In situ interlocked gradient adaptive network binder with robust adhesion and cycle performance for silicon anodes

The potential for silicon anodes as an alternative to graphite anodes for lithium-ion batteries (LIBs) has been extensively studied. Unfortunately, structural and interfacial instability limits their commercial application. Polymer binder design preserves the electrode's structure against large Si volume changes in LIBs, thereby improving battery cycle life. Developing robust conductive binder networks is essential for optimizing anode capacity potential. Herein, a biopolymer composite binder (IFH) composed of flexible hyaluronic acid and fluorinated copolymer inspired by constructional engineering is constructed. In situ interlocked is achieved by establishing multi-hydrogen bonding networks and chemical bonding between polar groups in the copolymer chain. IFH exhibits excellent mechanical characteristics as well as flexibility and elasticity. In addition, the covalent bonds between ester and amide bonds effectively enhance the mechanical properties of the electrode, inhibit the sliding of silicon particles, maintain the integrity of LIBs, and improve the conductivity of lithium-ion. Specifically, excellent electrochemical performance (1049 mAh g−1 at 1 A g−1 after 500 cycles) of silicon/carbon anodes fabricated with gradient adaptive network IFH binder was achieved. Moreover, SiO–C composite electrodes as well as Si–C electrodes show excellent electrochemical performances. This work provides new insights into the design of multifunctional polymer binders for next generation LIBs.