An anode-free sodium dual-ion battery

Batteries with both high energy and power densities are desired for practical applications. Constructing anodefree batteries is effective to achieve high energy density, yet remains highly challenging to obtain high power density simultaneously. To overcome this dilemma, dual-ion storage strategy is introduced to anode-free battery. As a proof of concept, an anode-free sodium dual-ion battery (AFSDIB) with combined high energy and power densities is successfully fabricated. Plasma-treated current collector (Al/N-C) exhibits a sodiophilic N -doped carbon surface, enabling highly reversible Na plating/stripping at high current densities. Meanwhile, the sluggish desolvation process is intrinsically eliminated at the polytriphenylamine (PTPAn) cathodic side owing to the solvation-free anion storage chemistry. Consequently, the assembled Al/N-C||PTPAn AFSDIB exhibits a remarkable energy density over 380 Wh kg -1 (at 375 W kg -1 ) and power density above 1800 W kg -1 (at 302 Wh kg - 1 ) based on active materials and consumed electrolyte, which is superior to the reported state -of -the -art anode-free and dual-ion sodium batteries. This work paves a new pathway for developing batteries with both high energy and power densities.