Effects of transition-metal ions on the morphology and electrochemical properties of δ-MnO 2 for supercapacitors

摘要: δ-MnO2 materials doped with transition-metal cations (Zn, Co, and Ag) were successfully synthesized using a hydrothermal technique. The structures morphologies of the obtained oxides analyzed X-ray diffraction, scanning electron microscopy Brunauer-Emmett-Teller measurements. Additionally, electrochemical properties evaluated through cyclic voltammetry, impedance spectroscopy galvanostatic cycling results indicate that pure samples crystallize in δ form layered structure Mn/Zn, Mn/Co Mn/Ag molar ratios are all approximately 1:0.09. Both Zn-doped MnO2 exhibit petal-like morphology; however, former has higher specific surface area up to 98.97m2 g−1. Furthermore, exhibits near-rectangular voltammetry (CV) curve broad quasi-reversible redox peaks capacitance 182.9 F g−1 at CV scan rate 2 mV s−1. Co-doped material distinct spiny-fiber morphology, performance this is significantly worse than MnO2. average attenuation Ag-doped only 0.028% after 1000 cycles, which lower