Enhancing the reversible capacity and cycle stability of lithium-ion batteries with Li-compensation material Li6CoO4

Abstract

High-capacity anode materials, such as SiO and Si/C, are considered promising candidates for high-energy-density lithium-ion batteries. However, the low initial Coulombic efficiency of these anode materials induced by side reactions (forming Li2O and lithium silicate) and the formation of solid electrolyte interface film reduces the active Liions and causes low-discharge capacity. Adding a Li-compensation material in the cathode or anode is an effective strategy to overcome this problem. The most used Li-compensation material is the stabilized lithium metal powder. However, this strategy has high safety risks, high costs, and is challenging to quantify. Herein, the Li-compensation material of Li6CoO4 is synthesized and investigated. The preparation conditions, stability in the air, delithiation mechanism, and structural transformation are analyzed and discussed. Electrochemical tests reveal that the discharge capacity and capacity retention of the full pouch cells (3-Ah) with Li6CoO4 additive is significantly improved. Also, the reason for such improvement is investigated. This work provides an effective strategy of Li-compensating technology to enhance the electrochemical performance of lithium-ion batteries.