In Operando Calorimetric Measurements for Activated Carbon Electrodes in Ionic Liquid Electrolytes under Large Potential Windows
[1];
[2];
[3];
[4];
[4];
[4]
- Univ. of California, Los Angeles, CA (United States); King Fahd Univ. of Petroleum and Minerals (KFUPM), Dhahran (Saudi Arabia)
- Ariel Univ. (Israel); Univ. of California, Los Angeles, CA (United States)
- Univ. of California, Los Angeles, CA (United States)
- Univ. of California, Los Angeles, CA (United States); Univ. of California, Los Angeles, CA (United States). California NanoSystems Inst.
This study aims to investigate the effect of the potential window on heat generation in carbon-based electrical double layer capacitors (EDLCs) with ionic-liquid (IL)-based electrolytes using in operando calorimetry. The EDLCs consisted of two identical activated-carbon electrodes with either neat 1-butyl-1-methylpyrrolidinium bis(trifluoromethane-sulfonyl)imide ([Pyr14][TFSI]) electrolyte or 1.0 m [Pyr14][TFSI] in propylene carbonate (PC) as electrolyte. The instantaneous heat generation rate at each electrode was measured under galvanostatic cycling for different potential windows ranging from 1 to 4 V. First, the heat generation rates at the positive and negative electrodes differed significantly in neat IL owing to the differences in the ion sizes and diffusion coefficients. However, these differences were minimized when the IL was diluted in PC. Second, for EDLC in neat [Pyr14][TFSI] at high potential window (4 V), a pronounced endothermic peak was observed at the beginning of the charging step at the positive electrode owing to TFSI- intercalation in the activated carbon. On the other hand, for EDLC in 1.0 m [Pyr14][TFSI] in PC at potential window above 3 V, an endothermic peak was observed only at the negative electrode owing to the decomposition of PC. Third, for both neat and diluted [Pyr14][TFSI] electrolytes, the irreversible heat generation rate increased with increasing potential window and exceeded Joule heating. This was attributed to the effect of potential-dependent charge redistribution resistance. Additionally, a further increase in the irreversible heat generation rate was observed for the largest potential windows owing to the degradation of the PC solvent. Finally, for both types of electrolyte, the reversible heat generation rate increased with increasing potential window because of the increase in the amount of ion adsorbed/desorbed at the electrode/electrolyte interface.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Synthetic Control Across Length-scales for Advancing Rechargeables (SCALAR); Univ. of California, Los Angeles, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0019381
- OSTI ID:
- 1767534
- Journal Information:
- ChemSusChem, Vol. 13, Issue 5; ISSN 1864-5631
- Publisher:
- ChemPubSoc EuropeCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
electrocatalysis
electrical energy storage
defects
charge transport
mesoscale science
materials and chemistry by design
mesostructured materials
synthesis (novel materials)
synthesis (scalable processing)
activated carbon
electrolyte degradation
ionic liquids
thermal management
thermal runaway