Mass transport at electrified ionic liquid electrode interfaces

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1 Mass transport at electrified ionic liquid electrode interfaces Vladislav Ivaništšev a, Luis M. Varela b, Ruth M. Lynden-Bell c and Maxim V. Fedorov d University of Tartu, vi@ut.ee b Universidade de Santiago de Compostela c University of Cambridge d Strathclyde University a

2 Table of contents Applications Interface Chemical space Computer simulations Results Challenges 2

3 Current developments Energy sources, AVICCENNE Computer power, top500.org 3

4 The battery market and materials trends 4

18226 Li conversion electrodes build-a-battery.meteor.com (2) 11000 electrolytes M.

5 Ionic liquid electrode interface Mass&Charge transport Mass&Charge transport Adsorption Surface Electrode Intercalation Computational screening: (1) 2185 Li intercalation and Li conversion electrodes build-a-battery.meteor.com (2) electrolytes M. Korth, PCCP 16 (2014). (3) Few studies of interfaces Electrical Double Electrolyte Layer (3 nm) 5

6 Chemical space of ionic liquids M.V. Fedorov, A.A. Kornyshev, Chem. Rev. 114 (2014)

7 Matrix of electrolyte compositions [BMIm]+ [BMPyr]+ [BPy]+ [BF4 ] c11 c12 c13 [DCA] c21 c22 c23 [FSI] c31 c32 c33 [TFSI] c41 c42 c43 F Li+ h11 Na+ h12 K+ h13 Cl h21 h22 h23 Br h31 h32 h33 I h41 h42 h43 + Variables: Electrode material Surface charge Temperature & Pressure 7

NaRIBaS: A scripting framework for computational modelling of Nanomaterials & Room Temperature Ionic Liquids in Bulk and Slab NaRIBaS workflow:

8 NaRIBaS: A scripting framework for computational modelling of Nanomaterials & Room Temperature Ionic Liquids in Bulk and Slab NaRIBaS workflow: 1. System preparation 2. Equilibration 10 ns 3. Production run 2 ns n replica 4. Data management 5. Analysis sourceforge.net/projects/naribas 8

9 A naive view on the interface 3 nm 30 nm Model interface Realistic interface 9

10 Mass transport and Free energy profiles Mass transport A(z) 10

11 Probability method Potential of mean force method ΔA Mass transport and Free energy profiles k= B exp( Δ A / RT ) 11

Li+ ion approaching negative (left) and positive (right) graphene walls σ = 1 e nm 2, cmol = 10% dashed line A(z)= RTln(c/c0); solid line from the pulling results There is a very high barrier and a

12 Li+ ion approaching negative (left) and positive (right) graphene walls σ = 1 e nm 2, cmol = 10% dashed line A(z)= RTln(c/c0); solid line from the pulling results There is a very high barrier and a contact minimum for Li+ adsorbing at negatively charged graphene from 10% ionic liquid mixture There is no contact minimum for Li+ adsorbing at negatively charged graphene from 10% ionic liquid mixture 12

13 Charged probe in [MMIm]Cl and [BMIm]BF4 Probe charge Surface charge [A] [C]+ anode + cathode + 13

14 Solvation layers and the solvation shell 14

15 Cylindrically averaged charge density 15

16 Li+ and K+ at Graphite BMImBF4 interface 16

17 Li+ and K+ at Graphite BMImBF4 interface 17

18 Li+ and K+ at Graphite BMImBF4 interface metal-ion anion binding anion size electrolyte density J.B. Haskins, et al., J. Phys. Chem. B 118 (2014)

19 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. 19

20 Some preliminary results Unpublished results 20

21 Challenges Potential scale Polarisable force fields Constant potential simulations 21

22 References V. Ivaništšev, M.V. Fedorov, R.M. Lynden-Bell, J. Phys. Chem. C 118 (2014) 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) See also S.K. Reed, P.A. Madden, A. Papadopoulos, J. Chem. Phys. 128 (2008) V. Nikitina, S.A. Kislenko, R.R. Nazmutdinov, M.D. Bronshtein, G.A. Tsirlina, J. Phys. Chem. C 118 (2014) V. Ivaništšev, S. O Connor, M.V. Fedorov, Electrochem. Commun. 48 (2014)

23 Acknowledgements Ruth M. Lynden-Bell Luis Miguel Varela Cabo Maxim V. Fedorov Trinidad Méndez-Morales Isabel Lage Lage-Estebanez Kathleen & Tom Kirchner Sean O'Conner 23

24 Thank you for your attention! 24

25 zotero.org/groups/ionic_liquids Comprehensive collection of articles on ionic liquids in bulk and at interfaces Based on the Prof. M.V. Fedorov's group bibtex-collection Zotero Group Library (1174 items+pds) Address: zotero.org/groups/ionic_liquids Public type, but closed membership Zotero free and open-source reference management software to manage bibliography Web browser integration, syncing, generation of citations , Santiago de Compostela 25

26 Zotero Zotero 0$/120$ Mendeley 0$/50x$ , Santiago de Compostela EndNote 150$/150x$ 26

27 World cloud , Santiago de Compostela 27

28 Topic modeling by 3 words ( ) , Santiago de Compostela 28

29 Research center ranking by number of publications , Santiago de Compostela 29

Poly(a)morphic portrait of the electrical double layer in ionic liquids

Poly(a)morphic portrait of the electrical double layer in ionic liquids V. Ivaništšev a,, S. O Connor a, M.V. Fedorov a, a Department of Physics, Scottish Universities Physics Alliance (SUPA), Strathclyde