Nano-particulate surface pinning of CeO₂ enables durable high-voltage lithium-ion batteries

Abstract

Elevating the cut-off voltage of LiCoO₂ (LCO) cathode in lithium-ion batteries (LIBs) enhances capacity but increases structural instability. While surface coatings are used to mitigate structural degradation at high voltages, conventional full coverage coatings often fail to withstand the cyclic mechanical stress, resulting in crack formation and performance decay. Here, a multifunctional CeO₂ nanoparticle (NP) pinning structure is designed as a surface coating on LCO (LCO@CeO₂) to enable stable operation at a high cut-off voltage of 4.6 V (vs Li/Li⁺). This surface pinning architecture balances structural integrity with minimal inactive material usage. The CeO₂ NPs are strategically anchored to the LCO surface, creating a pinning structure that accommodates volume changes and suppresses fracture formation in the cathode. Moreover, the CeO₂-mediated fast Li⁺ transport pathways are established, improving high-rate capability. The interspersed CeO₂ NPs also act as oxygen reservoirs, stabilizing reversible (O₂)³⁻ species during high-voltage oxygen anionic redox reactions. Consequently, the optimized LCO@CeO₂ cathode achieves a capacity retention of 85.3% after 500 cycles at 1C and a high-rate capacity of 124.8 mAh g⁻¹ at 10C. This CeO₂ NP pinning structure offers a novel practical strategy for designing durable high-voltage layered cathodes.