Ball‐Milling Synthesis of Richly Oxygenated Graphene‐Like Nanoplatelets from used Lithium Ion Batteries and Its Application for High Performance Sodium Ion Battery Anode

Abstract The exploration of waste graphite from used lithium ion batteries (LIBs) and its derivatives for versatile applications is an efficient route to promote the environmental and eco‐friendly recycling of used LIBs. Sodium ion batteries (SIBs) are alternative candidates to LIBs mainly due to similar electrochemical mechanism of SIBs to LIBs and rich natural resource of Na. Herein, a holey waste graphite (hG_w) with well‐defined porous structure is produced by the annealing of lithiated waste graphite (Li/G_w) from used LIBs under a flow gas of H₂O and subsequent lithium leaching in DI water. Benefiting from the holey structure of hG_w, holey graphene nanoplatelets (hGn_w) with ultrahigh‐level edge‐grafted oxygen groups (≈37.8 at%) are synthesized by mechanical balling of hG_w. As anode for SIBs, the hGn_w present outstanding sodium ion storage properties with high initial Coulombic efficiency of 82.4%, high reversible capacity (e.g., 416.1 mAh g⁻¹ at 0.03 A g⁻¹), excellent rate capability (e.g., 153.3 mAh g⁻¹ at 2 A g⁻¹), and long‐term cycling stability (e.g., 152.7 mAh g⁻¹ after 400 cycles at 1.5 A g⁻¹).