Ni₆Se₅, an unexplored transition metal chalcogenide of formula M_(n+1)X _n(2 ≤ n≤ 8), for high-performance hybrid supercapacitor and Li-ion battery application

This work reports anin situ, one-step hydrothermal preparation procedure of a binder-free electrode growth of Ni₆Se₅on nickel foam (Ni₆Se₅/NF) with a rod-like structure. Ni₆Se₅is an enveloped transition metal chalcogenides of formula M_(n+1)X_n(where 2 ≤n≤ 8, M is a transition metal and X is chalcogen) of the nickel selenide family. The Ni₆Se₅/NF electrode described here demonstrates an exceptional lifetime of 81% capacitance retention over 20000 cycles and a high specific capacitance of 473.5 Fg^-1at a current density of 4 Ag^-1. The Ni₆Se₅/NF/activated carbon asymmetric supercapacitor (SC) exhibits a remarkable 97.3 Whkg^-1energy density and a 2325 Wkg^-1power density. Ni₆Se₅served as an active electrode material in SC applications and offered exceptional power density and long cycle life. Ni₆Se₅/NF, used as an anode for Li-ion batteries, has a lithium storage capacity of 939.7 mAhg^-1at 100 mAg^-1current density. Ni₆Se₅'s (active electrode material) excellent energy storage capability, which was previously unreported, is particularly beneficial for electrochemical energy storage device applications.