Improved performance in asymmetric supercapacitors using SnO₂-MoS₂ composite microspheres

This paper reported the facile synthesis of SnO2, MoS2, and SnO2-MoS2 composite material via sol-gel method with ex-situ hydrothermal method and utilized for supercapacitor applications. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis confirmed the structural and morphological features. At the same time, the electrochemical performance was analyzed by CV, CD, and well-known impedance analysis via a Nyquist plot in three-electrode assembly in KOH solution. The outcomes from the three-electrode assembly demonstrated that the SnO2-MoS2 composite material yields a high capacitance value of 415 F/g than pure SnO2 and MoS2 electrodes with the lowest resistance values, indicating the fast transportation of ions during the electrochemical process. Inspired by the optimized performance of SnO2-MoS2 composite material, an asymmetric supercapacitor was further developed with GO (graphene oxide) severed as the negative electrode and symbolized as "SnO2-MoS2||GO-KOH asymmetric supercapacitor" in aqueous solution as the electrolyte. Remarkably, a high output voltage of 1.6 V was realized coupled with a high capacitance of 102 F/g, which can be attributed to the combined energy storage performance of pseudocapacitive, and double-layer capacitance arises from SnO2-MoS2 and graphene oxide (GO), respectively. Moreover, a high specific energy of 32 Wh/kg at a maximum specific power of 5520 W/kg was achieved at excellent cycling stability of 92.2 % capacitance retention after 5000 cycles at 10 A/g. Therefore, we summarize that metal oxide can composite with metal oxide, and graphene oxide (GO) collectively boosts the overall performance of high-performance supercapacitors.