Recycling\nSpent LiCoO<sub>2</sub> for Improved 4.6\nV Performance

Rapid replacement of “3C” (computer, communication,\nand consumer electronics) products and the limited calendar life of\nbatteries lead to the increasing retirement of LiCoO<sub>2</sub> (LCO)-based\nlithium-ion batteries (LIBs), which makes recycling in high demand\nfor a sustainable development. Herein, we propose a straightforward\nsintering process to rejuvenate the spent LCO to achieve a much-favored\ncycling stability at 4.6 V. The addition of Mg<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> is critical for restoring the structure of spent\nLCO after heat treatment, enabling a synergistic effect of bulk Mg<sup>2+</sup> doping and surface Li<sub>3</sub>PO<sub>4</sub> decoration\nin the reconstructed LCO. This structural modification effectively\nsuppresses harmful O3/H1–3 phase transitions and enhances Li<sup>+</sup> transport dynamics, thereby endowing the recycled LCO with\nextraordinary cycling stability and rate performance. In the 4.5 V\nLCO/graphite pouch cell, a capacity retention of 75% is achieved after\n480 cycles. Our work provides an efficient route for recycling and\nreusing spent LCO cathode materials, showing promise for practical\napplications.