MOF/PEDOT/HPMo-based polycomponent hierarchical hollow micro-vesicles for high performance flexible supercapacitors

Abstract

Metal–organic frameworks (MOFs) are promising electrode materials for supercapacitors; however, their electrochemical performances are limited by their low electrical conductivities. To address this problem, “conductive ink” poly(3,4-ethylenedioxythiophene) (PEDOT) was used to enhance the conductivity, while “electron sponge” polyoxometalate [PMo₁₂O₄₀]³⁻ (PMo₁₂) with large electronic transfer capability was used as the capacitance contributor. Finally, MOFs (PCN-224) acted as the host of this composite that provided the electrical double-layer capacitor and a PCN-224@PEDOT/PMo₁₂–CC-II hierarchical hollow micro-vesicle nanostructure was obtained via a simple one-step electro-codeposition. The microvesicle nanocomposite was interspersed in MOF hosts. Benefiting from the novel structure and the synergistic effect of three components, the optimal areal capacitance of the PCN-224@PEDOT/PMo₁₂–CC-II electrode was 4077.8 mF cm⁻² at 5 mA cm⁻² (the concentration ratio of EDOT : PMo₁₂ is 1 : 0.75), which is 32.9 times more than that of pristine PCN-224 (123.6 mF cm⁻²). Furthermore, a symmetric supercapacitor device was constructed by the PCN-224@PEDOT/PMo₁₂–CC-II nanocomposite, which possessed an excellent energy density of 0.297–0.0192 mW h cm⁻² (at a power density of 0.324–5.128 W cm⁻²) and a good long-term cycle ability (84.59% for 10 000 cycles at 5 mA cm⁻²). This study presented a one-step electro-deposition synthetic strategy for the design and fabrication of the high-capacitance MOF-based electrode material, which showed great promise in the future design of high-performance materials for advanced energy production.