Electrolyte additives inhibit the surface reaction of aqueous sodium/zinc battery

Abstract

In aqueous zinc-based batteries, the reaction by-product Zn4SO4(OH)6·xH2O is commonly observed when cycling vanadium-based and manganese-based cathodes. This by-product obstructs ion transport paths, resulting in enhanced electrochemical impedance. In this work, we report a hybrid aqueous battery based on a Na0.44MnO2 cathode and a metallic zinc foil anode. The surfactant sodium lauryl sulfate is added to the electrolyte as a modifier, and the performance before and after modification is compared. The results show that sodium lauryl sulfate can generate an artificial passivation film on the electrode surface. This passivation film reduces the generation of Zn4SO4(OH)6·xH2O and inhibits the dissolution of Na0.44MnO2 in the electrolyte. Therefore, the reaction kinetics and cycle stability of the battery are significantly enhanced. A battery with this electrolyte additive delivers an initial discharge capacity of 235 mA h g−1 at a current density of 0.1 A g -1. At the same time, the battery has excellent rate performance. Under the high-rate condition of 1 A g−1, the battery still maintains a capacity retention rate of 93% after 1500 cycles. Finally, the functional mechanism of by-product inhibition by the electrolyte additive is discussed.