Polyoxometalate‐Based Metal‐Organic Framework/Polypyrrole Composites toward Enhanced Supercapacitor Performance

Abstract Supercapacitors are energy storage equipment that have attracted particular attention owing to its wide operating temperature range, high‐power density, and small size, whereas the limited energy density has always been a main obstacle in many applications. Composite materials have a forward‐looking application value in the manufacture of innovative supercapacitors due to the synergistic effect between various components. We propose a plain oxidative polymerization method to prepare the polyoxometalate‐based metal‐organic framework/polypyrrole composites (PW 12 @MIL‐101/PPy‐n, n represents the volumes of pyrrole) toward supercapacitor electrodes for the first time. PW 12 @MIL‐101 possesses rich and fully accessible active sites as well as regular porosity provided by PW 12 and MIL‐101(Fe), respectively. PPy can effectively meliorate the conductivity of PW 12 @MIL‐101 by accelerating the Faradaic process at the surface, and then facilitate electron/ion transfer between PW 12 @MIL‐101 nanocrystallines. As a result, PW 12 @MIL‐101/PPy‐0.15 composite has a noticeably higher specific capacitance (1217 mF ⋅ cm −2 ), which is better than PW 12 @MIL‐101 (158 mF ⋅ cm −2 ) and MIL‐101 (117 mF ⋅ cm −2 ). Meanwhile, the relevant symmetric supercapacitor assembled with PW 12 @MIL‐101/PPy‐0.15 displays a sizable energy density of 20.7 Wh/kg at a power density of 277.6 W/kg. About 83.7 % of the pristine capacitance is still reserved after 2000 consecutive charges and discharges.