Novel Core–Shell‐Structured Zeolitic Imidazolate Framework (ZIF)‐90@ZIF‐67 Applied for High‐Performance All‐Solid‐State Asymmetric Supercapacitor

Herein, a core–shell structured zeolitic imidazolate framework (ZIF)‐90@ZIF‐67 is successfully synthesized with higher specific area and more micropores by a seed epitaxial growth method at room temperature, combining both the advantages of ZIFs and core–shell‐structured materials. When it is applied for supercapacitors’ electrode materials, ZIF‐90@ZIF‐67 delivers the best energy storage ability and excellent electrochemical stability. In a three‐electrode system, its specific capacitance reaches 1357.8 F g −1 at 1 A g −1 and maintains 55.4% while increasing the current density from 1 A g −1 to 20 A g −1 . In a two‐electrode system, an all‐solid‐state asymmetric supercapacitor is assembled using ZIF‐90@ZIF‐67 and activated carbon (CV) as the positive and negative electrode material. The simple device exhibits a high specific capacitance of 151.6 F g −1 at 0.5 A g −1 and a high energy density of 53.9 Wh kg −1 at 510.2 W kg −1 . Surprisingly, the device achieves a specific capacitance retention of 95.8% after 10 000 cycles at 10 A g −1 . Finally, two simple all‐solid‐state supercapacitors in series power a blue lighting‐emitting diode for over 13 min, which reveals that the core–shell ZIF‐90@ZIF‐67 has great potential application prospects in the field of energy storage.