期刊
ADVANCED ENERGY MATERIALS
卷 11, 期 13, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/aenm.202003626
关键词
covalent organic frameworks; polyiodide; redox electrolytes; solid‐ state capacitors; supercapacitors
类别
资金
- IISER-Pune
- DST [DST/TMD/MES/2k17/103]
- DST-Nanomission under the Thematic Unit Program [EMR/2016/003553]
- DST-Inspire
- SERB (EMR/2016)
- MHRD-FAST
- IUSSTF program
Capacitors with microporous electrodes show enhanced Faradaic pseudo-activity, especially when combined with a composite covalent organic framework (COF)-carbon electrode with redox-active KI. The inclusion of KI in H2SO4 electrolyte significantly increases the gravimetric specific capacitance of solid-state capacitors, while the imine-COF maintains 89% capacity even after 10,000 cycles of operation.
Capacitors are the most practical high-storage and rapid charge-release devices. The number of ions stored per unit area and their interaction strength with the electrode dictates capacitor-performance. Microporous materials provide a high storage surface and optimal interactions. Adsorbing electron-rich and easily polarizable molecules into microporous electrodes is expected to boost Faradaic pseudo-activity. If such electrode-electrolyte interactions can be made as a potential-driven reversible process, the resulting capacitors would be adaptable and device-friendly. A composite covalent organic framework (COF)-carbon electrode with redox-active KI is combined in an H2SO4 electrolyte for the first time. This composite electrode benefits from the redox-functionality of COF and electronic conductivity of carbon, leading to superior capacitative activity. Operando spectro-electrochemical measurements reveal the existence of multiple polyiodide species, although the I-3(-) is the predominantly electroactive species adsorbing on the microporous triazine-phenol COF electrode. A systematic fabrication of the flexible solid-state devices using the COF-redox-electrolyte reveals a high areal capacitance of 270 +/- 11 mF cm(-2) and gravimetric capacitance of 57 +/- 8 F g(-1). The inclusion of KI in H2SO4 (electrolyte) yields an approximately eight-fold enhancement in solid-state gravimetric specific capacitance. The imine-COF retains 89% of its capacity even after 10 000 cycles.
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