A High-Capacity Negative Electrode for Asymmetric Supercapacitors Based on a PMo12Coordination Polymer with Novel Water-Assisted Proton Channels

The development of a negative electrode for supercapacitors is a critical challenge for the next-generation of energy-storage devices. Herein, two new electrodes formed by the coordination polymers [Ni(itmb)(4)(HPMo12O40)]center dot 2H(2)O (1) and [Zn(itmb)(3)(H2O)(HPMo12O40)]center dot 4H(2)O (2) (itmb = 1-(imidazo-1-ly)-4-(1,2,4-triazol-1-ylmethyl)benzene), synthesized by a simple hydrothermal method, are described. Compounds1and2show high capacitances of 477.9 and 890.2 F g(-1), respectively. An asymmetric supercapacitor device assembled using2which has novel water-assisted proton channels as negative electrode and active carbon as positive electrode shows ultrahigh energy density and power density of 23.4 W h kg(-1)and 3864.4 W kg(-1), respectively. Moreover, the ability to feed a red light emitting diode (LED) also demonstrates the feasibility for practical use. The results allow a better elucidation of the storage mechanism in polyoxometalate-based coordination polymers and provide a promising direction for exploring novel negative materials for new-generation high-performance supercapacitors.