CTAB controlled electrochemical deposition of manganese dioxide with enhanced performance in aqueous Zn-ion battery

The collapse and dissolution of the structure of the MnO2 positive electrode in the cycle process is mainly caused by the volume expansion during the phase transition process, which leads to the extrusion of the adjacent parts of the electrode and poor cycle performance. To overcome this issue, morphology of MnO2 films were controlled by adding various concentrations of surfactant Hexadecyl trimethyl ammonium Bromide (CTAB) in the electrolytic cell through changing the current distribution characteristics between substrate and solution. The obtained MnO2 nanofilm materials prepared with different concentrations of surfactant were compared from the aspects of surface morphology, specific capacity and cyclic stability. The morphology and structure of the prepared MnO2 were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer Emmett and Teller (BET). As expected, MnO2 with its unique crystal structure exhibited excellent cycling and superior performance (311.2 mAh g−1 at 0.1 A g−1, 177.6 mAh g−1 at 5 A g−1, 125% capacity retention after 4000 cycles at 5 A g−1). This capacity retention was among the highest reported so far for MnO2-based cathode materials for Zn-ion batteries. The excellent electrochemical performance may be due to its unique nanostructure, which provides enough space for the volume expansion and proper structure for the re-deposition of MnO2. This work provides an new sight to develop long-circulation MnO2 electrodes for aqueous Zn ion batteries by designing an advantageous master structure dynamics.