Ferrocene-catalyzed low-temperature graphitization for green regeneration of spent graphite anodes in lithium-ion batteries

Abstract

Graphite, as a non-renewable key anode material in lithium-ion batteries, requires efficient and green regeneration to ensure the sustainable development of the battery industry. Conventional recycling methods are hindered by the reliance on highly corrosive reagents or ultra-high temperatures, leading to significant environmental impacts. This study proposes a low-temperature graphitization repair strategy based on ferrocene catalysis. Through iron-based catalyst-promoted carbon layer ordering under mild conditions at 700 °C, the graphitization degree and interlayer structural integrity of the material are significantly enhanced. The regenerated graphite (R-Gra) exhibits excellent electrochemical performance, delivering an initial charge capacity of 359.8 mAh g⁻¹ at 0.05C, comparable to commercial materials, and retaining 222.7 mAh g⁻¹ at a high rate of 3C, with improved cycling stability. Systematic structural characterization and kinetic analysis reveal the intrinsic relationship between the catalytic graphitization process and the restoration of electrochemical properties. Furthermore, tracking the migration behavior of Fe species during long-term cycling confirms that Fe/Fe₃C nanoparticles remain stably encapsulated within the graphite interlayers, without significant dissolution or migration, effectively avoiding side reactions and electrode interface contamination. This work provides an effective low-temperature and green regeneration route for spent graphite anodes, demonstrating both environmental and practical feasibility.