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The effect of ionic aggregates on the transport of charged species in lithium electrolyte solutions

The effect of ionic aggregates on the transport of charged species in lithium electrolyte solutions
The effect of ionic aggregates on the transport of charged species in lithium electrolyte solutions
In this investigation we focus on the problem of modelling the transport of the charged species (lithium ions) in electrolyte solutions with moderate and high salt concentrations (0.1M to >2M), and consider the Nernst-Planck equation as a model of such processes. First, using a combination of magnetic resonance imaging (MRI) and inverse modelling (IM) we demonstrate that at higher concentrations the Nernst- Planck equation requires negative transference numbers in order to accurately describe the concentration profiles obtained from experiments. The need for such a physically inconsistent constitutive relation indicates the loss of validity of the Nernst-Planck equation as a model for this process. Next we consider the formation of ion pairs and clusters as a possible effect responsible for the appearance of negative transference numbers and derive an extended version of the Nernst-Planck system which accounts for these additional species. However, a careful analysis of this model reveals that incorporation of ion-pairing effects into the modelling will not change the transference numbers inferred from the experimental data via inverse modelling. This demonstrates that physical effects other than formation of ion pairs and clusters must be incorporated into the Nernst-Planck model in order for it to correctly describe ion transport at higher salt concentrations. One prime candidate for such effects is the motion of the reaction surface resulting from dendrite growth.
0013-4651
H561-H567
Richardson, Giles
3fd8e08f-e615-42bb-a1ff-3346c5847b91
Foster, Jamie M.
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Sethurajan, Athinthra
61ef0e2b-7ddd-4ee9-99fe-aee30c474d0e
Krachkovskiy, Sergey
b9052068-ca3f-4a00-ad17-d91359ac24dc
Halalay, Ion
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Goward, Gillian
1c790d64-44d8-400f-81b7-417e2770b2c8
Protas, Bartosz
6eaf58f4-b584-498a-af16-cd2c3f1f289e
Richardson, Giles
3fd8e08f-e615-42bb-a1ff-3346c5847b91
Foster, Jamie M.
7cf00fd5-1568-4021-b15f-7e6aeb7cce2f
Sethurajan, Athinthra
61ef0e2b-7ddd-4ee9-99fe-aee30c474d0e
Krachkovskiy, Sergey
b9052068-ca3f-4a00-ad17-d91359ac24dc
Halalay, Ion
fd5d988a-dd40-4dd2-bd44-95880feb50ba
Goward, Gillian
1c790d64-44d8-400f-81b7-417e2770b2c8
Protas, Bartosz
6eaf58f4-b584-498a-af16-cd2c3f1f289e

Richardson, Giles, Foster, Jamie M., Sethurajan, Athinthra, Krachkovskiy, Sergey, Halalay, Ion, Goward, Gillian and Protas, Bartosz (2018) The effect of ionic aggregates on the transport of charged species in lithium electrolyte solutions. Journal of the Electrochemical Society, 165 (9), H561-H567. (doi:10.1149/2.0981809jes).

Record type: Article

Abstract

In this investigation we focus on the problem of modelling the transport of the charged species (lithium ions) in electrolyte solutions with moderate and high salt concentrations (0.1M to >2M), and consider the Nernst-Planck equation as a model of such processes. First, using a combination of magnetic resonance imaging (MRI) and inverse modelling (IM) we demonstrate that at higher concentrations the Nernst- Planck equation requires negative transference numbers in order to accurately describe the concentration profiles obtained from experiments. The need for such a physically inconsistent constitutive relation indicates the loss of validity of the Nernst-Planck equation as a model for this process. Next we consider the formation of ion pairs and clusters as a possible effect responsible for the appearance of negative transference numbers and derive an extended version of the Nernst-Planck system which accounts for these additional species. However, a careful analysis of this model reveals that incorporation of ion-pairing effects into the modelling will not change the transference numbers inferred from the experimental data via inverse modelling. This demonstrates that physical effects other than formation of ion pairs and clusters must be incorporated into the Nernst-Planck model in order for it to correctly describe ion transport at higher salt concentrations. One prime candidate for such effects is the motion of the reaction surface resulting from dendrite growth.

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ionpairtheory - Accepted Manuscript
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More information

Accepted/In Press date: 1 June 2018
e-pub ahead of print date: 16 June 2018
Published date: 2018

Identifiers

Local EPrints ID: 421638
URI: http://eprints.soton.ac.uk/id/eprint/421638
ISSN: 0013-4651
PURE UUID: fcb151fa-7fbd-4786-a12d-916b843758a9

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Date deposited: 18 Jun 2018 16:30
Last modified: 26 Nov 2021 05:47

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Contributors

Author: Jamie M. Foster
Author: Athinthra Sethurajan
Author: Sergey Krachkovskiy
Author: Ion Halalay
Author: Gillian Goward
Author: Bartosz Protas

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