Binder-free 3D flower-like alkali doped- SnS2 electrodes for high-performance supercapacitors

Abstract

Tin disulfide can be a good electrode material in supercapacitors due to the presence of significant interlayer space in crystalline structures and large surface area. However, there are only a few reports of its supercapacitor applications. In this study, we report flower-like pure SnS2 and alkali metals (Li, Na, K and Cs) doped-SnS2 nanostructures synthetized by simple single-step solvothermal method without use of any surfactants. Results show that due to the presence of dopants, with increasing radius of the dopant element, the interlayer distance and dislocation intensity increase. This leads to an increase in the expanded space between interlayer and electro-active sites, and therefore, it is possible to intercalate more ions from the electrolyte. But due to the higher conductivity of Na than the other alkali metals, Na doped-SnS2 shows higher current density at constant voltage and thus better capacitance performance than the others. Na doped-SnS2 exhibits higher supercapacitor performance with a high capacitance of 269 Fg−1 at a current density of 1 Ag−1. The significant electrochemical performance of Na doped-SnS2 can be attributed to its particularly good surface area due to the expansion of interlayer space, increasing of electro-active sites and greater conductivity due to the presence of Na.