclosed to form a storage space, the cover plate is welded to the shell to form a connecting section weld and a
bursting section weld, the connecting section weld and the
bursting section weld are connected end to end along the circumference of the cover plate; the fusion depth of the connecting section weld is greater than the fusion depth of the
bursting section weld, and / or, the
fusion width of the connecting section weld is greater than the
fusion width of the bursting section weld; a pole group is arranged in the storage space. In the present invention, when the battery is out of control, the cover plate can explode in the bursting section weld area, thereby quickly tearing the entire bursting section weld, and at the same time, the cover plate and the shell are kept connected at the connecting section weld, so that the cover plate can be completely flipped open, increasing the exhaust port area of the battery, effectively alleviating battery out of control, and improving the safety of battery use.