Sustainable Recovery and Reuse of Hard Carbon From Scrap and End-of-Life Sodium-Ion Batteries

Abstract

As Sodium-ion battery (SIB) technology progresses toward commercial viability, sustainable end-of-life (EOL) management is critical. Methods for recycling key components such as hard carbon (HC), a negative electrode material, remain underexplored. This study introduces a direct and efficient recycling approach for HC from production scrap and EOL cells using “ice-stripping” followed by a low-temperature binder negation at 300 °C under nitrogen. The effects of temperature on HC structural integrity and electrochemical performance are comprehensively characterized using XRD, Wide-Angle X-ray Scattering (WAXS), and XPS. Heating above 400 °C induces irreversible damage to HC's graphene layers and modifies the carbon surfaces, resulting in poor electrochemical performance. However, HC reclaimed at 300 °C retains near-pristine electrochemical performance, with capacities of 243 mAh g⁻¹ (scrap) and 228 mAh g⁻¹ (EOL) after 50 cycles. Full-cell configurations demonstrates robust cycling stability, with 86% and 89% capacity retention after 200 cycles for HC derived from scrap and EOL cells, respectively. This work highlights the potential of lower-temperature, direct recycling to enable a circular economy for SIBs. The findings set a benchmark for developing sustainable recycling methods for HC and other SIB components.