An Adhesion-Toughness-Balanced Binder for Stabilizing Silicon-Based Anodes in Pouch Cells

Severe volume expansion of high-capacity silicon-based anodes demands binders with both higher adhesion and superior toughness, which could hardly be achieved by a single polymer. As a prototype, the authors propose a linear-particulate composite network, intelligently designed by highly elastic emulsion particles percolating in a robust 3D framework to construct a binder with adhesion-toughness-balanced properties. In this architecture, the elastic particles can ensure the flexibility of electrodes and act as buffer layers to dissipate the stress generated by volumetric changes of silicon. Meanwhile, the robust framework is responsible for providing strong adhesion through abundant H-bonding interactions and endows the polymer chains with high toughness, which contributes to maintaining the integrity of the electrode. Based on this synergistic model of strong adhesion and optimal toughness, a 2 Ah Si/C (500 mAh g^-1)|NCM90 pouch cell retains high capacity (82.5% of initial capacity) at 1 C after 500 cycles. Remarkably, this binder enables high-capacity Si-based anodes (1800 mAh g^-1) to achieve superior performance with a 73.6% capacity retention over 1800 cycles at 1.5 C in all-solid-state lithium-ion batteries (ASSLIBs), highlighting its wide applicability for next-generation high-performance batteries, including both high-energy Si-based pouch cells and ASSLIBs.