Surface-Modified Lithium Cobalt Oxide (LiCoO<sub>2</sub>) with Enhanced Performance at Higher Rates through Li-Vacancy Ordering in the Monoclinic Phase
Govind Kumar Mishra, Manoj Gautam, Supriya Sau, Sagar Mitra
Abstract
Lithium cobalt oxide (LCO) is yet a preferred choice because of its unique structure and electrochemical relationship. However, LCO sacrifices its structural stability and associated battery safety at higher voltage and a high rate of operation in current battery technology. To mitigate such problems, a targeted strategy has been adopted with a thin lithium cobalt manganese oxide (LiCo0.5Mn1.5O4, LCMO) coating on the LCO cathode by easy and inexpensive microwave-assisted synthesis. The as-prepared cathode structure showed a tiny amount of manganese(III) ion (Mn3+) diffusion into the bulk of LCO, which resulted in the increase of its lattice parameter and favoring the Li-ion diffusion in LCO cathode and enables a faster cycling rate 3C (20 min charging–discharging) for longer periods of time. The structural entropy estimation has been utilized to evaluate the arrangement of Li ions and the vacancy in the LCO lattice at different states of charge to investigate the stability of coated LCO at higher voltage. A comprehensive study at higher rate capability at 3C, 5C (12 min), and even at 10C (6 min) current rates and stability at a higher cutoff voltage for modified LCO has been reported here. Finally, the current study is ended with full-cell fabrication with silicon-carbon anodes and LCMO-coated-LCO cathodes in two-layer pouch-type cell format (∼15 mAh capacity) and displayed a commercial feasibility.