Thermal Safety Evaluation of Silane Polymer Compounds as Electrolyte Additives for Silicon-Based Anode Lithium-Ion Batteries

Abstract

The capacity fading and thermal safety issues caused by the volume effect of Si-based anodes and unstable solid electrolyte interphase (SEI) films during long-term cycling limit its large-scale application. In this study, silane polymer compound (2-cyanoethyl) triethoxysilane (TCN) was selected as an electrolyte additive to improve the reversibility and thermal safety of Si-based anode lithium-ion batteries (LIBs). TCN prevented the thermal interaction between the vitiated anode and electrolyte, and the onset temperature of the thermal reaction increased from 122.22 to 127.07 °C, as demonstrated by the results of thermogravimetric analysis and differential scanning calorimetry. The thermal stability of lithiated anodes containing various electrolytes was then assessed using a range of thermo-kinetic models. The results revealed that the activation energy of Si-based lithiated anodes increased from 68.46 to 91.32 kJ/mol, while the thermal hazard greatly decreased. Additionally, the electrochemical test and characterization results showed that TCN helped generate a stable SEI coating with more Li2CO3 components, which improved the cells’ cycle stability. This study provides a new reference for the growth of LIBs with high security and energy density.