Ammonia Plasma Engineering Enables Efficient Regeneration of Spent Graphite Anodes

Abstract

Recycling spent graphite anodes is essential for the sustainable development of the lithium-ion battery (LIB) industry. Conventional recycling technologies are often constrained by inherent drawbacks, including high energy consumption, severe secondary pollution, and inadequate structural restoration. Herein, we report a simple room-temperature NH3 plasma treatment strategy for regenerating spent graphite into high-performance anodes. Through precise control of the plasma treatment conditions, three key functions are achieved simultaneously: effective removal of residual passivating solid electrolyte interphase (SEI) species, restoration of the graphitic structural ordering and in situ nitrogen doping. The optimal regenerated anode (denoted N-Gr-20), obtained by 20 min plasma treatment, delivers a high reversible specific capacity of 412 mAh g–1 at 0.5 C. It also exhibits excellent rate capability (296 mAh g–1 at 3.0 C) and exceptional long-cycle stability, retaining a capacity of 286 mAh g–1 after 350 cycles at 2.0 C. Electrochemical kinetic analyses indicate that the restored graphitic framework promotes solid-state Li+ diffusion, while nitrogen-induced surface defects provide additional active sites for surface-controlled lithium storage. Overall, this work establishes a green and sustainable closed-loop strategy for spent LIB recycling and verifies the promising application potential of plasma engineering in the regeneration of spent battery anodes.