Revealing the interfacial chemistry of silicon anodes with polysiloxane electrolyte additives

Abstract

Silicon (Si) anodes are promising in lithium-ion batteries owing to their high specific capacity and suitable voltage platform. However, particle volume expansion (>300 %) and the continuous consumption of Li+ to form new interfacial layers result in poor cycle performance. We report a sustainable low-cost Si material derived from photovoltaic cutting waste, showing a high initial Coulombic efficiency (86.9 %). The cycle stability of Si/graphite is enhanced in terms of a 38 % capacity retention increase in the presence of vinyl-terminated polydimethylsiloxane (Vi-PDMS) additive. The C = C bond in Vi-PDMS plays a role in reacting with hydrogen fluoride (HF) by-products to prevent the side reaction between HF and solvent. The decomposed macromolecule Si-containing Li salt serves as a part of the solid electrolyte interphase film and has low interface resistance. This formed interphase layer effectively mitigates stress concentration at the contact surface between silicon particles and the current collector caused by expansion forces.