Adjusting the solvation structure with tris(trimethylsilyl)borate additive to improve the performance of LNCM half cells

Abstract

Tris(trimethylsilyl)borate (TMSB) has been intensively studied to improve the performances of lithium-ion batteries. However, it is still an interesting issue needed to be resolved for the research on the Li+ solvation structure affected by TMSB additive. Herein, the electrochemical tests, quantum chemistry calculations, potential-resolved in-situ electrochemical impedance spectroscopy measurements and surface analyses were used to explore the effects of Li+ solvation structure with TMSB additive on the formation of the cathode electrolyte interface (CEI) film in LiNi0.8Co0.1Mn0.1O2/Li half cells. The results reveal that the TMSB additive is easy to complex with Li+ ion, thus weaken the intermolecular force between Li+ ions and ethylene carbonate solvent, which is benefit for the cycle performance. Besides, the changed Li+ solvation structure results in a thin and dense CEI film containing compounds with Si–O and B–O bonds which is favorable to the transfer of Li+ ions. As a result, the performances of the LNCM811/Li half cells are effectively improved. This research provides a new idea to construct a high-performance CEI film by adjusting the Li+ solvation structures.