Dual-functional trisiloxane as binder additive for high volume expansion Li-ion battery electrodes

Abstract

Silicon-based anodes for lithium-ion batteries have the inherent advantage of higher capacity. However, the inherent expansion of Si within the anodes during cycling, causing low battery life, has limited its application. Various approaches are being investigated to mitigate the adverse effects, ranging from the patterned deposition of Si, blending silicon materials with graphite active materials, and using modified polymeric binders. Inspired by the super spreading capabilities of siloxane compounds and with an aim to optimize the graphite-SiO composite electrode, this work focuses on tweaking the binder formulation with a trisiloxane-based additive which enables uniform dispersion of active material within the electrode and enhances the wetting of the electrolyte within the electrode. In this work, graphite with 15 wt% silicon monoxide was used as an electrode with trisiloxane-modified binder showing much improved electrochemical performance with better mechanical integrity compared to the benchmark electrode. The cell with modified binder exhibited remarkable cycling stability up to 400 cycles at 0.2 C-rate. A detailed study on the role of the trisiloxane additives on the physicochemical properties of electrode materials has also been elucidated. The prospects of employing these additives for similar high-volume expansion electrodes are also discussed.