Three-Dimensional Graphene-TiO₂-SnO₂ Ternary Nanocomposites for High-Performance Asymmetric Supercapacitors

Ternary nanocomposites synergistically combine the material characteristics of three materials, altering the desired charge storage properties such as electrical conductivity, redox states, and surface area. Therefore, to improve the energy synergistic of SnO₂, TiO₂, and three-dimensional graphene, herein, we report a facile hydrothermal technique to synthesize a ternary nanocomposite of three-dimensional graphene-tin oxide-titanium dioxide (3DG-SnO₂-TiO₂). The synthesized ternary nanocomposite was characterized using material characterization techniques such as XRD, Raman spectroscopy, FTIR spectroscopy, FESEM, and EDXS. The surface area and porosity of the material were studied using Brunauer-Emmett-Teller (BET) studies. XRD studies showed the crystalline nature of the characteristic peaks of the individual materials, and FESEM studies revealed the deposition of SnO₂-TiO₂ on 3DG. The BET results show that incorporating 3DG into the SnO₂-TiO₂ binary nanocomposite increased its surface area compared to the binary composite. A three-electrode system compared the electrochemical performances of both the binary and ternary composites as a battery-type supercapacitor electrode in different molar KOH (1, 3, and 6 M) electrolytes. It was determined that the ternary nanocomposite electrode in 6 M KOH delivered a maximum specific capacitance of 232.7 C g^-1 at 1 A g^-1. An asymmetric supercapacitor (ASC) was fabricated based on 3DG-SnO₂-TiO₂ as a positive electrode and commercial activated carbon as a negative electrode (3DG-SnO₂-TiO₂//AC). The ASC delivered a maximum energy density of 28.6 Wh kg^-1 at a power density of 367.7 W kg^-1. Furthermore, the device delivered a superior cycling stability of ∼97% after 5000 cycles, showing its prospects as a commercial ASC electrode.