Plant-based hydrogel tames zinc dendrites, pushes aqueous batteries past 1 000 stable cycles

Aqueous zinc-ion batteries promise safe, low-cost energy storage, but metallic zinc grows needle-like dendrites that short-circuit cells within a few hundred cycles. Now, a purely plant-derived hydrogel appears to solve the problem without resorting to toxic additives or expensive ceramics.
The team dissolved microcrystalline cellulose in an alkali/urea ice bath, then stitched the polymer together with borax to form the primary network. Into this scaffold they embedded TEMPO-oxidised cellulose nanofibres—ribbon-like strands 3 nm thick and hundreds of nanometres long that carry dense carboxyl groups. The nanofibres act as both mechanical rebar and ionic expressways: molecular-dynamics simulations show Zn2+ diffusion along the composite climbs to 4.59 × 10-4 m2 s-1, almost double that of plain cellulose.
Mechanical tests reveal the optimised film—only 1 mm thick—hits 0.57 MPa tensile strength after soaking in 2 M ZnSO4, four times tougher than the cellulose-only control yet still 62 % transparent. Symmetric Zn//Zn cells cycled at 0.5 mA cm-2 survive 1 100 h without sudden voltage drop, while commercial glass-fibre separators fail after 120 h. Even at 10 mA cm-2 the hydrogel endures 650 h, and a 45 °C oven test shows four-fold longer life than the liquid benchmark.
When paired with a NaCl-pre-treated V2O5 cathode, full cells deliver 237 mAh g-1 at 0.2 A g-1 and keep 79.9 % of their capacity after 1 000 cycles at 1 A g-1; liquid electrolytes fade to 69.4 %. Post-mortem AFM images show the protected zinc surface stays smooth (Ra ≈ 52 nm) whereas the liquid counterpart grows rough dendritic nodules (Ra ≈ 108 nm).
Crucially, the material is designed for real-world manufacturing. All ingredients—cellulose powder, bamboo pulp, borax and ZnSO4—are commodity chemicals, and the gel can be cast on rolls like papermaking. Costings show 1 cm2 of the bio-gel costs only 8 % of a commercial glass-fibre separator, while cellulase digestion disposes of it within four hours, offering an end-of-life route conventional membranes lack.
Flexible pouch cells built with the electrolyte continue to power a timer while bent to 90° under a 2 kg weight, hinting at wearables or e-textile uses. The authors say the same cross-linking chemistry should work with sodium or aluminium salts, potentially widening the sustainability dividend to other post-lithium chemistries.
With funding agencies in China backing scale-up trials, the cellulose hydrogel looks set to leave the lab and enter pilot coating lines—turning abundant plant waste into the quiet guardian of next-generation safe batteries.
 

See the article:

DOI

https://doi.org/10.1016/j.jobab.2026.100232

Original Source URL

https://www.sciencedirect.com/science/article/pii/S2369969826000046

Journal

Journal of Bioresources and Bioproducts