Residual fluoride self-activated effect enabling upgraded utilization of recycled graphite anode

Recycling graphite anode from spent lithium-ion batteries (SLIBs) is regarded as a crucial approach to promoting sustainable energy storage industry. However, the recycled graphite (RG) generally presents degraded structure and performance. Herein, the residual fluoride self-activated effect is proposed for the upgraded utilization of RG. Simple and low-energy water immersion treatment not only widens the interlayer spacing, but also retains appropriate fluoride on the surface of RG. Theoretical analysis and experiments demonstrate that the residual fluoride can optimize Li+ migration and deposition kinetics, resulting in better Li+ intercalation/deintercalation in the interlayer and more stable Li metal plating/stripping on the surface of RG. As a result, the designed LFP||RG full cells achieve ultrahigh reversibility (∼100% Coulombic efficiency), high capacity retention (67% after 200 cycles, 0.85 N/P ratio), and commendable adaptability (stable cycling without short-circuiting, 0.15 N/P ratio). The energy density is improved from 334 Wh kg−1 of 1.1 N/P ratio to 367 Wh kg−1 of 0.85 N/P ratio (total mass based on cathode and anode). The exploration of RG by residual fluoride self-activated effect achieves upgraded utilization beyond fresh commercial graphite and highlights a new strategy for efficient reuse of SLIBs.