Effects of Single-Element Doping on the Structural Evolution and High-Voltage Performance of O2-Type LiCoO2

Yilong Han; Jintao Zhang; Sheng Liu

Abstract

O2-type lithium cobalt oxide (LiCoO₂, O2-LCO), featuring a unique ABAC oxygen stacking sequence and enhanced structural reversibility at high voltages, has garnered significant attention in recent years. However, its structural stability and interfacial compatibility during long-term cycling under high-voltage operation remain critical challenges. In this work, Al-, Mg-, Nb-, and B-doped O2-LCO cathode materials with the nominal composition (LiCo_0.99M_0.01O₂, M = Al, Mg, Nb, B) were synthesized via an ion-exchange method. The effects of different dopants on crystal structure, phase-transition behavior, and electrochemical performance of O2-LCO were systematically investigated. The results demonstrate that dopants play critical roles in regulating the structural evolution and cycling stability of O2-LCO. This comparative study provides fundamental insights into dopant-dependent structural evolution and offers guidance for the rational design of high-voltage, high-energy-density layered cathode materials.

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