Sustainable biopolymeric hydrogel interphase for dendrite-free aqueous zinc-ion batteries

Naturally derived hydrogels have emerged as advanced manufacturing materials due to their biosafety, biocompatibility, and eco-friendly property while retaining large amounts of water. Here, we demonstrate that biopolymeric hydrogel interphase derived from abundant natural polysaccharide exhibits successful stabilization of 3D structured Zn anodes for dendrite-free aqueous zinc-ion batteries (ZIBs). The cross-linked natural hydrogel interphase on Zn anodes guides the uniform stripping/plating of Zn2+ for dendrite-free homogeneous Zn deposition and effectively avoids direct contact between reactive aqueous electrolytes and Zn anodes, inhibiting the parasitic side such as the hydrogen evolution reaction. Furthermore, the thin hydrogel interphase enables employing liquid electrolytes without lowering volumetric energy density. Such characteristic allows high ionic conductivity and, more importantly, significantly reduces cell resistance compared to previous ZIBs with only hydrogel electrolytes. These features afford highly stable zinc plating/stripping behaviors at high areal current density (10 mA cm−2) and capacity (2 mAh cm−2) for 1500 h, enabling durable cycle stability of full cells paring with MnO2 cathodes during 3000 cycles at 2 Ag−1 without capacity fading. Our strategy not only suggests a "green" method for developing dendrite-free aqueous ZIBs but also provides natural polymers with expansion into future aqueous energy storage fields.