Introduced Iron-Based Catalysts for Low-Temperature Upcycling Regeneration of Spent Graphite towards Ultra-Fast Lithium Storage Properties

Spent graphite, as the main component of retired batteries, have attracted plenty of attentions. Although a series of recycling strategies are proposed, they still suffer from high cost of regeneration and large CO₂ emission, mainly ascribed to the full-recovery of surface and internal phase at ultra-high temperature. However, the existing of suitable internal defects is conductive to their energy-storage abilities. Herein, with the introduction of Fe-based catalysts, spent graphite is successfully repaired at low temperature with the tailored surface traits, including conductivities, isotropy and so on. As Li-storage anodes, all of samples can display a capacity of 340 mAh g⁻¹ above at 1.0 C after 200 cycles. At high rate 5.0 C, their capacity can be also kept ≈300 mAh g⁻¹, and remained ≈233 mAh g⁻¹ even after 1000 cycles. Assisted by electrochemical and kinetic behaviors, their cycling traits with dynamic surface transformations are detailed explored, including activated/fading mechanism, Li-depositions forming etc. Moreover, the calculated constant time of as-optimized regenerated sample is ≈3.0 × 10⁻⁴ s, further revealing the importance of surface designing. Therefore, the work is expected to shed light on their energy-storage behaviors, and offer low-temperature regenerated strategies of spent graphite with high value.