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Nonstoichiometric triazolium protic ionic liquids for all-organic batteries

Karlsson, Christoffer LU ; Strietzel, Christian; Huang, Hao; Sjödin, Martin and Jannasch, Patric LU (2018) In ACS Applied Energy Materials 1(11). p.6451-6462
Abstract
Non stoichiometric protic ionic liquids (NSPILs) are efficient electrolytes for protic electrochemical devices such as the all-organic proton battery, which has been suggested as a sustainable approach to energy storage. NSPILs contain a mixture of proton donors and acceptors and are ideal for this purpose due to their high proton conductivity, high electrochemical stability, low cost and ease of synthesis. The electrolyte proton activity must be controlled carefully in these devices since it greatly influences the kinetics and energetics of the electrode redox reactions, and hence also impacts battery device performance. In this study, specific NSPILs were designed and evaluated as electrolytes for the all-organic proton battery. The... (More)
Non stoichiometric protic ionic liquids (NSPILs) are efficient electrolytes for protic electrochemical devices such as the all-organic proton battery, which has been suggested as a sustainable approach to energy storage. NSPILs contain a mixture of proton donors and acceptors and are ideal for this purpose due to their high proton conductivity, high electrochemical stability, low cost and ease of synthesis. The electrolyte proton activity must be controlled carefully in these devices since it greatly influences the kinetics and energetics of the electrode redox reactions, and hence also impacts battery device performance. In this study, specific NSPILs were designed and evaluated as electrolytes for the all-organic proton battery. The NSPILs were based on either 1,2,4-triazole or 1-methyl-1,2,4-triazole partially protonated with bis(trifluoromethylsulfonyl)imide (TFSI) to produce a range of NSPILs with different degrees of protonation. Both types of NSPIL investigated here exhibit a maximum observed conductivity of 1.2 S/cm (at 120 and 70 °C, respectively), and the eutectic composition of 1-methyl-1,2,4-triazolium TFSI also has high conductivity at 25 °C (24.9 mS/cm), superior to e.g. imidazolium TFSI NSPILs. Pulsed field gradient NMR in conjunction with electrochemical impedance spectroscopy showed that the conductivity originated mainly from vehicle diffusion and proton hopping. Quinone functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes exhibited reversible, fast and stable redox conversion in these electrolytes, and a model is suggested to determine proton activities of NSPILs based on the quinone formal potential. An all-organic proton battery cell was assembled to demonstrate the usefulness of these electrolytes in devices. Fast and complete redox conversion with a cell potential of 0.45 V was demonstrated, even up to scan rates corresponding to 140 C. Compared to the pyridine based electrolytes used for the all-organic proton battery up until now, the present electrolytes display several advantages including lower melting point, lower toxicity, and compatibility with plastic materials. (Less)
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author
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publishing date
type
Contribution to journal
publication status
published
subject
in
ACS Applied Energy Materials
volume
1
issue
11
pages
12 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85064845606
ISSN
2574-0962
DOI
10.1021/acsaem.8b01389
language
English
LU publication?
yes
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dbf15199-08d1-4d59-82cf-3dfbfddbf9b3
date added to LUP
2018-10-24 10:23:31
date last changed
2019-11-13 05:18:41
@article{dbf15199-08d1-4d59-82cf-3dfbfddbf9b3,
  abstract     = {Non stoichiometric protic ionic liquids (NSPILs) are efficient electrolytes for protic electrochemical devices such as the all-organic proton battery, which has been suggested as a sustainable approach to energy storage. NSPILs contain a mixture of proton donors and acceptors and are ideal for this purpose due to their high proton conductivity, high electrochemical stability, low cost and ease of synthesis. The electrolyte proton activity must be controlled carefully in these devices since it greatly influences the kinetics and energetics of the electrode redox reactions, and hence also impacts battery device performance. In this study, specific NSPILs were designed and evaluated as electrolytes for the all-organic proton battery. The NSPILs were based on either 1,2,4-triazole or 1-methyl-1,2,4-triazole partially protonated with bis(trifluoromethylsulfonyl)imide (TFSI) to produce a range of NSPILs with different degrees of protonation. Both types of NSPIL investigated here exhibit a maximum observed conductivity of 1.2 S/cm (at 120 and 70 °C, respectively), and the eutectic composition of 1-methyl-1,2,4-triazolium TFSI also has high conductivity at 25 °C (24.9 mS/cm), superior to e.g. imidazolium TFSI NSPILs. Pulsed field gradient NMR in conjunction with electrochemical impedance spectroscopy showed that the conductivity originated mainly from vehicle diffusion and proton hopping. Quinone functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes exhibited reversible, fast and stable redox conversion in these electrolytes, and a model is suggested to determine proton activities of NSPILs based on the quinone formal potential. An all-organic proton battery cell was assembled to demonstrate the usefulness of these electrolytes in devices. Fast and complete redox conversion with a cell potential of 0.45 V was demonstrated, even up to scan rates corresponding to 140 C. Compared to the pyridine based electrolytes used for the all-organic proton battery up until now, the present electrolytes display several advantages including lower melting point, lower toxicity, and compatibility with plastic materials.},
  author       = {Karlsson, Christoffer and Strietzel, Christian and Huang, Hao and Sjödin, Martin and Jannasch, Patric},
  issn         = {2574-0962},
  language     = {eng},
  number       = {11},
  pages        = {6451--6462},
  publisher    = {The American Chemical Society (ACS)},
  series       = {ACS Applied Energy Materials},
  title        = {Nonstoichiometric triazolium protic ionic liquids for all-organic batteries},
  url          = {http://dx.doi.org/10.1021/acsaem.8b01389},
  volume       = {1},
  year         = {2018},
}