A SnO/MXene hybrid nanocomposite as a negative electrode material for asymmetric supercapacitors

In this report, we synthesised a SnO 2 /Ti 3 C 2 T x composite through a single-step hydrothermal route with varying quantities of Ti 3 C 2 T x (from 50 mg to 100 mg). The formation of a hybrid increases the interlayer spacing of Ti 3 C 2 T x , and this increment in the interlayer spacing supports the charge transport in the electroactive material. Thus, the resultant composite with 80 mg of Ti 3 C 2 T x (SnO 2 /Ti 3 C 2 T x -80) displays a specific capacitance of 620 F g −1 at 2 A g −1 current density. Density Functional Theory (DFT) calculations have been performed to comprehend the structural and electronic properties of SnO 2 and hybrid SnO 2 /Ti 3 C 2 T x systems. The formation of a hybrid structure has significantly increased the conductivity of the SnO 2 system due to the charge transfer from Ti 3 C 2 T x to SnO 2 . The quantum capacitance is higher in the hybrid system than in the pristine SnO 2 system. This validates and supports our experimental results that the hybrid system has enhanced charge storage performance. For practical realisation, an asymmetric supercapacitor (ASC) device is fabricated using SnO 2 /Ti 3 C 2 T x -80 as a negative electroactive material and cobalt phosphate as a positive electroactive material. The fabricated device delivers a specific capacitance of 100 F g −1 at 3 A g −1 current density. The ASC shows an energy density of 32 W h kg −1 with a power density of 5118.5 W kg −1 . The device retains 93% of its initial capacitance even after 15 000 GCD cycles at 4.5 A g −1 with a coulombic efficiency of 98%. A tin oxide/MXene hybrid (SnO 2 /Ti 3 C 2 T x -80) was synthesized by a single step hydrothermal route and used as a negative electrode towards the fabrication of an asymmetric supercapacitor.