Nonaqueous secondary battery and method of producing the same

Abstract

A nonaqueous secondary battery having a negative electrode containing a silicon active material and a nonaqueous solvent containing a fluorine-containing solvent. The active material layer has a fluorine content of 5 to 30 wt % based on the silicon content after at least 100 charge/discharge cycles at a rate of 50% or more of the battery's capacity. The battery is suitably produced by a method including applying a slurry containing silicon active material particles to a current collector, electroplating the resulting coating layer using a plating bath at a pH higher than 7 to coat at least part of the surface of the particles with copper, acid washing the coating layer to make a negative electrode, assembling the negative electrode together with a positive electrode, a separator, and a nonaqueous electrolyte containing a fluorine-containing solvent into a nonaqueous secondary battery, and subjecting the battery to a first charge operation at a low rate of 0.005 to 0.03 C.

Dependencies are inferred from the claim text.