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A nonaqueous potassium-ion hybrid capacitor enabled by two-dimensional diffusion pathways of dipotassium terephthalate

Nonaqueous potassium-ion hybrid capacitors (KIHCs) are faced with limited redox reaction kinetics of electrodes for accommodation of large-sized K(+). Here, dipotassium terephthalate (K(2)TP) is applied as an organic negative electrode to provide comparable reaction kinetics with a non-faradaic acti...

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Detalles Bibliográficos
Autores principales: Luo, Yuwen, Liu, Luojia, Lei, Kaixiang, Shi, Jifu, Xu, Gang, Li, Fujun, Chen, Jun
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6375359/
https://www.ncbi.nlm.nih.gov/pubmed/30842862
http://dx.doi.org/10.1039/c8sc04489a
Descripción
Sumario:Nonaqueous potassium-ion hybrid capacitors (KIHCs) are faced with limited redox reaction kinetics of electrodes for accommodation of large-sized K(+). Here, dipotassium terephthalate (K(2)TP) is applied as an organic negative electrode to provide comparable reaction kinetics with a non-faradaic activated carbon (AC) positive electrode to boost the electrochemical performance of KIHCs. It is revealed that the large exchange current density and fast two-dimensional (2D) diffusion pathways of K(+) in K(2)TP determined by density functional theory (DFT) calculations ensure its fast redox reaction and transport kinetics. The as-constructed KIHC presents both high energy and power densities of 101 W h kg(–1) and 2160 W kg(–1) based on the mass of the two electrodes (41.5 W h kg(–1) and 885.2 W kg(–1) based on the mass of the two electrodes and electrolyte), respectively, and a superior capacity retention of 97.7% after 500 cycles. The excellent electrochemical performance is attributed to the fast kinetics, good structural flexibility, and small volume change (9.4%) of K(2)TP upon K(+) insertion/extraction, and its good compatibility with the AC positive electrode in 1,2-dimethoxyethane (DME)-based electrolyte. This will promote application of organic materials in hybrid capacitors and the development of KIHCs.