Method for improving capacity grading capacity of lithium ion battery cell

The invention discloses a method for improving the capacity grading capacity of a lithium ion battery cell, which comprises the following steps: the battery cell enters a formation stage after liquid injection and standing, after the multi-stage charging process in the existing formation stage is finished, the multi-stage charging is continued at 0.2 C-0. 4C current, after the required SOC is reached, the 0.2 C-0. 4C constant current discharge is adopted, and then standing is carried out; and after entering the capacity grading stage, standing and first-stage constant current charging, increasing the current to carry out second-stage constant current charging, reducing the current to carry out third-stage constant current charging, and then continuing the normal flow of the capacity grading stage. According to the method, the productivity efficiency and the capacity requirement are organically combined, the process time is shortened, the productivity efficiency is improved, the time required by formation and