Practical guidelines for reliable electrochemical testing of cathodes in aqueous zinc-ion batteries: The case study of amorphous and crystalline α-MnO2

Abstract

The rechargeable aqueous zinc-ion battery (AZIB) provides several advantages, including affordability, safety, and environmental friendliness. The development of effective cathode materials is crucial for the practical applications of AZIBs. Despite significant efforts to explore various cathode materials, the optimal conditions for reliable electrochemical measurement have not been fully established. Therefore, this study aims to investigate the effects of separators and binders on the electrochemical properties of amorphous and crystalline α-MnO2 cathodes for AZIBs. The scratched polypropylene separator prevents reactions between the α-MnO2 cathode and glass fiber separator during electrochemical measurements. The hydrophilic binder enhances charge-discharge capacity, while the hydrophobic binder demonstrates superior long-term cycling performance for the α-MnO2 cathode. The microstructural homogeneity of pristine α-MnO2 powder is crucial for maintaining stability and reducing electrochemical resistances after extended electrochemical measurements. Our findings establish the role of the separator and binder in rechargeable aqueous batteries and provide practical guidelines for reliable electrochemical measurement of cathodes, resulting in significant improvements in battery performance.