Achieving ultrahigh initial Coulombic efficiency in SnBi/C anode for sodium-ion batteries via interfacial engineering and binder optimization

The designed deep-eutectic Sn-Bi bimetallic carbon composite microspheres (SnBi/C) with abundant phase boundaries, effectively alleviate volume deformation during sodium (de)intercalation. Accordingly, the anode fabricated with poly(ethylene oxide) binder delivers an ultrahigh initial Coulombic efficiency of 95.4%, along with high reversible capacity and excellent cycling stability.