Constructing a stable interface by 2,4,6-trimethoxyboroxine as an electrolyte additive for Li-rich layered oxide cathode under high voltage

Li-rich layered oxides (LLO) feature high delivery capacity are considered the most promising cathodes for the next-generation high-energy–density battery systems. Unfortunately, the LLO cathode suffers from poor cycling stability and fast voltage fading because of structural failure and unstable electrode/electrolyte interphase. Herein, we propose 2,4,6-trimethoxyboroxine (TMBX) as an effective electrolyte additive for enhancing the specific capacity and service life of LLO cathode. Impressively, the LLO/Li cell with 1 wt% TMBX exhibits a specific capacity of 226.3 mAh/g with a considerable cycling retention of 96.1% at 0.5 C after 200 cycles, while the capacity of the baseline cell is only 133.8 mAh/g and the cycling retention is less than 60%. Even at 1 C, the cell using TMBX additive still sustains a capacity retention of as high as 91.1% after 400 cycles. The cell with excellent performance is attributed to TMBX additive which can form a uniform, robust, and boron-rich interface film on both the cathode and anode surfaces simultaneously. Structural characterization and mechanism analysis reveal that TMBX additive can effectively eliminate HF hydrolysis from LiPF 6 , alleviate the loss of transition metal ions, maintain the integrity of crystal structure and improve the interfacial charge transfer.