Rapid Synthesis of Hierarchical Tin Disulfide (SnS2) Nanostructures by a Microwave-Assisted Hydrothermal Method for High-Performance Supercapatteries

Supercapatteries bridge the gap between supercapacitors and rechargeable batteries. These electrochemical energy storage devices possess a higher energy density than supercapacitors and higher-power density than batteries. The charge storage mechanism in a supercapattery is similar to that of batteries, i.e., mainly by means of diffusion-controlled mechanisms. The positrode and negatrode of a supercapattery should be designed in such a way to achieve maximum electrochemical performance. Transition metal sulfides are potential candidates as positrode materials for supercapatteries. Herein, we report the rapid synthesis of flower-like tin disulfide (SnS2) nanostructures by a microwave-assisted hydrothermal method and its application as a positrode material in supercapatteries. By varying the transition metal to sulfur ratio, the SnS2 nanostructure is optimized to achieve a large surface area and porous architecture to achieve a maximum electrochemical performance when used as an electrode-active material for supercapatteries. The flower-like layered SnS2 delivered a maximum specific capacity of 165.6 C/g at scan rates of 3 mV/s in 2 M KOH (aqueous) electrolyte. The SnS2 electrode exhibits an excellent electrochemical cyclic stability of more than 5000 cycles. Further, with an asymmetric supercapattery fabricated with SnS2 as a positrode and activated carbon as a negatrode, the device delivers a maximum specific capacity of 114.8 C/g with a corresponding energy density of 23.9 Wh/kg when tested in a two-electrode cell compartment using a 2 M KOH (aqueous) electrolyte.