Understanding the Role of a Water-Soluble Catechol-Functionalized Binder for Silicon Anodes by Diverse In Situ Analyses

Traditional binders generally interact with silicon particles via weak van der Waals forces and consequently lack interactions between active materials after volume expansion. Water-soluble binders have recently garnered lots of attention as low-cost and environmentally benign aqueous media to overcome the main challenges with practical processing considerations. Herein, we report the development of a multifunctional polymeric binder having a three-dimensional network structure for silicon-based anodes, providing three advantages over traditional binders: greater structural integrity against expansion, stronger adhesion to anode components, and higher ionic conductivity. Diverse operando observations clearly show that the novel multifunctional binder mitigates the microstructural changes of silicon at nanoscale and microscale levels compared to conventional linear binders, resulting in a high electrochemical performance of approximately 1100 mAh g–1 even after 1000 cycles. Our systematic study on the effects of this multifunctional binder will be of great help in the rational design of polymer binders for advanced batteries.