The effects of cross-linking cations on the electrochemical behavior of silicon anodes with alginate binder

Abstract

Silicon is one of the most promising anode candidates for the next generation Li-ion batteries. Polymer binders play a crucial role as they are very essential to keep mechanical integrity of the electrodes and affect the solid electrolyte interphase (SEI) properties. Alginate appears to be the best binder system for Si electrode and it is able to form three-dimensional (3D) conductive polymeric network through in-situ inter-chain cross-linking by divalent cations. Herein, the effects of different cross-linking cations (Cu2+, Ca2+, Fe2+ and Ni2+) on the electrochemical behavior of silicon nano-sized particle anodes with alginate binder are investigated. It is found that all the alginate networks bridged by the transition metal cations are able to tolerate the volume change of silicon and effectively restrict the volume expansion of the Si particles. The overall electrochemical properties of the Si anode with Ni cations cross-linked alginate exhibit the highest reversible capacity, extraordinary cycleability and superior rate capability. The main reason for the electrochemical enhancement is explained by the improved stability of SEI film on the Si surface.