POMCPs with Novel Two Water‐Assisted Proton Channels Accommodated by MXenes for Asymmetric Supercapacitors

Abstract To develop high‐performance supercapacitors, the negative electrode is at present viewed as one of the most challenging tasks for obtaining the next‐generation of energy storage devices. Therefore, in this study, a polyoxometalate‐based coordination polymer [Zn(itmb) 3 H 2 O][H 2 SiW 12 O 40 ]·5H 2 O ( 1 ) is designed and prepared by a simple hydrothermal method for constructing a high‐capacity negative electrode. Polymer 1 has two water‐assisted proton channels, which are conducive to enhancing the electrical conductivity and storage capacity. Then, MXene Ti 3 C 2 T x is chosen to accommodate coordination polymer 1 as the interlayer spacers to improve the conductivity and cycling stability of 1 , while preventing the restacking of MXene. Expectedly, the produced composite electrode 1 @Ti 3 C 2 T x shows an excellent specific capacitance (1480.1 F g −1 at 5 A g −1 ) and high rate performance (a capacity retention of 71.5% from 5 to 20 A g −1 ). Consequently, an asymmetric supercapacitor device is fabricated using 1 @Ti 3 C 2 T x as the negative electrode and celtuce leaves‐derived carbon paper as the positive electrode, which demonstrates ultrahigh energy density of 32.2 Wh kg −1 , and power density 2397.5 W kg −1 , respectively. In addition, the ability to illuminate a red light‐emitting diode for several minutes validates its feasibility for practical application.