Compositionally Tunable Mn–V–Fe Phosphoselenide Nanorods with Minimal Ion-Diffusion Barrier as High Energy Density Battery Electrode Materials

The design and synthesis of novel heterostructured electrode materials are crucial to enable the fabrication of efficient supercapacitor devices. In this regard, transition metal phosphochalcogenides (S, Se) are promising candidates owing to their exotic electronic properties. Herein, a facile two-step hydrothermal protocol was used to synthesize binary and ternary metal phospho-selenide electrodes (Mn–Fe–P-Se, V–Fe–P-Se, Mn–V–P-Se, and Mn–Fe–V–P-Se). The chemical composition, morphology, and structure of the as-fabricated materials were fully investigated. The three-electrode electrochemical evaluation at 1.0 A g^–1 demonstrated that the ternary metal electrode (MFVP-Se) exhibits a high capacity of 1968.63 C g^–1. To assess the practical value of the rationally designed Mn–Fe–V–P-Se electrode material, Mn–Fe–V–P-Se was used as a positive electrode coupled with activated carbon (AC) as a negative electrode to assemble a hybrid supercapacitor device. This Mn–Fe–V–P-Se//AC device delivers a power density of 1999.96 W kg^–1 with a high energy density of 149.88 Wh kg^–1 coupled with no capacity loss after 5000 charging/discharging cycles. Additionally, density functional theory calculations revealed that our electrode exhibits suitable adsorption energy for OH^– ions with a minimal diffusion barrier for ions.