Bonding layer reinforcing the interface of binder-free Sb-based electrode for improved cycling stability of sodium ion batteries.

Abstract

Compared to traditional electrodes, binder-free electrodes have attracted extensive attention due to their high energy density. However, the absence of binders results in weak connection between the active material and the current collector, which can cause active materials to detach from the collector, especially in alloy-type electrode such as Sb with severe volume change. Herein, we report an electrochemically inactive Ag₃Ga film as a bonding layer between Sb film and stainless steel mesh (ssm). The bonding strength is further enhanced by annealing at 400 °C, during which Sb film alloyed with Ag₃Ga to form GaSb film (GaSb@Ag₃Ga-400). As for anode of sodium ion batteries (SIBs), the GaSb@Ag₃Ga-400 electrode operated in 0.01-0.75 V (vs. Na⁺/Na) exhibits excellent cycling stability (245.9 mAh g^-1 after 400 cycles at 1 A g^-1) and satisfactory rate capability (205.3 mAh g^-1 at 3 A g^-1). The sodium storage kinetics of GaSb@Ag₃Ga-400 electrode was further characterized by cyclic voltammetry at different scan rates and galvanostatic intermittent titration technique. More importantly, the alloying/dealloying storage mechanism of GaSb@Ag₃Ga-400 electrode was revealed by in situ X-ray diffraction analysis. The present work presents the significant potential of Ag₃Ga film as a robust bonding layer for binder-free electrode with long-term cycling stability and offers available insights for the development of other binder-free electrodes.