Tetrahydroxy-anthraquinone induced structural change of zeolitic imidazolate frameworks for asymmetric supercapacitor electrode material application

A novel tetrahydroxy-anthraquinone zeolitic framework (TZM) with a Viburnum blossom-like structure is synthesized via a simple solvothermal method by using tetrahydroxy-anthraquinone to substitute imidazolate without carbonization at high temperature. Considering the excellent electrochemical performance of the TZM, including a high specific capacitance of 2030 F g at a current density of 1 A g, and good cycling stability with a capacitance retention of 94% of the initial capacitance after 1000 cycling charge/discharge measurements, an aqueous TZM//AC asymmetric supercapacitor (ASC) in 1 M KOH electrolyte is successfully fabricated by using the resultant TZM as the positive electrode and activated carbon nanosheets (ACS) as the negative electrode, respectively. The as-assembled aqueous ASC delivers a high energy density of 47.7 W h kg at a power density of 750 W kg with a high potential window of 0-1.5 V. Moreover, for the purpose of exploring the practical application of the active materials, an all-solid-state ASC TZM//ACS device with PVA-KOH gel electrolyte and separator is assembled and connected, which can light up a red light-emitting diode (LED). Its good performance demonstrates that the TZM//ACS ASC is a promising energy-storage system.