Cylindrical lithium ion battery electrolyte injection method

The invention discloses a cylindrical lithium ion battery electrolyte injection method, a cylindrical lithium ion battery comprises a cylindrical steel shell and a cap pressed and sealed at the opening part of the cylindrical steel shell, the side wall of the cylindrical steel shell is respectively provided with a liquid injection hole and an exhaust hole, and the distance between the liquid injection hole and the exhaust hole along the cylindrical steel shell is L; the exhaust hole is hermetically connected with the vacuumizing device, the liquid injection hole is hermetically connected with the electrolyte tank, the pressure of the liquid injection hole is greater than that of the exhaust hole, and the pressure difference between the liquid injection hole and the exhaust hole is P; and the relationship between the permeability K of the electrolyte and L and P is as follows: ln K = 1.032 * ln (L/P)-1.054, and the cylindrical lithium ions control the pressure difference between the liquid injection hole and t