Achieving a dendrite-free Zn anode at high current densities via in situ polymeric interface design

Abstract

The lack of Zn anode protection is one of the hindrances to the further development of aqueous Zn ion batteries. The uneven plating morphology of Zn will lead to the formation of dendrites, largely impeding practical applications of the battery due to internal short circuits. Herein, adding acrylamide (AM) monomers establishes an in situ protective layer that effectively yields smooth plating interfaces, thus mitigating the side-reactions of corrosion and passivation. Polyacrylamide (PAM) was successfully synthesized on Zn foils, and the Zn₅(OH)₈Cl₂·H₂O-doped macromolecular skeleton subsequently provided a site for Zn²⁺ plating. Simulation and experimental results demonstrated that the skeleton gradually induces Zn deposition along the (002) plane, thus achieving a dendrite-less interface. Consequently, the symmetrical cell allows for significantly prolonged cycling for about 1400 h under a current density and area specific capacity of 10 mA cm⁻² and 5 mA h cm⁻², although remarkable stability is maintained under more severe conditions (40 mA cm⁻², 40 mA h cm⁻²). Practical feasibilities based on introducing the AM additive are proved in Zn//NH₄V₄O₁₀ full cells. This work highlights the applicability of in situ polymerization of a SEI film to realize interfacial stability by introducing an additive strategy for high-performance aqueous Zn ion batteries.