Carboxymethyl Cellulose Gel Electrolyte Based on Hydrolyzed Keratin Modified for Dendrite-Free Zinc-Ion Batteries

In order to alleviate the dendrite problem of zinc-ion batteries, a gel electrolyte is prepared by Maillard reactions occurring between hydrolyzed wool keratin and carboxymethyl cellulose under heating conditions. The prepared gel electrolyte with the addition of hydrolyzed wool keratin possesses good mechanical properties, and its maximum breaking strength, Young's modulus, and elastic modulus are 58.7, 10.77 MPa, and 157.73 MJ m², respectively, which are far superior to those of the pure carboxymethyl cellulose gel electrolyte. Because hydrolyzed wool keratin includes amino acids and polypeptides, the ionic conductivity of the prepared gel electrolyte is improved. More importantly, amino and carboxyl groups introduced by hydrolyzed wool keratin contribute to uniform deposition of zinc ions and ease dendrite growth. The assembled symmetric battery was stable for 600 h at a current density of 0.5 mA cm^-2 with a capacity of 0.5 mAh cm^-2. Combined with a NH₄V₄O₁₀ cathode, a full battery provides a cycling stability of over 2000 h with a Coulomb efficiency of 98.02%.