Mass transport at electrified ionic liquid–electrode ... · COST 1206 – EXIL workshop, Prague,...
Transcript of Mass transport at electrified ionic liquid–electrode ... · COST 1206 – EXIL workshop, Prague,...
Vladislav Ivaništšev a, Luis M. Varela b, Ruth M. Lynden-Bell c and Maxim V. Fedorov d
a University of Tartu, [email protected] Universidade de Santiago de Compostela
c University of Cambridged Strathclyde University
Mass transport at electrified ionic liquid–electrode interfaces
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Table of contents
ApplicationsInterface
Chemical spaceComputer simulations
ResultsChallenges
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Current developments
Computer power, top500.orgEnergy sources, AVICCENNE
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The battery market and materials trends
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Ionic liquid–electrode interfaceEl
ectro
de
Surfa
ce ElectricalDouble
Layer (3 nm)Electrolyte
Mass&Charge transport
Computational screening:(1) 2185 Li intercalation and 18226 Li conversion electrodesbuild-a-battery.meteor.com(2) 11000 electrolytesM. Korth, PCCP 16 (2014).(3) Few studies of interfaces
Mass&Charge transport
Adsorption
Intercalation
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Chemical space of ionic liquidsM.V. Fedorov, A.A. Kornyshev, Chem. Rev. 114 (2014) 2978.
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Matrix of electrolyte compositions
[BMIm]+ [BMPyr]+ [BPy]+
[BF4]− c11 c12 c13
[DCA]− c21 c22 c23
[FSI]− c31 c32 c33
[TFSI]− c41 c42 c43
Li+ Na+ K+
F− h11 h12 h13
Cl− h21 h22 h23
Br− h31 h32 h33
I− h41 h42 h43
××
Variables:Electrode material
Surface chargeTemperature & Pressure
+
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NaRIBaS: A scripting framework for computational modelling of Nanomaterials & Room Temperature
Ionic Liquids in Bulk and Slab
NaRIBaS workflow:1. System preparation2. Equilibration
10 ns3. Production run
2 ns × n replica4. Data management5. Analysis
sourceforge.net/projects/naribas
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A naive view on the interface
3 nm 30 nm
Model interface Realistic interface
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Mass transport and Free energy profiles
Mass transport
A(z)
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Mass transport and Free energy profiles Probability method
Potential of mean force method ΔA
k=B exp(−Δ A /RT )
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Li+ ion approaching negative (left) and positive (right) graphene wallsσ = ∓1 e nm−2, cmol = 10%
dashed line – A(z)=−RTln(c/c0); solid line – from the pulling results
There is no contact minimum for Li+
adsorbing at negatively charged graphene from 10%
ionic liquid mixture
There is a very high barrier and a contact minimum
for Li+ adsorbing at negatively
charged graphene from 10% ionic liquid mixture
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Charged probe in [MMIm]Cl and [BMIm]BF4
+1
0
−1
Probecharge
+1
0
−1
Surfacecharge
×
anode − +
cathode + −
[A]− [C]+
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Solvation layers and the solvation shell
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Cylindrically averaged charge density
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Li+ and K+ at Graphite | BMImBF4 interface
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Li+ and K+ at Graphite | BMImBF4 interface
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Li+ and K+ at Graphite | BMImBF4 interface
metal-ion–anion bindinganion size
electrolyte densityJ.B. Haskins, et al., J. Phys. Chem. B 118 (2014) 11295.
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Conclusions The interfacial mass-transport of a probe ion (Li+, K+) is related to the
free energy profiles fom translation of the ion in direction perpendicular to the surface.
The structure of solvation layers at the electrodes determines the positions of the minima and maxima on the free energy profiles.
At those positions where these solvation structures enhance each other, the free energy profile is lower, whereas at those positions where they distort each other, the free energy is higher.
Barrier for K+ is lower than for Li+ in BMImBF4 + MeBF4 mixtures. The method presented can be applied for ionic liquids screening.
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Some preliminary results
Unpublished results
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Challenges
Potential scalePolarisable force fields
Constant potential simulations
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References V. Ivaništšev, M.V. Fedorov, R.M. Lynden-Bell, J. Phys. Chem. C 118 (2014) 5841. A.I. Frolov, K. Kirchner, T. Kirchner, M.V. Fedorov, Faraday Discuss. 154 (2012)
235. T. Méndez-Morales, J. Carrete, M. Pérez-Rodríguez, Ó. Cabeza, L.J. Gallego,
R.M. Lynden-Bell, L.M. Varela, Phys. Chem. Chem. Phys. 16 (2014) 13271.
See also● S.K. Reed, P.A. Madden, A. Papadopoulos, J. Chem. Phys. 128 (2008) 124701. ● V. Nikitina, S.A. Kislenko, R.R. Nazmutdinov, M.D. Bronshtein, G.A. Tsirlina, J.
Phys. Chem. C 118 (2014) 6151.● V. Ivaništšev, S. O’Connor, M.V. Fedorov, Electrochem. Commun. 48 (2014) 61.
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Acknowledgements
Maxim V. FedorovRuth M. Lynden-BellLuis Miguel Varela Cabo
Trinidad Méndez-MoralesIsabel Lage Lage-EstebanezKathleen & Tom Kirchner
Sean O'Conner
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Thank you for your attention!
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