Electrochemical Performance of Quasi-Solid-State Rechargeable Zinc Batteries Using Alginate Hydrogel Electrolyte Membranes

抄録

Rechargeable zinc batteries (RZBs) have received much attention due to high theoretical specific capacity and high hydrogen overpotential of zinc, low cost, and safety. However, the electrolyte leakage, dendritic zinc deposition, some side reactions, and zinc hydroxide sulfate (ZHS) byproduct formation on the zinc negative electrode cause the deterioration of RZBs. Hydrogel electrolytes retaining large quantities of electrolytes can suppress leakage and regulate the transport of zinc ions via a three-dimensional host polymer network, overcoming these drawbacks. In this study, flexible alginate hydrogel electrolyte membranes (AHEMs) were successfully prepared by combining the formation of hydrogel membranes using 1,3-propanediol as a plasticizer with subsequent immersion in a Zn²⁺-containing aqueous solution. The AHEM exhibited ionic conductivity comparable to that of corresponding Zn²⁺-containing solution. Zinc deposition proceeded uniformly in AHEM, and the formation of ZHS was effectively suppressed. The symmetric Zn/AHEM/Zn cell showed a stable voltage profile without short-circuits for more than 2000 h in a charge-discharge test at 4 mA cm⁻² for 30 min. The pouch-type quasi-solid-state Zn/AHEM/MnO₂ cell maintained approximately 70 % of its maximum discharge capacity even after 300 cycles in the charge-discharge cycle test at a 3 C-rate (= 924 mA g⁻¹).