Gel electrolyte interdigitation enables stable high areal capacity cycling of the 3D Zn electrode†

Inferior rechargeability of the metallic zinc anode, especially under high areal capacities and moderate to high current densities, remains a significant bottleneck for developing scalable aqueous zinc-ion batteries. While three-dimensional (3D) porous zinc anodes can mitigate high local current density and enhance deposition kinetics, limited electrolyte percolation within the 3D framework with conventional liquid electrolyte-soaked separator leads to surface-concentrated ion flux, which confines zinc nucleation and growth to the uppermost surface. This results in early short-circuit events mediated by dendrites. Here, electrolyte-interdigitation with a biopolymer hydrogel electrolyte is presented as a facile strategy, which by design enables complete electrolyte percolation within the porous and tortuous structure of the 3D zinc and uniform mass transport across the whole electrode structure. The increased accessible surface area and interconnected transport pathways effectively regulate zinc plating/stripping, thus maintaining the structural integrity upon cycling. As a result, the integrated design enables extended zinc rechargeability and a cumulative cycling capacity of 1680 mA h cm⁻² under demanding 5 mA cm⁻²–5 mA h cm⁻² conditions. Suppressed corrosion and dendrite inhibition for the interdigitated anode also leads to excellent rate capability and stability of the full-cell, highlighting a significant advance in the field of 3D zinc anode design.