Stable Zn anodes enabled by high-modulus agarose gel electrolyte with confined water molecule mobility

In aqueous electrolyte, the hydration of solvated zinc ions and the unstable deposition interface exacerbate the accumulation of Zn dendrites and the generation of by-products, making it difficult to achieve highly reversible and long-life Zn-ion batteries (ZIBs). Herein, a high-modulus agarose gel electrolyte (AGE) with greatly suppressed H2O molecule mobility, is designed to overcome the above challenges. The ample hydroxyl (-OH) functional groups on the double helix chain of the AGE can capture and anchor H2O molecules via hydrogen bonding, thus fundamentally regulating the coordination environment of Zn2+ and enhancing the stability of deposition interface. Moreover, the -OH functional groups can also effectively immobilize sulfate ions and largely confine their free diffusion, thereby greatly inhibiting the formation of zinc hydroxysulfate by-product. As such, the dendrite issue and side reactions can be significantly mitigated using our designed AGEs, holding great promise for ZIBs with extended cycling durability and high safety.