Structural Understanding for High-Voltage Stabilization of Lithium Cobalt Oxide

The rapid development of modern consumer electronics is placing higher demands on the lithium cobalt oxide (LiCoO2; LCO) cathode that powers them. Increasing operating voltage is exclusively effective in boosting LCO capacity and energy density but is inhibited by the innate high-voltage instability of the LCO structure that serves as the foundation and determinant of its electrochemical behavior in lithium-ion batteries. This has stimulated extensive research on LCO structural stabilization. Here, it is focused on the fundamental structural understanding of LCO cathode from long-term studies. Multi-scale structures concerning LCO bulk and surface and various structural issues along with their origins and corresponding stabilization strategies with specific mechanisms are uncovered and elucidated at length, which will certainly deepen and advance the knowledge of LCO structure and further its inherent relationship with electrochemical performance. Based on these understandings, remaining questions and opportunities for future stabilization of the LCO structure are also emphasized. Structural instability is the major factor limiting access to higher capacity and energy density of the monopoly LiCoO2 cathode in consumer electronics. This necessitates in-depth and thorough knowledge of the LiCoO2 structure. The present review focuses on the fundamental structural understanding of LiCoO2 and aims to establish a deeper structure-performance relationship to better guide future structural stabilization.image