Surface Engineering Strategies of Layered LiCoO₂ Cathode Material to Realize High‐Energy and High‐Voltage Li‐Ion Cells

Abstract

Battery industries and research groups are further investigating LiCoO 2 to unravel the capacity at high‐voltages (>4.3 vs Li). The research trends are towards the surface modification of the LiCoO 2 and stabilize it structurally and chemically. In this report, the recent progress in the surface‐coating materials i.e., single‐element, binary, and ternary hybrid‐materials etc. and their coating methods are illustrated. Further, the importance of evaluating the surface‐coated LiCoO 2 in the Li‐ion full‐cell is highlighted with our recent results. Mg,P‐coated LiCoO 2 full‐cells exhibit excellent thermal stability, high‐temperature cycle and room‐temperature rate capabilities with high energy‐density of ≈1.4 W h cc −1 at 10 C and 4.35 V. Besides, pouch‐type full‐cells with high‐loading (18 mg cm −2 ) electrodes of layered‐Li(Ni,Mn)O 2 ‐coated LiCoO 2 not only deliver prolonged cycle‐life at room and elevated‐temperatures but also high energy‐density of ≈2 W h cc −1 after 100 cycles at 25 °C and 4.47 V (vs natural graphite). The post‐mortem analyses and experimental results suggest enhanced electrochemical performances are attributed to the mechanistic behaviour of hybrid surface‐coating layers that can mitigate undesirable side reactions and micro‐crack formations on the surface of LiCoO 2 at the adverse conditions. Hence, the surface‐engineering of electrode materials could be a viable path to achieve the high‐energy Li‐ion cells for future applications.