Value-added upcycling of spent low-nickel into a high-nickel layered oxide cathode via a eutectic salt system†

Despite the promising potential of recycling spent lithium-ion battery (LIB) electrode materials for sustainable development and resource reuse, conventional regeneration methods struggle to meet the increasing demand for higher-energy-density and lower-cost LIBs. In this study, utilizing a binary eutectic salt system, we present a value-added upcycling approach aimed at transforming spent low-nickel layered oxide cathode materials into high-nickel counterparts. Incorporating NiCO₃ and MnCO₃ additives, this eutectic salt system creates a lithium-rich molten environment that effectively facilitates the diffusion of both lithium ions and transition metal ions. Consequently, this upcycling strategy not only restores the layered structure of the material but also substantially enhances its capacity and cycling stability. The upcycled LiNi_0.7Co_0.1Mn_0.2 (NCM712) cathode demonstrated a high capacity of 191 mA h g⁻¹ at a current density of 0.1C. Even after 100 cycles at 0.5C, the cathode retains a substantial capacity of 164 mA h g⁻¹ with a remarkable capacity retention of 91%. Furthermore, under a high current density of 5C, the upcycled NCM712 cathode maintains a commendable capacity of 141 mA h g⁻¹. In summary, our proposed strategy offers a feasible approach to realize the value-added recycling of spent LIBs.