Surface-interspersed nanoparticles induced cathode-electrolyte interphase enabling stable cycling of high-voltage LiCoO2

Abstract

The development of high-voltage LiCoO2 (LCO) is crucial for achieving lithium-ion batteries with a high volumetric energy density. However, LCO experiences accelerated degradation at high voltages due to severe interface and structure instability. A uniform and robust cathode-electrolyte interphase (CEI) serves as a vital barrier for protecting the interface. However, the smooth surface of single-crystalline LCO, lacking grain boundaries, poses challenges in generating an effective CEI. Herein, ZrO2 nano-rivets are constructed on the surface of LCO to provide phase boundaries for preferential film-forming sites, inducing the formation of a uniform and robust CEI. The high-quality CEI derived from ZrO2 nano rivets stabilizes the fragile surface of high-voltage LCO and facilitates lithium-ion diffusion. In addition, a Zr diffusion layer is simultaneously built in the LCO bulk. Zr diffusion into the LCO lattice not only effectively suppresses unfavorable phase transitions to stabilize the bulk structure, but also mitigates oxygen charge deficiencies at the highly delithiated state, therefore stabilizing lattice oxygen. Consequently, the modified LCO exhibits excellent capacity retention of 80% after 700 cycles at 4.6 V. This work emphasizes the significance of material surface properties in CEI formation and provides new insights for the design of CEI.