Phosphorization Engineering on Metal–Organic Frameworks for Quasi‐Solid‐State Asymmetry Supercapacitors

Porous carbon and metal oxides/sulfides prepared by using metal-organic frameworks (MOFs) as the precursors have been widely applied to the realm of supercapacitors. However, employing MOF-derived metal phosphides as positive and negative electrode materials for supercapacitors has scarcely been reported thus far. Herein, two types of MOFs are used as the precursors to prepare CoP and FeP₄ nanocubes through a two-step controllable heat treatment process. Due to the advantages of composition and structure, the specific capacitances of FeP₄ and CoP nanocubes reach 345 and 600 F g^-1 at the current density of 1 A g^-1 , respectively. Moreover, a quasi-solid-state asymmetric supercapacitor is assembled based on charge matching principle by employing CoP and FeP₄ nanocubes as the positive and negative electrodes, respectively, which exhibits a high energy density of 46.38 Wh kg^-1 at the power density of 695 W kg^-1 . Furthermore, a solar-charging power system is assembled by combining the quasi-solid-state asymmetric supercapacitor and monocrystalline silicon plates, substantiating that the device can power the toy electric fan. This work paves a practical way toward the rational design of quasi-solid-state asymmetry supercapacitors systems affording favorable energy density and long lifespan.