Werkstoffforschung in der Batterietechnik

Transcription

1 Werkstoffforschung in der Batterietechnik Philipp Adelhelm Institute for Technical Chemistry and Environmental Chemistry Center for Energy and Environmental Chemistry (CEEC Jena) Friedrich Schiller University Jena, Germany Thüringer Werkstofftag 2017, , Jena

2 Different technologies for rechargeable batteries Energy by volume (Wh/L) Future high energy chemistry? smaller Li ion technology 300 NiMH Future low cost chemistry? 200 NiCd 100 Pb acid lighter Energy by weight (Wh/kg)

3 Lithium ion batteries The limits? Graph: data redrawn from Fraunhofer ISI report Dec Are we reaching the limits? How important is safety?

4 Lithium ion batteries: Materials Graphite (LiC 6 ) LiCoO 2 Li[Ni 1 x y Mn x Co y ]O 2 Li[Ni 0.8 Co 0.15 Al 0.05 ]O 2 LiFePO 4 LiMn 2 O 4 anode cathode Remember: The Li ion battery does not exist! Many variations are on the market. The main difference between the various types is due to the different materials that are used for the positive and negative electrode. Which material combination is used, depends on the application.

5 Materials for lithium ion batteries A typical EV battery 60 kwh (435 kg) ca. 350 km An estimate*: Li Co Mn Ni 6.5 kg 18 kg 17 kg 18 kg Graphite 45 kg Cu 60 kg Al 37 kg * Estimate includes active materials and current collectors only. Values calculated assuming Graphite/NMC cells

6 Materials for lithium ion batteries Supply From: Bottleneck materials for the deployment of low carbon technologies in the EU. Dr. V. Tzimas, JRC, 23 Feb 2017

7 Approaching the limits: Energy density W = QU E C E A + +

8 Higher capacity: More lithium ions per electrode mass and volume Lithium Graphite (LiC 6 ) Other carbons (Li 1+x C 6 ) Si (Li 4.4 Si) Sn (Li 22 Sn 5 ) anode Task for materials scientists: cathode Replace graphite by metal alloys or use even pure lithium! Alloys: Up to 10x higher capacity than graphite but poor cycle life Lithium: Highest capacity but unsolved safety issues for decades

9 Higher capacity: More lithium ions per electrode mass and volume Lithium Graphite (LiC6) Other carbons (Li1+xC6) Si (Li4.4Si) Sn (Li22Sn5) discharge + Li Li e charge anode cathode Higher capacity: Replace graphite by metal alloys or use even pure lithium! Alloys: Up to 10x higher capacity than graphite but poor cycle life Lithium: Highest capacity but unsolved safety issued for decades

10 Higher capacity: More lithium ions per electrode mass and volume LiCoO 2 Li[Ni 1 x y Mn x Co y ]O 2 Li[Ni 0.8 Co 0.15 Al 0.05 ]O 2 LiMn 2 O 4 LiNi 0.5 Mn 1.5 O 4 Overlithiated NMC anode Task for materials scientists: cathode Increase content of nickel, eventually overlithiate materials! Nickel: Higher capacity + higher voltage but lower cycle life Overlithiate: Much higher capacity but voltage fade

11 Higher capacity: More lithium ions per electrode mass and volume Li[Ni 1-y-z Co y Mn z ]O 2 ( NMC or sometimes NCM, or MNC, depending on what people prefer) 0.0 Co (LCO) 1.0 Rule of thumb: More Ni: Higher capacity More Mn: Lower price, better thermal stability More Co: Better cycle life Classic high stability region High capacity low safety region 0.2 Lower cost region Ni Mn (LMO) Composition Diagram State of the art compositions in application are NCM 111, NCM 523, NCM 424. But NCM 811 is aimed for! Ni (LNO)

12 Improving Li ion technology anode cathode Better electrolytes!

13 Improving Li ion technology: Better electrolytes Source: Diagram data from R. Stringfellow et al. TIAX, 2010; presented by J. Garche, AABC Europe, 2016 In case of fire, roughly 2/3 of the heat release is due to combustion of the organic electrolyte! Also quite some HF is released ( g HF per kwh).

14 Improving Li ion technology: Better electrolytes anode cathode Polymer electrolytes: Studied for more than 35 years but no commercialization yet. Solid electrolytes: Quite recent topic, high risk high gain. Toyota is frontrunner.

15 Lithium ion is not enough: Next generation systems P. Adelhelm et al., Beilstein J. Nanotech, 2015

16 Li/O 2 batteries maximizing energy density Cell reaction: Discharge 2 Li O ( g) Li O 2 Charge 2 2 E = 2.96 V w th = 3460 Wh/kg(MO) Concept introduced 1996 by K.M. Abraham, J. Electrochem Soc., 1996, 143, 1 5

17 Li/S batteries maximizing energy density Image Source: Ken Cooper Photography Cell reaction: Discharge 2 Li 1/8 S 8 2 Li2S Charge E = 2.24 V, w th = 2615 Wh/kg 2Li + 1/8 S 8 Li 2 S 8 Li 2 S 6 Li 2 S 4 Li 2 S 2 Li 2 S non conducting solid soluble non conducting solid

18 Li/S batteries maximizing energy density Image Source: Ken Cooper Photography Cell reaction: Discharge 2 Li 1/8 S 8 2 Li2S Charge E = 2.24 V, w th = 2615 Wh/kg 2Li + 1/8 S 8 Li 2 S 8 Li 2 S 6 Li 2 S 4 Li 2 S 2 Li 2 S non conducting solid soluble non conducting solid

19 Improving Li ion technology: What else? anode cathode

20 Improving Li ion technology: What else? anode cathode Replace Li + by Na +, K +, Al 3+, Mg 2+,

21 Reserves as an advantage for sodium C. Wadia et al., Journal of Power Sources, 196, 2011

22 LIB vs. NIBs LCO and NCO as example LCO: NCO: P. Adelhelm, Nachrichten aus der Chemie, 12/2014 LCO and NCO do not compare at all! mainly solid solution behavior very complex phase behavior related to ordering of Na + vacancies and [CoO 2 ] layers

23 Li/O 2 vs. Na/O 2 : Voltage profile Lithium/oxygen cell: Sodium/oxygen cell: Li 2 O 2 NaO 2 j = 20 µa cm 2 j = 200 µa cm 2 High overpotentials Low discharge capacities Low overpotentials High discharge capacities P. Hartmann et al., Nature Materials, 12, 2013 C. L. Bender et al., Adv. Energy Mater., 4, 2014 C. L. Bender et al., Angewandte Chemie Int. Ed., 55, 2016

24 Conclusion Lithium ion battery technlogoy is constantly improved and will dominate the rapidly growing market. Energy density increases at a rate of 5 10 % per year, but we will likely reach the limits soon (energy density vs. safety). What will be the role of Europe and Germany? A range of alternative materials is studied intensively worldwide mostly with the aims of increasing capacity and/or cell voltage. This is challenging and often incremental work characterized by fine tuning the composition and amounts of all battery components. Disruptive technologies can, but might not, change the game: Lithium air, lithium sulfur, solid state batteries, Sodium, Magnesium,.

25 Acknowledgment Jena team: Dr. Prasant Nayak Wolfgang Brehm Mustafa Göktas Lukas Medenbach Santosha Lingamurthy Liangtao Yang Dr. Thangavelu Palaniselvam Master students: Jonas Geisler, Ines Escher, Thomas Blesch, Shan Liu, Marie Ann Schmid and Prof. Jürgen Janek, Dr. Pascal Hartmann, Dr. Ricardo Pinedo, Dr. Amrtha Bhide, Dr. Conrad Bender, Dr. Sebastian Wenzel, Dr. Birte Jache, Dr. Franziska Klein, Christine Eufinger, Martin Busche Battery and Electrochemistry Network