Preparation of zinc-doped bagasse-based activated carbon multilayer composite and its electrochemical performance as a supercapacitor

The improvement of pseudo-capacitance is the most important factor affecting performance of supercapacitor. MnO2 is an ideal material for the development of pseudo-capacitance, but its increased load amount while reducing its load thickness still is puzzled. In this study, a two-step method of loading MnO2 on the surface of activated carbon (ZAC) prepared by ZnCl2 activation bagasse was conducted to devote problem. A series of AMCM-X composites (ZAC@alpha-MnO2/CNTs/8-MnO2) with layered structures were obtained by sequentially loading linear nano-alpha-MnO2, CNTs, and sheet nano-8-MnO2 on ZAC using hydrothermal, freeze-drying, and electrochemical deposition methods, respectively. The loading of CNTs extended external space of substrate and facilitated further loading of 8-MnO2. Further, the AMCM-4 material had a mass specific capacitance of 450 F/g at 1 A/g and the asymmetric supercapacitor of AMCM-4//ZAC still had 92.3% capacitance retention rate after 5000 cycles. Moreover, XPS results showed the thickness of 8-MnO2 (0.35 wt%) was relatively thinner than alpha-MnO2 (1.93 wt%). The mechanism by which composites improved the electrochemical performance of the supercapacitor was attributed to the ability of building and covering pores of CNTs on substrate. These results will increase the re-negotiation of bagasse and improve the pseudo-capacitance of MnO2 in supercapacitors.

Automated summary

The improvement of pseudo-capacitance is crucial for the performance of supercapacitors, with MnO2 being an ideal material for this purpose. A two-step method was used to load MnO2 onto ZAC, resulting in enhanced electrochemical performance. By sequentially loading alpha-MnO2, CNTs, and 8-MnO2 on ZAC, the composite material showed promising results in terms of capacitance retention and efficiency after 5000 cycles.