Decoding High-voltage LiCoO₂: From Degradation to Stabilization Toward Durable Li-ion Batteries

Li-ion batteries (LIBs) employing the commercially established LiCoO₂ (LCO) cathode continue to dominate the market for portable electronic devices. Enhancing their volumetric energy density is crucial for extending the operational duration of advanced smart devices. One direct approach to increasing both specific capacity and energy density involves elevating the cut-off charging voltage to above 4.6 V (vs Li/Li⁺). However, high-voltage operation induces severe material degradation and battery failure, impeding further development of high-voltage LCO technologies. This review first emphasizes the growing necessity for high-voltage cathodes in contemporary LIBs, followed by a detailed exploration of the failure mechanisms of LCO at voltages up to 4.6 V. A systematic evaluation of emerging stabilization strategies is provided, covering foreign-ion (co-)doping, surface modifications, structural design, and electrolyte additives, all aimed at enhancing their structural integrity and electrochemical performance. Innovative battery design approaches and modification strategies for LCO-based full cells are also discussed. Finally, the review concludes by identifying key scientific challenges and proposing targeted research avenues to enable high-energy and durable LIBs using high-voltage LCO. This review aims to offer guiding principles with significant implications for the rational design and development of high-voltage cathode materials for advanced LIBs.