Zinc saponite protection layer with fast zinc-ion transfer kinetics to enable highly reversible Zn anode

The performance of zinc anode in aqueous zinc metal batteries is severely challenged by dendritic growth and side reactions. Here, a zinc saponite (NLZS) protective layer strategy with "cation-regulation" is explored to realize dendrite-free zinc metal anode. The abundant negative charge channels confer unique cation selectivity to the NLZS protective layer, homogenizing the interfacial electric field while regulating zinc-ion flux, ensuring uniform zinc deposition and inhibiting interfacial side reactions. Consequently, the functional NLZS protective layer enables the zinc anode to deliver an average coulombic efficiency of more than 99.5 % at 5 mA cm−2 and a cycle life of more than 1600 h at 0.5 mA cm−2. Furthermore, both MnO2-based full batteries and zinc-ion capacitors exhibit outstanding rate performance and cycling stability. This work not only provides a simple and cost-effective protection strategy for the zinc anode but also holds promise for practical applications.