Stable cycling of a Prussian blue-based Na/Zn hybrid battery in aqueous electrolyte with a wide electrochemical window†
Abstract
Rechargeable aqueous batteries have received widespread interest for large-scale energy storage because of their intrinsic advantages of safety, low cost and environmental friendliness. However, great challenges still remain for developing long-life batteries with aqueous electrolytes. In this work, an aqueous hybrid battery composed of a sodium iron hexacyanoferrate (FeHCF) cathode and a zinc anode has been proposed. The coating of polyamide on Zn is effective in regulating uniform Zn plating/stripping and suppressing Zn corrosion in the aqueous electrolyte. The electrochemical window of the electrolyte was extended to 3.3 V and the dissolution of the FeHCF cathode was obviously suppressed by adding 2 vol% vinylene carbonate to the 7 M NaCF3SO3/0.1 M Zn(CF3SO3)2 solution. As a result, the aqueous electrolyte delivers a relatively high specific capacity of 75 mA h g−1 at 1C (100 mA g−1) and exhibits a good cycling stability (60% capacity retention after 4000 cycles at 10C), showing promising applications in energy storage.