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 LiPF6, alleviate the loss of transition metal ions, maintain the integrity of crystal structure and improve the interfacial charge transfer.