Construction Of Cobalt Oxyhydroxide Nanosheets With Rich Oxygen Vacancies As High-Performance Lithium-Ion Battery Anodes

Cobalt oxyhydroxide (CoOOH) is a promising anode material for lithium-ion batteries (LIBs) due to its high electronic conductivity (5 S cm(-1)) and theoretical specific capacity (1457 mA h g(-1)). Herein, CoOOH nanosheets are successfully obtained using a facile one-pot method, and a hierarchical nanoporous structure is formed by oxidizing cobalt hydroxide (Co(OH)(2)) in NaOH and (NH4)(2)S2O8 solution. The CoOOH anode shows better electrochemical performance compared to Co(OH)(2) and Co3O4 electrodes when applied to LIBs. The hierarchical nanoporous structure and high electronic conductivity of the CoOOH anode contribute to its outstanding initial discharge capacity (1478 mA h g(-1) at 0.2 A g(-1)), high initial coulombic efficiency (ICE, 90%), and excellent cyclability (1588 mA h g(-1) after 300 cycles). Experiments and density functional theory (DFT) calculations confirmed that the high ICE and prominent rate capability (574 mA h g(-1) at 5 A g(-1)) of the nanosheets could be ascribed to the rapid and complete conversion reaction of CoOOH upon lithiation/delithiation facilitated by hydroxyl groups and oxygen vacancies. This study provides new insights into the structure-property relationship of transition-metal oxyhydroxide anode materials for LIBs.