Surface engineering strategies of layered LiCoO2 cathode material to realize high-energy and high-voltage li-ion cells
Battery industries and research groups are further investigating LiCoO2 to unravel the capacity at high-voltages (>4.3 vs Li). The research trends are towards the surface modification of the LiCoO2 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 LiCoO2 in the Li-ion full-cell is highlighted with our recent results. Mg,P-coated LiCoO2 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)O2 -coated LiCoO2 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 LiCoO2 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.