Abstract
Two-dimensional
electrically conductive metal-organic frameworks (MOFs) are candidate electrode
materials for use in electric double-layer capacitor (EDLC) structure-property
investigations due to their well-defined crystalline structures. Their promising
capacitive performance was first illustrated by EDLCs constructed with the
layered framework Ni3(HITP)2 (HITP = 2,3,6,7,10,11-hexaiminotriphenylene)
and an organic electrolyte. Despite
this promise, there have been few follow-up
studies on the use of these frameworks in EDLCs, raising questions about the
generality of the results. Here, we demonstrate the high capacitive performance of
the layered framework Cu3(HHTP)2 (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene)
in EDLCs with an organic electrolyte and compare its performance with Ni3(HITP)2.
Cu3(HHTP)2 exhibits a specific capacitance of 110
– 114 F g–1 at low current densities of 0.04 – 0.05 A g–1
and shows modest capacitance retentions (66 %) at current densities up to 2 A g–1,
mirroring the performance of Ni3(HITP)2. However, we also
explore the limitations of Cu3(HHTP)2 in EDLCs, finding a
limited cell voltage window of 1.3 V and only moderate capacitance retention over
30,000 cycles. This illustrates that these materials require further
development to improve their EDLC performance, particularly to reach similar cycling
performance levels as porous carbons. Despite this, our work underscores the
utility of framework materials in EDLCs and suggests that capacitive
performance is largely independent of the identity of the metal node and
organic linker molecule, instead being dictated by the three-dimensional
structure of the framework. These important insights will aid the design of
future conductive MOFs for use in EDLCs.
Supplementary materials
Title
Supplementary Information - ChemRxiv
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