An anode-free sodium dual-ion battery

Batteries with both high energy and power densities are desired for practical applications. Constructing anode-free 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/striping 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.