Phase-Engineered Tin Sulfides and Their Heterostructure with Ti₃C₂T_x MXene for All-Solid-State Flexible Asymmetric Supercapacitors

Despite supercapacitors’ high-power density and rapid charge transfer, limitations in energy density and stability drive research into cost-effective, efficient electrode materials. Emerging two-dimensional materials, especially transition metal sulfides, are of significant interest due to their tunable properties. Strategies such as phase engineering, defect creation, heterostructure formation, and advanced synthesis methods refine the electrochemical properties. In this study, different phases of tin sulfide, including α-SnS, π-SnS, and β-SnS, were effectively synthesized through hydrothermal and wet chemical methodologies. Following comprehensive characterization, electrochemical analysis offered valuable insights into the electrochemical behavior of each phase, notably showcasing superior performance in β-SnS to α-SnS and π-SnS. To further augment the electrochemical capabilities of β-SnS, a heterostructure was synthesized incorporating Ti 3 C 2 T x MXene. The heterostructure displayed an exceptional capacitance of 615 mF/cm 2 at a flow rate of 4 mA/cm 2 . This heterostructure was then employed in fabricating an asymmetric supercapacitor (β-SnS/Ti 3 C 2 T x //Ti 3 C 2 T x ) operated at 1.5 V, displaying a high areal capacitance of 109 mF/cm 2 along with the energy density and power density of 34.06 μWh/cm 2 and 6.28 mW/cm 2, respectively. With amazing cycling stability, the electrochemical performance and structural properties were corroborated through density functional theoretical simulations.