Intercalated metal–organic frameworks with high electronic conductivity as negative electrode materials for hybrid capacitors. Issue 1 (December 2018)

• Record Type: Journal Article
• Authors: Ozawa, Yuka; Ogihara, Nobuhiro; Hasegawa, Masaki; Hiruta, Osamu; Ohba, Nobuko; Kishida, Yoshihiro
• Is Part Of: Communications chemistry. Volume 1:Issue 1(2018)
• Page Start: 1
• Page End: 11
• Publication Date: 2018-12
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1038/s42004-018-0064-5
• Languages: English
• ISSNs: 2399-3669

Abstract

Abstract Hybrid capacitors should ideally exhibit high volumetric energy density, favorable low-temperature performance and safe operation. Here we describe a negative electrode comprising an intercalated metal–organic framework, 4, 4′-biphenyl dicarboxylate dilithium [4, 4′-Bph(COOLi)2 ], which forms a repeating organic–inorganic layered structure of π-stacked biphenyl and tetrahedral LiO4 units. The electrode shows a stepwise two-electron transfer and has a capacity of 190 mAh g−1 at 0.7 V vs. Li/Li+, which can suppress the lithium metal deposition reaction occurring an internal short circuit. A hybrid capacitor containing 4, 4′-Bph(COOLi)2 negative and activated carbon positive electrodes possesses high volumetric energy density of approximately 60 Wh L−1 and good high-rate performance, particularly at the low temperature of 0 °C, because of low charge-transfer resistance along with low activation energy. Hopping mobility calculations suggest the observed low resistance properties are the result of high electron mobility arising from two electron-hopping pathways between adjacent molecules in the π-stacked biphenyl packing layer by lithium intercalation. Intercalated metal-organic frameworks hold promising potential as supercapacitors. Here the performance of 4, 4′-biphenyl dicarboxylate dilithium is explored using both experimental and computational methods, offering insight into the basis for high electron and lithium-ion conduction in this material.