Enhancing the rate performance by in situ surface engineering to form amorphous fast ion conductor Li1.5La1.5TeO6 on Ni-rich cathodes

Layered Ni-rich cathodes LiNi1-x-yCoxMnyO2 (1-x-y >= 0.6, NCM) struggle with thermal stability and capacity decline over time. Herein, we utilized the sol-gel method to in-situ coat a nanolayer of the amorphous fast ion conductor Li1.5La1.5TeO6 (LLTeO) on LiNi0.83Co0.12Mn0.05O2 (NCM83). This coating reduces lithium residues and enhance the diffusion of Li+ ion at the interface of the cathode materials, resulting in improved cycling stability and rate performance of NCM83. The Li+ diffusion coefficient increased from 8.757 x 10-12 cm2 center dot s-1 for pristine NCM83 to 2.967 x 10-11 cm2 center dot s-1 for NCM83 modified with a 5 wt% LLTeO coating (NCM83@0.05LLTeO). After 100 cycles at a discharge rate of 3 C, the discharge specific capacity of NCM-0.05LLTeO increased to 144.56 mAh center dot g-1 compared to the pristine NCM83 of 129.35 mAh center dot g-1, and the capacity retention for NCM-0.05LLTeO and the pristine NCM83 were 88.97 % and 83.22 %, respectively. This study manifests the efficacy of amorphous LLTeO coatings in surmounting the prevalent limitations of Ni-rich cathodes.