Hybrid Surface Modification and Bulk Doping Enable Spent LiCoO<sub>2</sub> Cathodes for High-Voltage Operation.

Liu, Zhenzhen; Han, Miaomiao; Zhang, Shengbo; Li, Huaimeng; Wu, Xi; Fu, Zhen; Zhang, Haimin; Wang, Guozhong et al. · Adv Mater · 2024

basic_science · Level V

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Abstract

The emerging market demand for high-energy-density of energy storage devices is pushing the disposal of end-of-life LiCoO<sub>2</sub> (LCO) to shift toward sustainable upgrading into structurally stable high-voltage cathode materials. Herein, an integrated bulk and surface commodification strategy is proposed to render spent LCO (S-LCO) to operate at high voltages, involving bulk Mn doping, near surface P gradient doping, and Li<sub>3</sub>PO<sub>4</sub>/CoP (LPO/CP) coating on the LCO surface to yield upcycled LCO (defined as MP-LCO@LPO/CP). Benefiting from hybrid surface coating with Li<sup>+</sup>-conductive Li<sub>3</sub>PO<sub>4</sub> (LPO) and electron conductive CoP (CP) coupled with Mn and P co-doping, the optimized MP-LCO@LPO/CP cathode exhibits enhanced high-voltage performance, delivering an initial discharge capacity of 218.8 mAh g<sup>-1</sup> at 0.2 C with excellent capacity retention of 80.9% (0.5 C) after 200 cycles at a cut-off voltage of 4.6 V, along with 96.3% of capacity retention over 100 cycles at 4.5 V. These findings may afford meaningful construction for the upcycling of commercial S-LCO into next-generation upmarket cathode materials through the elaborate surface and bulk modification design.