Enhanced electrochemical performance of Li-rich cathode material for lithium-ion batteries

Lithium (Li)-rich cathodes have attracted great attention due to their high specific capacity and energy density. However, their dramatic capacity fading limits their practical application for lithium-ion batteries. Surface coating is recognized as a universal technology for improving the capacity retention of electrodes for many energy-storage applications. In this work, an aluminum fluoride (AlF₃)-coated lithium-rich cathode with a rod-shaped structure is synthesized through a hydrothermal method, followed by a chemical coprecipitation process. The aluminum fluoride protective layer provides ideal elastic buffer interspace to ameliorate the structure stability and expedite the lithium-ion (Li⁺) diffusion dynamics, ensuring excellent electrochemical performance. Thereby the as-prepared aluminum fluoride-coated electrode has a high reversible discharge capacity of 195.6 mAh/g after 130 cycles at 0.1 C, corresponding to 89.9% of its initial specific capacity. A discharge capacity of 133.4 mAh/g can be achieved even at 2 C, much higher than that of the bare lithium-rich electrode (101.5 mAh/g). These results indicate that aluminum fluoride coating is an effective strategy to improve the electrochemical performance of lithium-rich cathodes.