Microstructure and Electrochemical Properties of ZnMn2O4 Nanopowder Synthesized Using Different Surfactants

ZnMn₂O₄ (ZMO) nanopowders have been synthesized by a hydrothermal method using different surfactants [cetyltrimethylammonium bromide (CTAB), polyethylene glycol (PEG)-400, and Polysorbate-80]. The as-prepared ZnMn₂O₄ samples exhibited single phase with tetragonal structure, showing honeycomb, spinel microsphere, and flower-cluster morphology, respectively. Cyclic voltammetry curves for all samples presented rectangular shape with symmetric nature and good cycling properties, with no obvious redox peak. Galvanostatic charge–discharge curves were triangular and symmetric. The specific capacitance of the ZnMn₂O₄ nanopowders gradually decreased with increase of the scanning rate. ZMO-PEG exhibited higher specific capacitance of 191 F g^?1 at scan rate of 5 mV s^?1 and retained superior large-current cycling stability of 98.4% after 1000 cycles compared with ZMO-CTAB (93.8%) or ZMO-Polysorbate-80 (97.7%). Electrochemical impedance spectroscopy revealed that the ZnMn₂O₄ nanopowders had low resistance. These results suggest that ZnMn₂O₄ nanopowders have good capacitance characteristics.