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Présentation du 15 octobre 2009 Polymers vs. liquids, gels and ionic liquid electrolytes. Any winners? M. Armand, P.G.Bruce, B. Scrosati, W.Wieczorek Alistore.

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Presentation on theme: "Présentation du 15 octobre 2009 Polymers vs. liquids, gels and ionic liquid electrolytes. Any winners? M. Armand, P.G.Bruce, B. Scrosati, W.Wieczorek Alistore."— Presentation transcript:

1 Présentation du 15 octobre 2009 Polymers vs. liquids, gels and ionic liquid electrolytes. Any winners? M. Armand, P.G.Bruce, B. Scrosati, W.Wieczorek Alistore ERI |

2 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors) Composites (Ceramic, Anion receptors) Conclusions Conclusions

3 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors) Composites (Ceramic, Anion receptors) Conclusions Conclusions

4 Présentation du 15 octobre 2009 Strategies for Li Batteries Positives : Medium capacity “high” voltage Inorganic: LiFePO 4, Li 2 Fe(Mn)SiO 4 Very large capacity “low” voltage Organic: Li 2+x C 6 O 6 Electrolytes: New solutes, polymer (gels) ± ILs Negatives: Inorganic: Si Organic dicarboxylates Very high capacity Cu mandatory / binders? High capacity, 0.8 V Al option, s elec ??

5 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors) Composites (Ceramic, Anion receptors) Conclusions Conclusions

6 Présentation du 15 octobre 2009 Transport mechanisms Liquid electrolytes: transport of solvated species Polymer electrolytes: transport by solvation / desolvation Ceramic electrolytes: transport by ion hopping No net displacement of the host matrix

7 Présentation du 15 octobre 2009 Gels DN solvent > DN polymer DN polymer > DN solvent Direct polymer-cation interaction  no solvent drag Direct solvent-cation interaction  solvent drag The Donor Number of the polymer repeat units vs. that of the solvent DN PVF ≈ 0 < DN carbonates ≈ 15 < DN PEO ≈ 22

8 Présentation du 15 octobre 2009 Copyrights Marek Marcinek Li + PEO Polymer Electrolytes Polymer Electrolytes Electrodonor polymersElectrodonor polymers O,N,S (sufficient donor ability for complexation)O,N,S (sufficient donor ability for complexation) Sufficient distance between sitesSufficient distance between sites AmorphousAmorphous Polyethers good candidatesPolyethers good candidates Low Tg (flexibility)Low Tg (flexibility) General classification Polymer Comlexes Poymer Gels Polyelectrolytes (Single Ion Conductors)

9 Présentation du 15 octobre 2009 non volatility, no decomposition at the electrodes, no possibility of leaks, use of metallic lithium in secondary cells (lithium dendrites growing on the electrode surface would be stopped by the non-porous and solid electrolyte), lowering the cell price (PEO is cheaper than organic carbonates; it could be used as a binder for electrodes to improve the compatibility of consecutive layers; moreover fabrication of such a cell would be easier – cost), strengthening of cells thanks to the all-solid-state construction, shape flexibility, lowering the cell weight – non-volatile, all-solid-state cells don’t need heavy steel casing, improved shock resistance, better overheat and overcharge allowance, improved safety!!! Solid Polymer Electrolytes Advantages

10 Présentation du 15 octobre 2009 The most important and universal properties of polymeric electrolytes for application in lithium cells: chemical and mechanical stabilities over a wide temperature range, electrochemical stability of at least 3-4 V versus a Li electrode; especially important for battery applications low activation energies for conduction high cationic transport numbers good electrode ‑ electrolyte characteristics ease of sample preparation. Solid Polymer Electrolytes Advantages

11 Présentation du 15 octobre 2009 Polymeric electrolytes modifications Methods of modification of polymeric electrolytes: - random copolymers - block copolymers - comb-like copolymers - polymer blends - addition of liquid plasticizers - crosslinking (UV, gamma, chemical) - application of plasticizing salts - addition of anion receptors: –soluble Lewis acids –supramolecular receptors - polymer-in-salt materials –well-designed crystalline polymer electrolytes (NEW) –composites with inorganic fillers –ceramic-in-polymers –reversed phase systems (polymer-in-ceramic) (NEW)

12 Présentation du 15 octobre 2009 Generally an ideal electrolyte solvent should meet the following criteria: be able to dissolve lithium salts to sufficient concentration its viscosity should be low so fast ion transport can occur within electrolyte be inert to all cell components especially anode and cathode materials it should remain liquid in a wide temperature range (low melting and high boiling temperature are desirable) Electrolyte solvents

13 Présentation du 15 octobre 2009 The role of electrolyte is two, or sometimes threefold: It should provide ionic contact between electrodes allowing to close the circuit when the cell is operational It should assure electronic and spatial separation of the positive and negative electrode in order to avoid short-circuit and as a result – self discharge of the cell, which in some cases can be very spectacular (as those of failed high power Li-ion cells) In case of electrochemical systems where electrode components are not the only reactants appearing in the overall cell reaction, the electrolyte is the source (storage) of the remaining ones. Electrolyte solvents

14 Présentation du 15 octobre 2009 Alistore ERI | (a) Optimization of ion conductivity in mixed solvents: 1.0 M LiClO4 in PC/DME. (b) Dependence of dielectric constant (ε) and fluidity (η -1 ) on solvent composition. Chemical Reviews, 2004, Vol. 104, No. 10

15 Présentation du 15 octobre 2009 According to the functions targeted, the numerous chemicals tested as electrolyte additives can be tentatively divided into the following three distinct categories: (1) those used for improving the ion conduction properties in the bulk electrolytes; (2) those used for SEI chemistry modifications; and (3) those used for preventing overcharging of the cells… ….and thus improve SAFETY!!!! Electrolytes additives

16 Présentation du 15 octobre 2009 Donor Numbers + - D N for solvents: propensity to give electrons pairs (H of interaction to a reference Lewis acid) CH 2 Cl 2 MeNO 2 EC,PC, AN THF P(EO) DMFDMSOPy 03≈ 1522≈ The notion of D N for anions : D N (X - ) > D N (solvent) - + D N (X - ) < D N (solvent)  Role of  

17 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors) Composites (Ceramic, Anion receptors) Conclusions Conclusions

18 Présentation du 15 octobre 2009 Properties of the salt used for battery applications are as follows: it should be able to completely dissolve in the applied solvent at desired concentration and ions should be able to transfer through the solution anion should be stable towards oxidative decomposition at the cathode anion should be inert to electrolyte solvent both anion and cation should be inert towards other cell components anion should be nontoxic and remains thermally stable at the battery working conditions Anions – „A Letter to Santa”

19 Présentation du 15 octobre 2009 Anions-Role are an important part of SEI build-up at +/- electrodes Control transport numbers t + /t - Control dissociation and conductivity Control aluminium corrosion

20 Présentation du 15 octobre 2009 Classic Anions Tendency to decompose according to equilibrium: LiBF 4  BF 3 + LiPF 6  PF 5 + Fast reaction above 80°C  Destruction of electrolyte and interfaces AsF 6 - BF 4 - PF 6 - SbF 6 - ClO 4 - Explosive ! Toxic !

21 Présentation du 15 octobre 2009 Conceptual Approach to Anion Design “N, C” are favorable: Weak interactions Li—N but easy oxidation “O” is not a favorable building block: Strong Li—O interactions  ion pairing, ≠ ClO 4 -, BOB - If O present, F or C n F 2n+1 is required

22 Présentation du 15 octobre 2009 Diagonally Opposed Interests? + - Enhance the activity of anions (SN) Li + Organic chemistry Electrochemistry Maximize the conductivity Ionic processes I - = 2,2 Å  design of polyatomic anions

23 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors) Composites (Ceramic, Anion receptors) Conclusions Conclusions

24 Présentation du 15 octobre 2009 Hückel anions… X = N, C-CN, CR F, S(O)R F See P. Johansson et al Physical Chemistry Chemical Physics, volume 6, issue 5, (2004). Aromaticity 4n + 2 «  » electrons pK A = pK A = Gain of > 1 eV by resonance

25 Présentation du 15 octobre 2009 Cyanocarbons pK A < -3 corrodes glass Stronger than 100% sulfuric acid pK A < -10!!

26 Présentation du 15 octobre 2009 Hückel anions… DCTA Stable to 3.8 V (La Sapienza, KZ) inexpensive Gives quite fluid ILs

27 Présentation du 15 octobre 2009 LiTDI < LiPDI < LiDCTA < LiTFSI < LiPF 6 Gas Phase Ion Pair Dissociation Energies Ion pair (g) Li + (g) + Anion - (g) MP2/6-31G(d) LiTDI LiPDI LiDCTA LiTFSI LiPF 6 Scheers et al Excellent Theoretical Prediction

28 Présentation du 15 octobre 2009 Most Stable Lithium Imidazole Configurations LiTDI LiPDI B3LYP/6-311+G(d) Scheers et al Å 1.87 Å 1.92 Å 1.93 Å

29 Présentation du 15 octobre 2009 LiTDI (2-trifluoromethyl-4,5-dicyanoimidazole lithium salt) Easy, low ‑ demanding, inexpensive, one ‑ step, high yield syntheses; Salts are pure, stable in air atmosphere, non ‑ hygroscopic, stable up to 250°C, easy to handle; Important Benefits

30 Présentation du 15 octobre 2009 New salts - Synthetized Examples

31 Présentation du 15 octobre 2009 Exemplary Electrolyte Conductivities (20°C)

32 Présentation du 15 octobre 2009 New Salts - Anodic limit (Pt, EC- DMC) Real Chance to be >4V Class Battery

33 Présentation du 15 octobre 2009 Anodic limit (Al, EC-DMC) Real Chance to be >4V Class Battery

34 Présentation du 15 octobre 2009 Cycling LiMn 2 O V (EC-DMC) Swagelok cell, Al plunger Promising Cycling Performance…

35 Présentation du 15 octobre 2009 Ragone Signature..as well as Rate Capability and Power/Energy relation

36 Présentation du 15 octobre 2009 Conductivity in PEO SS / PEO 20 LiX / SS cooling scan LiDCTA LiPDI LiTDI

37 Présentation du 15 octobre 2009 PEO 20 LiCF 3 SO 3 + ZrO 2 SA Casting PEO 20 LiDCTA Hot-Pressing PEO 20 LiBOB/ LiBF 4 Hot-Pressing PEO 20 LiTDI PEO 20 LiPDI Hot-Pressing PEO 20 LiTDI PEO 20 LiPDI

38 Présentation du 15 octobre 2009 Charge profile 4.3 V cut-off, Al collector

39 Présentation du 15 octobre 2009 Li / PEO 20 LiX / Super P Anodic breakdown voltage vs. Li P(EO) 20 LiDCTA3.6V P(EO) 20 LiPDI4.0V P(EO) 20 LiTDI4.0V Anodic stability LiDCTA LiPDI LiTDI

40 Présentation du 15 octobre 2009 LiPDI LiTDI LiDCTA Li / PEO 20 LiX / Li Interphase resistance - PEO

41 Présentation du 15 octobre 2009 Cycling behaviour

42 Présentation du 15 octobre 2009 Rate capability (PEO) % of capacity at C/20

43 Présentation du 15 octobre 2009 New imidazole-derived salts Easy, low ‑ demanding, inexpensive, one ‑ step, high yield syntheses; Salts are pure, stable in air atmosphere, non ‑ hygroscopic, stable up to 250°C, easy to handle; 20°C ionic conductivity exceeds: 10 ‑ 3 S∙cm -1 in PC, 10 ‑ 4 S∙cm ‑ 1 in PEGDME ‑ 6 S∙cm ‑ 1 in PEO (10 ‑ 4 S∙cm ‑ 1 at 50°C) 6 mS∙cm ‑ 1 in EC:DMC T + at ionic conductivity maximum reaches: 0.45 in PC, 0.40 in EC-DMC, 0.25 in PEGDME500 (but overall max 0.62); Stable over time against Li; Stable up to 4.4 V vs. Li against metallic lithium anode; Stable up to 5.0 V vs. Li against aluminum; Much smaller association rate than commercially available salts;

44 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors) Composites (Ceramic, Anion receptors) Conclusions Conclusions

45 Présentation du 15 octobre 2009 Typical cations used in ionic liquids: 1) Imidazole cation 2) Alkylpyridine cation 3) Dialkylpyrrole cation Ionic liquid with lithium cation example Ionic Liquids (IL) 1/3

46 Présentation du 15 octobre 2009 The basic IL

47 Présentation du 15 octobre 2009 First Alkali metal IL? K(CF 3 SO 2 NSO 2 F) Eutectics, re-investigation of “polymer in salt” (Angell) 99°C

48 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors) Composites (Ceramic, Anion receptors) Conclusions Conclusions

49 Présentation du 15 octobre 2009 Fig.1 The structure of PEO 6 :LiAsF 6. Left, view of the structure showing rows of Li + ions perpendicular to the page. Right, view of the structure showing the relative position of the chains and their conformation (hydrogens not shown). Thin lines indicate coordination around the Li + cation. Fig.2 Conductivity of crystalline polymer electrolytes. Red - PEO 6 :LiAsF 6 ; green - PEO 6 :Li(AsF 6 ) 0.9 (SbF 6 ) 0.1 ; magenta - PEO 6 :(LiSbF 6 ) 0.99 (Li 2 SiF 6 ) 0.01 ; blue - PEO 6 :(LiAsF 6 ) 0.95 (LiTFSI) 0.05 ; black - (PEO 0.75 G ) 6 :LiPF 6. G4 – tetraglyme, CH 3 O(CH 2 CH 2 O) 4 CH 3. Crystalline Solid Polymer Electrolytes 1/2

50 Présentation du 15 octobre 2009 Fig.3 The structure of PEO 8 :NaAsF 6. Left, view of the structure showing rows of Na + ions perpendicular to the page. Right, view of the structure showing the relative position of the chains and their conformation (hydrogens not shown). Thin lines indicate coordination around the Na + cations. Crystalline Solid Polymer Electrolytes 2/2

51 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors, Ceramic „sponges”) Composites (Ceramic, Anion receptors, Ceramic „sponges”) Conclusions Conclusions

52 Présentation du 15 octobre 2009 Lithium transference numbers for (PEO) 20 LiClO 4 based composite electrolytes containing 10% by weight of inorganic filler additives Type of the electrolyte Type of the fillerTemperature/ o CLithium transference number (PEO) 20 LiClO 4 Filler free sample (PEO) 20 LiClO 4 Al 2 O (PEO) 20 LiClO 4 Al 2 O 3 (1% ASG) (PEO) 20 LiClO 4 Al 2 O 3 (4% ASG) (PEO) 20 LiClO 4 Al 2 O 3 (8% ASG) (PEO) 20 LiBF (PEO) 20 LiBF 4 Surface modified ZrO PEO-based electrolytes transference number

53 Présentation du 15 octobre 2009 Alistore ERI | Type of the electrolyte Molar fraction of calix- 6-pyrrole Temperature/ o C Lithium transference number (PEO) 20 LiI (PEO) 20 LiI (PEO) 20 LiAsF (PEO) 20 LiAsF (PEO) 20 LiBF (PEO) 20 LiBF (PEO) 20 LiBF (PEO) 20 LiBF (PEO) 100 LiBF (PEO) 100 LiBF (PEO) 20 LiCF 3 SO (PEO) 20 LiCF 3 SO Lithium transference numbers for PEO-LiX-Calix-6-pyrrole electrolytes

54 Présentation du 15 octobre 2009 How does it (probably) work? OOO O O ClO 4 - Li + ClO 4 - Li + Calix O 1)K I >K cal >K T 2)K I >K T >K cal 3) K cal >K I >K T K I -ion pairs formation constant K T -ionic tiplets formation K cal -calix-anion complex constant

55 Présentation du 15 octobre 2009 Cyclic voltammograms of LiTf:PEO20 membranes with and without C6P and SiO2 additives at (a)75˚C and (b)90˚C over potential range of 0-5.0V using SS/PE/SS cell configuration H. Mazor, D. Golodnitsky, E. Peled, W. Wieczorek, B. Scrosati, J.Power Sources, 178 (2008) PEO-based electrolytes additives stability

56 Présentation du 15 octobre 2009 Inhibition of crystallization New Types of Ceramic Composites 1/2 – Concept and Structure

57 Présentation du 15 octobre 2009 New Types of Ceramic Composites 2/2 – Preliminary/First!!! Electrochemical Testing

58 Présentation du 15 octobre 2009 Alistore ERI | Outline General status quo of present Li (ion) battery architecture Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Introduction to the field of modern electrolytes (concepts, transport mechanisms, improvement strategy) Role of salt anions Role of salt anions New types of salts New types of salts Ionic Liquids Ionic Liquids Crystalline Electrolytes (P. Bruce) Crystalline Electrolytes (P. Bruce) Composites (Ceramic, Anion receptors) Composites (Ceramic, Anion receptors) Conclusions Conclusions

59 Présentation du 15 octobre 2009 Conclusions Anion design is one (most?) of the important aspect of electrolyte improvement Hückel anions offer a cheap alternative and are covalent (i.e. easy to handle, dry…)! CF 3 (C 2 F 5 ) dicyano imidazoles are 4.6 V and do not corrode aluminum Many tools but still a lot of steps towardMany tools but still a lot of steps toward better real life systems better real life systems Role of positive input/collaboration from the industry!

60 Présentation du 15 octobre 2009 Acknowledgements The following scientists greatly contributed to the preparation of this report: From Warsaw University of Technology: Marek Marcinek Leszek Niedzicki Jarosław Syzdek From University of St. Andrews: Yuri Andreev From Chalmers University: Per Jacobsson Patrik Johansson Johan Scheers


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