Greatly recovered electrochemical performances of regenerated graphite anode enabled by an artificial PMMA solid electrolyte interphase layer

Recycling valuable elements, such as Li, Co and Ni, from spent cathode materials, is attracting considerable attention. However, the perspective on the regeneration of spent graphite (SG) anode is still being overlooked. Actually, low-cost recyclization and regeneration are highly feasible due to the intrinsic stable crystal structure of graphite. Herein, a facile sustainable way is proposed to repair the broken surface structure of SG and recover its depressed electrochemical performances. Polymethyl methacrylate (PMMA) is rationally coated onto the SG via a low-temperature polymerization as an artificial solid electrolyte interphase (SEI) layer. The study indicates that the formation of the outer natural SEI layer in the continuous lithiation/delithiation process can be effectively modulated by the inner artificial SEI, which will lead to the formation of a homogeneous bilayer structure. The bilayer SEI configuration can effectively alleviate the decomposition of electrolytes and the loss of the inventory of lithium storage, which is also supported by simulation study. The full cell constructed using regenerated graphite possesses a high capacity of 149 mAh g-1 at 1 C with a retention of 86.7% after 500 cycles. This work provides an economic strategy to regenerate spent graphite anode, paving a way for sustainable battery technology.