A Flexible and Conductive Binder with Strong Adhesion for High Performance Silicon-Based Lithium-Ion Battery Anode

Silicon is considered to be one of the most promising anode materials for lithium-ion batteries due to its high capacity. But the silicon anodes undergo huge volume changes during the charge and discharge process, leading to fast capacity fade of Si anodes. To solve this problem, we design a ternary polymer binder composed of poly (vinyl alcohol), poly(dopamine hydrochloride) and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) for Si anodes. In this polymer composite binder, polydopamine and poly(vinyl alcohol) exhibit strong adhesion with the silicon particles and the copper foils. Additionally, poly (vinyl alcohol) compounded with poly (dopamine hydrochloride) shows high stretchability up to 243.7 %, which benefits for buffering large volume change of Si anodes during cycling. The conducting poly(3,4-ethylenedioxythiophene) : poly (styrene sulfonate) in this binder improves the rate performance. Using this multi-functional binder, the Si anodes show excellent cycling stability even under high Si mass loading.