Trimethoxyboroxine as an electrolyte additive to enhance the 4.5 ​V cycling performance of a Ni-rich layered oxide cathode

Ni-rich layered oxides are attractive cathode materials for advanced lithium-ion batteries (LIBs) due to their high energy density. However, their large-scale application is seriously hindered by their interfacial instability, especially at a high cut-off potential. Here, we demonstrate that trimethoxyboroxine (TMOBX) is an effective film-forming additive to address the interfacial instability of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) material at a high cut-off voltage of 4.5 ​V. We find that TMOBX decomposes before carbonate solvent and forms a thin cathode electrolyte interphase (CEI) layer on the surface of the NCM811 material. This TMOBX-formed CEI significantly suppresses electrolyte decomposition at a high potential and inhibits the dissolution of transition metals from NCM811 during cycling. In addition, electron-deficient borate compounds coordinate with anions ( P F 6 − , F − , etc.) and H 2 O in the battery, further improving the battery's stability. As a result, adding 1.0 ​wt% of TMOBX boosts the capacity retention of a Li||NCM811 ​cell from 68.72% to 86.60% after 200 cycles at 0.5C in the range of 2.8–4.5 ​V.