Morphological structure is of great significance for supercapacitors. Designing materials with diverse morphologies has attracted considerable attention, as it can achieve impressive electrochemical performance in energy storage technologies. Therefore, in present investigation, two differentiated hydrothermal synthesis methods were employed to successfully prepare nanoflowers and nanosphere MnO 2 . Characterization results revealed that both MnO 2 samples with distinct morphologies possessed the same crystal structure. However, the nanosphere MnO 2 exhibited a higher specific surface area and a wider pore size distribution, thereby demonstrating more excellent electrochemical performance. Specifically, in 1 M Na 2 SO 4 electrolyte, the specific capacitance of nanosphere MnO 2 reached 162 F g -1 , while that of nanoflowers MnO 2 was only 113 F g -1 . An asymmetric supercapacitor was assembled using the nanosphere MnO 2 as the positive electrode and activated carbon as the negative electrode in 3 M KOH electrolyte. After 5000 charge-discharge cycles at a current density of 5 A g -1 , the device still maintained a high capacity retention rate of 95 %, exhibiting outstanding cycling stability.
Wang et al. (Tue,) studied this question.