Liquid injection method for lithium-supplementing battery cell and electrolyte for lithium-supplementing battery cell

The invention relates to the technical field of lithium ion battery cells, in particular to a liquid injection method for a lithium supplementing battery cell and an electrolyte for the lithium supplementing battery cell. The liquid injection method comprises the following steps: providing a battery cell with a lithium-supplementing negative electrode; the method comprises the following steps: performing primary liquid injection on a battery cell by adopting first electrolyte; carrying out secondary liquid injection on the battery cell by adopting a second electrolyte; wherein the first electrolyte comprises a first solvent, a first lithium salt and a diluent, the first electrolyte is a high-concentration electrolyte with the lithium salt concentration larger than that of the second electrolyte, and the molar ratio of the first solvent to the first lithium salt is smaller than or equal to 4. According to the technical scheme provided by the invention, the problem of side reaction between the electrolyte with