Promoting air stability of Co-Li2O cathode additive via LiAlO2 coating for lithium-ion batteries

Abstract

The consumption of Li⁺ in anode or cathode side results in low coulombic efficiency and poor cycling stability. Prelithiation additive is considered as an effective way to offset the irreversible Li⁺ loss, especially the one with high irreversible specific capacity and suitable working voltage. Li₂O exhibits one of the most promising candidates, benefiting from its high theoretical specific capacity (1793 mAh g⁻¹) and adoptable working voltage. However, the sluggish Li⁺ deintercalation kinetics and inferior air stability restricts its further application. Herein, LiAlO₂ coated additives (Co-Li₂O@LAO) was prepared to alleviate the above inferior effects which Co element activated Li₂O and LiAlO₂ coating contributed to a stable interface. The as-prepared Co-Li₂O@ LAO additives showed a specific capacity as high as 813.0 mAh g⁻¹ and the initial coulombic efficiency was only 2.5 % in Li-half cells, well manifesting the prelithiation additives characteristics. Especially, the specific capacity of Co-Li₂O@ LiAlO₂ maintained at 746.4 mAh g⁻¹ even after being exposed into air for 24 h. As a comparison, the value of Co-Li₂O-24 sample was only 471.8 mAh g⁻¹. This work provides a new idea for air stable prelithiation additives preparation when it comes to the practical application.