Bi Sheng, Banda Harish, Chen Ming, Niu Liang, Chen Mingyu, Wu Taizheng, Wang Jiasheng, Wang Runxi, Feng Jiamao, Chen Tianyang, Dincă Mircea, Kornyshev Alexei A, Feng Guang
State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan, China.
Department of Chemistry, Faculty of Natural Sciences, Imperial College London, London, UK.
Nat Mater. 2020 May;19(5):552-558. doi: 10.1038/s41563-019-0598-7. Epub 2020 Feb 3.
We performed constant-potential molecular dynamics simulations to analyse the double-layer structure and capacitive performance of supercapacitors composed of conductive metal-organic framework (MOF) electrodes and ionic liquids. The molecular modelling clarifies how ions transport and reside inside polarized porous MOFs, and then predicts the corresponding potential-dependent capacitance in characteristic shapes. The transmission line model was adopted to characterize the charging dynamics, which further allowed evaluation of the capacitive performance of this class of supercapacitors at the macroscale from the simulation-obtained data at the nanoscale. These 'computational microscopy' results were supported by macroscopic electrochemical measurements. Such a combined nanoscale-to-macroscale investigation demonstrates the potential of MOF supercapacitors for achieving unprecedentedly high volumetric energy and power densities. It gives molecular insights into preferred structures of MOFs for accomplishing consistent performance with optimal energy-power balance, providing a blueprint for future characterization and design of these new supercapacitor systems.
我们进行了恒电位分子动力学模拟，以分析由导电金属有机框架（MOF）电极和离子液体组成的超级电容器的双层结构和电容性能。分子建模阐明了离子如何在极化多孔MOF内部传输和驻留，然后预测了具有特征形状的相应电位依赖性电容。采用传输线模型来表征充电动力学，这进一步使得能够根据纳米尺度的模拟数据在宏观尺度上评估这类超级电容器的电容性能。这些“计算显微镜”结果得到了宏观电化学测量的支持。这种从纳米尺度到宏观尺度的联合研究证明了MOF超级电容器在实现前所未有的高体积能量和功率密度方面的潜力。它为实现具有最佳能量-功率平衡的一致性能的MOF优选结构提供了分子层面的见解，为这些新型超级电容器系统的未来表征和设计提供了蓝图。
