Promoting the energy storage capability via selenium-enriched nickel bismuth selenide/graphite composites as the positive and negative electrodes

Hybrid metal chalcogenides incorporating prolific redox-active transition metal selenides with optimized interactions are suitable candidates to boost the electrochemical properties of supercapacitors. The present study elaborates the design and application of selenium (Se)-enriched reduced graphene oxide hybridized heterostructured nickel bismuth selenide (RGO/Ni-Bi-Se) and bismuth selenide (RGO/Bi2Se3)-based electrode materials by a simple in-situ growth solvothermal reaction for advanced battery-type supercapacitors. Integrating the advantages of different components, good electrical conductivity of RGO and Se-enrichment induce a strong collaborative effect on redox reactions. The favourable structural and compositional features are not only desirable for the capacitive and rate performance enhancement but also for volume change mitigation during successive charge–discharge processes. The heterostructured RGO/Ni-Bi-Se delivers a boosted electrochemical behavior with an exceptional specific capacity (220.2 mAh g–1 at 1 A g–1) and good rate performance (54.8% capacity retention at 50 A g–1). The strong synergy between the Ni and Bi active components with multielectron reversible Faradic redox reactions optimizes the overall electrochemical performances and modifies the charge storage capability of the electrode material. The interconnected porous nanoarchitectures are regulated with abundant interface engineering and disorders, thereby achieving a large electrode/electrolyte area at junction and shortening the ion diffusion paths as well as accelerating the electron-transmission ability during operation. On the other hand, the as-obtained RGO/Bi2Se3 negative electrode material exhibits better pseudocapacitive properties with favourable reversibility and displays a large specific capacitance of 464 F g–1 at 1 A g–1. The RGO fabric not only offers a solid skeleton for the self-assembly of building units but also enlarges the specific area for more electrochemical active sites and decreases the charge transfer resistance. The formation of weak electronegative Se is profitable to adjust the electronic configuration of exposed Ni/Bi sites. More significantly, the heterostructured RGO/Ni-Bi-Se reveals a well-matched performance with the capacitive RGO/Bi2Se3 and the established aqueous battery supercapacitor hybrid (BSH) device achieves admirable energy density of 62.3 Wh kg−1 at a power density of 949.7 W kg−1 together with 89.2% retention after 10 000 cycles.