On the Dynamic Frontier of R&D of novel power sources

Transcription

1 On the Dynamic Frontier of R&D of novel power sources In collaboration with BASF,GM,Pellion Doron Aurbach Bar Ilan university, Israel Dr. Ran Elazari Ariel Rosenman Prof. Gregory Salitra Daniel Sharon Prof. Boris Mrkovsky Prof. Elena Markevich And many others..

2 Full EV can drive only 160 km between charges. Nevertheless, it is now a business!!! Li ion batteries take the lead! Main xev`s Makers BEV Audi BMW BYD GM Chrysler Daimler/Merc edes Fiat Ford Honda Hyundai Kia Mazda Mitsubishi Nissan Porsche Proterra Saab Tesla Toyota Volvo Volkswagen Wheego HEV Acura/Honda Audi Azure BMW GM Daimler/Mercede s Eaton Fiat Ford Honda Hyundai Jaguar Kia Land Rover Mitsubishi Nissan Porsche Subaru Toyota Volvo Volkswagen PHEV Audi BMW GM BYD Dodge Fisker Ford Honda Hyundai Jaguar Land Rover Lotus Daimler/Merced es Mindset Mitsubishi Porsche Suzuki Toyota VIA Motors Volvo Volkswagen

3 Most Rechargeable Li + ion Batteries in Use Today Click to edit Master title style Cathodes Li X CoO 2 LiFeO 4 Li[MnNiCO 2 Cathode Surface films Anode Surface films Anode Li X C 6 Electrolyte solution: Ethylene-Carbonate & Di-Methyl Carbonate/ LiPF 6 Voltage: 3.7 V, Average Energy Density: 150 Wh/Kg D. Aurbach et Al., Materials Today, 2014

4 Advanced Li ion batteries : the challenge of new anodes Si anodes (Li 4.2 Si > 3500 mah/g), but need unique morphology Click to edit Master title style A Monolithic electrodes comprising Si nano-wires B EC-DMC/LiPF 6 Pristine Monolithic Si electrodes 1 µm by sputtering 10 µm 10 µm C Cycled in: DMC-FEC/LiPF 6 EC-DMC-FEC/LiPF 6 D 1 µm 1 µm 10 µm 10 µm Surface films formed in FEC-containing solutions were much thinner and compact D.Aurbach et Al., Langmuir, 28, 6175 (2012)

5 Capacity [mah/g] Capacity [mah/g] Galvanostatic cycling of monolithic Si electrodes Click in DMC:FEC to edit 4:1 1M Master LiPF 6 ( magic ) title style solution at 30 o C Current ma (C/5 rate) Cycle no. Electrodes based on Si NW Charge Discharge Current ma (C/2.5 rate) Cycle no. Electrodes based on Si sputtered on Cu Charge Discharge

6 High voltage cathodes: LiNi 0.5 Mn 1.5 O 4 /Si cells (Monolithic Si electrodes prepared by sputtering) C/8 FEC-based electrolyte C/2 FEC-based electrolyte C/2 Markevich, Salitra & Aurbach, Electrochem. Comm.,

7 Voltage, V Click to edit Master title style Olivine Cathodes, the limiting factor The LiMPO 4 olivine Family Voltage Range (V) theoretical Energy Density (mah/ g) LiFePO (165 practical) LiMnPO (150 practical) LiMn 0.8 Fe 0.2 PO (160 practical) LiCoPO ( practical) 6 5 LiCoPO 4 4 LiMnPO 4 LiMn 0.8 Fe 0.2 PO LiFePO 4 For LiFePO 4, LiMnPO 4, LiMn 0.8 Fe 0.2 PO 4 : Low cost, reasonable capacity Good safety:low toxicity, high thermal stability High rate capability For LiCoPO 4 High voltage, lower capacity, stability??? Capacity, mah/g

8 It appears that XRD is less sensitive than HRTEM in studies of the phase transitions and cation ordering in the integrated layered material. Li & Mn rich Li 1+x [Mn y Ni z Co w ]O 2 Click to edit Master title style R3M rhombohedral LiMO 2 : M=transition metal ion) high capacity cathodes C2/m monoclinic phase: Li 2 MnO 3 = Li[Li 1/3 Mn 2/3 ]O 2 Molecularly integrated material M Unique morphology of the BASF cathode materials

9 HC-MNC activated at 4.8 V in 1st cycle, further Click cycled to up edit to cut-off Master potential title 4.6 style V

10 Voltage / V Voltage / V Typical voltage profiles at various currents applied C-rate of the xli 2 MnO 3. (1-x)Li[MnNiCo]O 2 electrodes Click to edit Master title style Uncoated Cycle AlF 3 -Coated 1-st Cycle ICL = 23.2 % ICL = 5.1 % C C C/7 C/14 C/20 Discharge capacity / mahg C C/7 C/14 C/ Discharge capacity / mahg -1 The Irreversible capacity loss of the AlF 3 coated electrode is less due to lesser oxidation reactions at high anodic potentials Significant increase of the discharge capacity of the AlF 3 coated electrodes is due to higher Li storage capability of these electrodes. 2C Aurbach, Garsuch, Lampert, Schulz-Dobrick et Al., J. Electrochem. Soc., 160, A2220 (2013)

11 Advantages of Li-S and Li-O 2 over Li-ion systems Higher Theoretical capacity, energy and power density. Low cost (1$ per 100g) and abundant raw materials (350 ppm). Operability at low temperature (-40 C). Bruce, P. G., Freunberger, S. A., Hardwick, L. J., Tarascon, J.-M.. Nature materials 11, (2012). 11

12 Working Mechanism Formation and re-oxidizing Li 2 S n Sulfur-cathode LiNO 3 Li-anode + + Discharge S 8 Li 2 S 8 Li 2 S 6 Li 2 S 4 Li 2 S 2 Li 2 S Li-Polysulfudes diffuse to the anode Insoluble products Shuttle effect 12 Charge Bar Ilan University 12 12

13 Rechargeable lithiated silicon-sulfur (SLS) cells vs. Li-S reference cells, an important new direction Li Sulfur Cells (reference) Sulfur/Lithiated a-si Li-Ion Cells 13

14 Activated carbon cloth impregnated with sulfur as possible cathodes for Li-S system. Electrode Preparation S 8 a b c 14

15 Electrochemical performance of S/kynol 2000 Discharge potential is limited to 1.9V Charge/Discharge capacity vs. cycle number 0.65 ma/cm2 Charge/Discharge profiles vs. voltage 1.3 ma/cm2 ~3.12 mg/cm 2 of sulfur impregnated on activated carbon cloth disc (kynol 2000 m 2 /g, 14 mm φ) under vacuum in a sealed glass ampulla at 200 C for 10h. Cell where cycled at current density of ~1 ma/cm 2 (~C/5) unless indicated otherwise between the voltage range of 2.5V and 1.9V. Binder Free. Rigid Structure. High Porosity & Surface Area. 15

16 Li-L 2 S cells: towards Li ion sulfur systems a) b) Proposed mechanism for redox mediated Li 2 S oxidation Ox. Li 2 S Li 2 S Li 2 S Red. Pristine Electrode No Additive With Redox Couple The best red-ox mediator we found so far: Decamethylferrocene Fe(η 5 -C 5 Me 5 ) 2

17 Using monolithic high surface area activated carbon cloth electrodes Decoration by α-mno 2 nano-particles can reduce the oxidation potential via electro-catalysis The most relevant electrolyte solution: CH 3 O(CH 2 CH 2 O) n CH 3 / LiTFSI LiN(SO 2 CF 3 ) V ACM ACM α-mno 2 The over-potential dropped to in more then 0.5 V by introducing MnO 2 catalyst D. Aurbach et Al.,J. Mater. Chem. A, 1, 5021(2013)

18 Proposed degradation mechanism of polyether solvents during oxygen reduction (in the presence of Li ions) Li O O Li b a a H 3 CCO 2 Li CH 3 OCH 2 CH 2 OCH 2 CH 3 O Li :B 6b 1 H HB Li 2 O 2 b d O CH 3 CHO d 5 6a CH 3 OO Li + OCH 2 CH 2 OCH 2 c 2 3 c Li OCH 2 CH 2 O Li Li O O Li 4 H 2 C O Li 2O 2 HCO 2 Li 7 Li 2 O 2 LiOCO 2 Li CO 2 + LiOLi 10 The lithium cation is a hard electrophile which is expected to bond strongly to the hard Lewis base oxygen anions. This in turn helps to convert the alkoxy groups into better leaving groups and facilitates nucleophilic attacks by Li 2 O 2.

19 Are rechargeable Li-O 2 batteries realistic? Electrolyte solution stability ORR- reactivity with the oxides OER- low solution oxidation potential 1. Carbonates 2. Polyether? 3. DMSO 4. DMF??? Carbon stability Enhances electrolyte solution degradation Carbon replacement? Reacts with O 2, super-oxides & peroxides Catalyst integration Enhances solution degradation and oxidation Introducing more contaminations

20 5 nm Still not found The perfect system O 2 O 2 O 2 GAS

21 Carbonates solvents Non functional system O 2 O 2 GAS

22 500 nm Polyethers, DMSO, Sulfolane, DMF, Etc... Complex system + O 2 O 2 GAS

23 5 nm More studies should be done Complex system with inert Negligible cathode + O 2 Inert cathode O 2 GAS

24 The effect of the lithium oxides source Chemical reactions of oxides may be very different from those observed under electrochemical reactions that involve primarily electron transfer processes. In fact, the main side reactions should occur during the formation of the reduced oxygen species in the anionic form (catalyzed by Li ions in solutions, before precipitation as solid Li 2 O 2 deposits. Substrates: organic Moieties / Solvent molecules

25 LiMn 2 O 4, LiFePO 4 or LiMn 0.8 Fe 0.2 PO 4 cathodes (2.5-2 V highly stable batteries) Conclusions and open questions There are no stable polar-aprotic solvents suitable for ORR in the presence of Li ions. The high reactivity relates to oxides and Li ions in solution phase. Solid Li 2 O 2 is not too reactive. Li ions are hard electrophiles. Moving to other cations (Na + ) may change the game. Carbon electrodes are also problematic. They react with O 2, oxides and degrade. At this stage, we have serious problems in the course of ORR. Too early to discuss catalysis. Finally, when we will solve all the above problems, we will face the real ones.a lot of hard work needed! Do not promise anything. Li ion battery technology is reaching its limits. Load leveling becomes more & more important: Super Capacitors, Na ion batteries, Mg batteries, flow batteries, Li ion batteries with LTO (Li 4 Ti 5 O 12, 1.5V) anodes vs.

26 Super- capacitors (high power, prolonged cycling) s Just capacitive, electrostatic interactions Anions Adsorption desorption Li ions Intercalation De-intercalation

27 Low voltage, long life Li ion batteries, based on LTO anodes. A contribution of Li ion technology for load leveling applications? 3.3V 2.5V 2V

28 Warning During the last several decades, the battery community demonstrated highly important progress. The development and commercialization of Li ion batteries is the most impressive success of modern electrochemistry. Our modern life which are characterized by an intensive use of mobile electronic equipment: cellular phones, laptops, cameras and more are affected so much by the high fidelity and reliability of Li ion battery technology. Now we are challenged by the demands for electrochemical propulsion. We are expected to provide fast revolutions (see for instance the program ) The risk is very serious. It took us so many years of excellent scientific hard work to reach our prestige. We should not loose it!!! We should not promise thinks that we may not be able to deliver. It is much better to be a-priori moderate and then surprise