Stabilizing Li-rich layered oxide cathode interface by using silicon-based electrolyte additive

Abstract

In this study, we investigate the efficacy of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (ViD4) as an electrolyte additive to enhance the electrochemical stability of Li-rich (LRO)/Li cells. The LRO/Li cell in the 1 vol% ViD4 electrolyte displays a mere 27.9 % capacity loss after 100 cycles at 0.5C (1C = 300 mAh−1), in comparison with the 66 % observed in the baseline electrolyte. Theoretical calculations reveal that ViD4 possesses a lower calculated oxidation potential than the electrolyte solution, signifying its preferential oxidation propensity. Physical characterization results demonstrate the formation of a uniform ViD4-derived film spanning 2–3 nm on the LRO cathode surface. This film enhances the stability of the cathode/electrolyte interface and safeguards the structural integrity of LRO. Moreover, ViD4 acts as a scavenger for hydrogen fluoride (HF), which is a decomposition product of LiPF6. Theoretical calculations verify the feasibility of ViD4 in effectively eliminating HF.