Amorphous manganese silicate anchored on multiwalled carbon nanotubes with enhanced electrochemical properties for high performance supercapacitors

Amorphous manganese silicate/multi-walled carbon nanotubes (AMSi/MWCNTs) composites were successfully synthesized using MWCNTs, manganese dichloride and sodium silicate as the starting materials by a facile precipitation method. The composition and morphology were characterized by X-ray powder diffraction, energy-dispersive X-ray spectrometer, elemental mapping, Raman, Fourier transform infrared spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. Electrochemical properties of AMSi/MWCNTs as supercapacitor electrode were studied. It was found that the electrochemical performance of AMSi could be adjusted by the amount of MWCNTs. Specific capacitance of AMSi/MWCNTs reached the highest value (236 F g(-1) at 0.5 A g(-1)) in the presence of 40 wt.% of MWCNTs. Asymmetric supercapacitor device assembled from AMSi/MWCNTs and activated carbon (AMSi/MWCNTs//AC) showed its specific capacitances reached 146, 139, 119, 108 and 99 F g(-1) at current densities of 0.5, 1, 2, 5 and 10 A g(-1), respectively. A capacitance retention of 81% for AMSi/MWCNTs//AC device after 1000 cycles indicated that AMSi/MWCNTs had good cycling performance applied to SC device. Present findings demonstrated that MWCNTs could improve the electrochemical properties of AMSi and suggested that AMSi/MWCNTs composites could be considered as potential materials for high-performance energy storage device.