Nature-inspired design of NiS/carbon microspheres for high-performance hybrid supercapacitors

Yeast, as a natural rich-nitrogen biotemplate, holds great potential for designing of carbon microspheres (CMS) towards electrochemical devices. We rationally design and synthesize novel NiS/CMS binary hybrid microspheres by using biological yeast as carbon parental template. It is found that the introduction of bio-charcoal and the good NiS/CMS interface effect are the crucial factors for the application of electrochemical capacitors. These NiS/CMS binary hybrid microspheres show high specific capacitance of 1594 F g(-1) at 1 A g(-1), and the hybrid supercapacitor (HSC) display great energy density, power density, and improved cycling stability. Density functional theory (DFT) calculations indicate that NiS/CMS composite enhances the Ni d-orbital electronic states around the Fermi level, and meanwhile the unique electronic arrangement of d-orbital promotes synergistically the overall composite redox reaction. The concept of hybrid construction of electrode can serve as a hopeful option for developing high energy density supercapacitors.