Ozone-treated acetylene black as conductive agents for cathodes in aqueous zinc-ion batteries

Manganese dioxide cathodes offer high operating voltages and energy densities, showing great potential for use in aqueous zinc-ion batteries. However, their practical use has been limited by poor cycling stability caused by Mn2+ dissolution and structural degradation in the cathodes. In this work, oxygen-deficient γ-MnO2 (γ-MnO2-x) was prepared and ozone-oxidized Acetylene Black was employed as a conductive agent to enhance the cycling stability of the cathode. After ozone treatment, the Acetylene Black shows reduced particle size and increased specific surface area, which is conducive to the formation of a uniform conductive network, thus facilitating electron and ion transport. Moreover, oxygen-containing functional groups on the modified Acetylene Black surface can help maintain the original Mn valence state of γ-MnO2-x and suppress cathode degradation during long-term cycling. Consequently, the cathode with oxidized Acetylene Black achieved a high capacity retention of 81.8% after 2000 cycles at 1.5 A g−1, markedly higher than the 49.5% retained by the cathode employing pristine Acetylene Black. This study presents an effective strategy for modifying conductive agents and provides new insights toward achieving stable cycling performance of MnO2 cathodes in aqueous zinc-ion batteries.