Natural Gluten Binder Enabling High‐Performance Hard Carbon Anode in Sodium‐Ion Batteries

Abstract Hard carbon (HC) is gaining recognition as a prospective anode material for sodium‐ion batteries (SIBs), showing considerable promise in energy storage applications. The binder is a key determinant of the microenvironment of electrodes, which controls the charge transport and mechanical properties. Herein, the study investigates the application of Gluten (GT), a natural mesh binder, for enhancing overall properties of the HC anode. It is found that the numerous functional groups in GT quickly form hydrogen bonds with HC particles after a slight hydration, effectively improving mechanical interlocking and significantly reducing mechanical degradation during cycles. Advanced characterization in combination with theoretical simulations shows that GT reduces the dissociation energy of PF ₆ ⁻ , which promotes the formation of a thin, uniform NaF‐rich solid‐electrolyte interface (SEI) on the HC anode surface. Consequently, HC‐GT demonstrates outstanding electrochemical performance, retaining 83% of its capacity after 1000 cycles at 0.5 A g ⁻¹ and achieving an initial coulombic efficiency of ≈88%. Moreover, the full cell demonstrates excellent cycling stability, with a capacity of 75.8 mA h g ⁻¹ after 800 cycles at 1 C. This work underscores the significance of selecting appropriate binders to achieve high‐performance anodes, offering a new perspective for optimizing the electrochemical performance of SIBs.