Advances in Graphene-Transition Metal Selenides Hybrid Materials for High-Performance Supercapacitors: A Review.

Supercapacitors have attracted significant attention as energy storage devices due to their high power density, rapid charge-discharge capability, and long cycle life. Their performance is primarily influenced by electrode materials, electrolytes, and operational voltage windows. Among these, the development of advanced electrode materials is crucial for enhancing energy density, specific capacitance, and cyclic stability. This review focuses on recent advancements in graphene-based hybrid materials, particularly their integration with transition metal selenides (TMSs) for supercapacitor applications. Combining graphene and its derivatives with TMSs, which possess multiple oxidation states and high theoretical capacitance, results in hybrids with superior electrochemical performance. Studies show that these materials achieve higher specific capacitance, energy density, and power density compared to graphene composites with carbides, nitrides, phosphides, and oxides. Key findings include synthesis strategies, structural modifications, and electrochemical properties of graphene-TMS hybrids. Notably, these hybrids have demonstrated specific capacitances exceeding 3105 F/g at 1 A/g, power densities up to 5597.77 W/kg, and energy densities reaching 126.3 Wh/kg, making them highly promising for next-generation supercapacitors. This review critically evaluates the current state-of-the-art, explores the synergistic effects between graphene and TMSs, such as improved charge transfer kinetics and structural stability, and identifies challenges and future directions in graphene-TMS hybrid supercapacitors.