Battery cell, battery, and electrical device

A battery cell, comprising:

• an electrode assembly;
• a shell for accommodating the electrode assembly and including a first side plate;
• a pressure relief mechanism provided on the first side plate, the pressure relief mechanism being configured to be actuated when an internal pressure of the battery cell reaches a first threshold, so as to release the internal pressure;
• and
• a support plate arranged between the first side plate and the electrode assembly, wherein the support plate is provided with a weak portion which is opposite to the pressure relief mechanism in a thickness direction of the first side plate, a shape of the weak portion is the same as that of an outline of the pressure relief mechanism, an external dimension of the weak portion is not larger than the dimension of the outline of the pressure relief mechanism, and the support plate is configured to rupture along the weak portion when the internal pressure of the battery cell reaches a second threshold, so as to form a channel for guiding fluid to the pressure relief mechanism;
• wherein the support plate includes a first portion, a second portion and a first weak portion, the first portion is arranged opposite to the pressure relief mechanism, the second portion surrounds an outside of the first portion, and the first weak portion is connected between the first portion and the second portion;
• and
• wherein the support plate includes a plurality of first through holes spaced along a circumference of the first portion, and the first through hole penetrates through the support plate along the thickness direction of the first side plate;
• a first connecting section exists between two adjacent first through holes, a plurality of first connecting sections and a plurality of first through holes are alternately arranged along the circumference of the first portion and form the first weak portion.