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Li⁺ and Oxidant Addition To Control Ionic and Electronic Conduction in Ionic Liquid-Functionalized Conjugated Polymers

Rawlings, Dakota and Lee, Dongwook and Kim, Jeongmin and Magdău, Ioan-Bogdan and Pace, Gordon and Richardson, Peter M. and Thomas, Elayne M. and Danielsen, Scott P. O. and Tolbert, Sarah H. and Miller, Thomas F., III and Seshadri, Ram and Segalman, Rachel A. (2021) Li⁺ and Oxidant Addition To Control Ionic and Electronic Conduction in Ionic Liquid-Functionalized Conjugated Polymers. Chemistry of Materials, 33 (16). pp. 6464-6474. ISSN 0897-4756. doi:10.1021/acs.chemmater.1c01811.

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Conduction of ions and charge (electrons) often follow distinct materials design rules, presenting a significant challenge for the development of homogeneous materials that are good at both. The fundamental interactions that dictate ionic and electronic conduction in mixed conductors are still unclear. Here, we characterize the ionic and electronic conduction of a class of mixed polymeric conductors in which ionic liquid groups are tethered to an electron-conducting conjugated polymer backbone. A model conjugated polymeric ionic liquid, poly{3-[6′-(N-methylimidazolium)hexyl]thiophene}BF₄⁻ (P3HT-IM), is synthesized and shown to have significant long-range ordering. Chemical oxidation of the polymer results in a room-temperature electronic conductivity of 10⁻² S cm⁻¹. The polymer is also capable of dissolving Li⁺ salt up to a concentration of r_(salt) = 1 [moles of salt]/[moles of monomer]. The polymer displays a monotonic increase in ionic conductivity with salt concentration, reaching a maximum room-temperature ionic conductivity of 10⁻⁵ S cm⁻¹ at the highest concentration of r_(salt) = 1. Notably, this is among the first studies to characterize both ionic conductivity and electronic conductivity of an ionic liquid-functionalized conjugated polymer upon the addition of an oxidant and salt. All-atom molecular dynamics (MD) simulations indicate that the imidazolium side chains promote the formation of a percolated network of solvation sites at high salt concentrations, which facilitates ion transport. Pulsed-field gradient nuclear magnetic resonance diffusivity measurements and MD indicate a lithium transference number around 0.5, suggesting that the percolated solvation network promotes lithium transport in a way that is unique from many ion-conducting systems. These results suggest that the addition of diffuse, ionic liquid-like groups to a conjugated polymer backbone serves as an effective design approach to facilitate simultaneous lithium-ion conduction and electronic conduction in the absence of a solvent.

Item Type:Article
Related URLs:
URLURL TypeDescription
Magdău, Ioan-Bogdan0000-0002-3963-5076
Richardson, Peter M.0000-0002-6631-2459
Thomas, Elayne M.0000-0003-0072-4204
Danielsen, Scott P. O.0000-0003-3432-5578
Tolbert, Sarah H.0000-0001-9969-1582
Miller, Thomas F., III0000-0002-1882-5380
Seshadri, Ram0000-0001-5858-4027
Segalman, Rachel A.0000-0002-4292-5103
Alternate Title:Li+ and Oxidant Addition To Control Ionic and Electronic Conduction in Ionic Liquid-Functionalized Conjugated Polymers
Additional Information:© 2021 American Chemical Society. Received 26 May 2021; Revised 27 July 2021; Published online 6 August 2021; Published in issue 24 August 2021. We gratefully acknowledge the Center for Synthetic Control Across Length-Scales for Advancing Rechargeables (SCALAR), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award #DE-SC0019381, for support of device fabrication, simulations, and materials characterization. D.R. gratefully acknowledges support from the Department of Energy Office of Basic Energy Sciences (DE-SC0016390) for polymer synthesis. The research reported here made use of shared facilities of the National Science Foundation Materials Research Science and Engineering Center (MRSEC) at UC Santa Barbara (NSF DMR 1720256), which is a member of the Materials Research Facilities Network ( This research used X-ray scattering resources (NSLS-II, beamline 11-BM, Brookhaven National Laboratory) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. G.T.P. gratefully acknowledges support from the National Science Foundation Graduate Research Fellowship Program under Grant No. 1650114. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The authors declare no competing financial interest.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0019381
Department of Energy (DOE)DE-SC0016390
Department of Energy (DOE)DE-SC0012704
NSF Graduate Research FellowshipDGE-1650114
Subject Keywords:Salts, Electrical conductivity, Conjugated polymers, Ions, Polymers
Issue or Number:16
Record Number:CaltechAUTHORS:20210830-230029193
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Official Citation:Li+ and Oxidant Addition To Control Ionic and Electronic Conduction in Ionic Liquid-Functionalized Conjugated Polymers Dakota Rawlings, Dongwook Lee, Jeongmin Kim, Ioan-Bogdan Magdău, Gordon Pace, Peter M. Richardson, Elayne M. Thomas, Scott P. O. Danielsen, Sarah H. Tolbert, Thomas F. Miller, Ram Seshadri, and Rachel A. Segalman Chemistry of Materials 2021 33 (16), 6464-6474 DOI: 10.1021/acs.chemmater.1c01811
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110631
Deposited By: George Porter
Deposited On:31 Aug 2021 14:33
Last Modified:31 Aug 2021 14:33

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