Unlocking the potential of highly stable pseudocapacitive performance in asymmetric SnS/Graphite||AC hybrid supercapacitors via hydrothermal method

Abstract

Tin-based chalcogenides are promising materials for energy storage but are hindered by intrinsic low conductivity and structural instability. Here, we report a high-performance tin sulfide/graphite (SnS/G) composite that addresses these challenges by strategically incorporating graphite into the SnS matrix. Graphite enhances electrical conductivity, alters the interlayer spacings and provides a stress-buffering network, significantly improving the composite's electrochemical stability. The SnS/G composite, fabricated via a cost-effective hydrothermal method, exhibits a micro-rod morphology with high surface area and excellent ionic transport properties. Electrochemical characterisation of the SnS/G electrode in half-cell configuration reveals a remarkable specific capacitance of 411.6 F/g at 1 A/g and exceptional cycling stability, retaining 96 % of its initial capacitance after 1200 cycles. When assembled into an asymmetric supercapacitor (ASC) with activated carbon (AC) (SnS/G||AC (1.0 V)), the device achieves a specific capacitance of 187 F/g. Along with an energy density of 26.03 Wh/kg, a power density of 5000 W/kg and outstanding long-term stability with 86 % retention after 25,000 cycles for the full cell is achieved. For SnS/G 10 %|| AC (1.5 V) device delivers an energy density of 39.50 Wh/kg and a power density of 7500 W/kg, with 92 % retention after 6000 cycles. These findings underscore the promise of SnS/G composites as scalable, low-cost, high-performance electrodes for next-generation energy storage systems.