Robust 3D Network binder for Stable and High‐Performance Si‐Based Lithium‐Ion Battery Anodes

Abstract Silicon (Si) is becoming one of the most promising candidates for lithium‐ion batteries (LIBs) owing to its high theoretical capacity, ultralow lithiation/delithiation voltage, non‐flammability, abundant natural reserves, etc. However, Si particles undergo violent volume expansion/contraction during the charge/discharge cycles, resulting in a series of serious problems such as Si particle pulverization, solid electrolyte interphase film overgrowth, and electrode structure collapse, which severely hinders the application of silicon‐based LIBs. Herein, a composite binder crosslinked by polyacrylic acid and p‐toluene sulfonic acid protonated polyaniline is proposed to improve the electrochemical performance of Si‐based anodes. The cross‐linked composite binder processes 3D networks, fast self‐healing features, and excellent mechanical strength, which can alleviate the damage caused by the expansion of Si particles to the electrodes and protect the structural integrity of the Si‐based electrodes. As a result, the Si‐based anodes with the composite binder present excellent cycle stability (2092.9 mAh g−1 after 300 cycles at 400 mA g−1). In addition, the novel binder reveals well compatibility with commercial Si microparticles. More importantly, the self‐healing Si anode is firstly equipped in an all‐solid‐LIB with solvate ionic liquid‐based quasi‐solid electrolyte and shows excellent cycling stability as well as rate capability.