Nature Plant Polyphenol Coating Silicon Submicroparticle Conjugated with Polyacrylic Acid for Achieving a High-Performance Anode of Lithium-Ion Battery

Silicon as an anode material of a Li-ion battery has attracted many researchers widespread attention for proper lithium intercalation potential and superhigh theoretical capacity. However, a Si-based anode possesses so poor a cycle life that it cannot be commercialized on account of the drastic volume expansion of silicon particles in the process of charge/discharge. Herein, we present a simple, green, and inexpensive way to improve cycle life of silicon-based electrodes by modifying active materials (more cheap and fragile Si submicroparticles (SiSMPs) than silicon nanoparticles) using tannic acid (TA) (a biocompatible nature plant polyphenol) and then interacting it with poly(acrylic acid) (PAA) binder. The tannic acid conformal coating can protect SiSMPs from side reactions with the electrolyte and can conjugate with the PAA binder and conductive materials, which keeps the electrode structure integrity during cycling. Furthermore, the TA coating makes the PAA binder form a 3D cross-linked network, which can enhance the binding strength compared with linear PAA chains, and the wet adhesion of the TA mussel-inspired coating can ensure good adhesion between SiSMPs and other components in electrolytes. Therefore, the combination between moderate amounts of TA coating and PAA can improve cycle performance and rate performance of low-cost submicrosized Si particle-based Li-ion battery anodes.