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

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.