METHOD OF PRODUCING LITHIUM ION SECONDARY BATTERY AND NEGATIVE ELECTRODE MATERIAL

A method of producing a lithium ion secondary battery includes preparing an electrode body which includes a positive electrode and a negative electrode and in which the negative electrode contains a negative electrode material containing a porous graphite particle having open pores and SiOdisposed in the open pores, producing a battery assembly including the electrode body and a non-aqueous electrolytic solution containing LiPFwith a concentration of mol/L or more, and generating lithium difluorophosphate in the electrode body