The Importance of Electrochemistry for the Development of Sustainable Mobility

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Friedl, Ulrich Stimming DPG-Frühjahrstagung, Working Group on Energy, 18.

1 TUM CREATE Centre for Electromobility, Singapore The Importance of Electrochemistry for the Development of Sustainable Mobility Jochen Friedl, Ulrich Stimming DPG-Frühjahrstagung, Working Group on Energy, TUM CREATE TUM Department of Physics E19 TUM Institute for Advanced Study

2 Bridging East and West 18 March

3 Outline Physical Background/ Operating Principle Outlook/ Perspectives State of the Art 18 March

4 Electrochemical Double Layer Capacitor 18 March

Electrochemical Double Layer Capacitor C pf 1 nf cm 2 + + + S.O.

2000 Electrode - - - - φ φ C DL = dq dφ 10μF cm 2 φ NHE 4. 5 V vs.

5 Electrochemical Double Layer Capacitor C pf 1 nf cm S.O. Kasap: Principles of Electrical Engineering Materials and Devices, McGraw-Hill Higher Education, 2000 Electrode φ φ C DL = dq dφ 10μF cm 2 φ NHE 4. 5 V vs. vacuum Q + Q - Electrolyte 0 x H x d Kolb DM. Angew Chem Int Ed Engl 2001;40: Klaus J. Vetter: Electrochemical Kinetics, Academic Press Inc., March x

C +/ = dq du C act = 1 C + + 1 C 1 C E = 1 2 C U2 P =

6 Electrochemical Double Layer Capacitor Béguin F et al. Adv Mater 2014:1 33. C +/ = dq du C act = 1 C C 1 C E = 1 2 C U2 P = 1 4 ESR U2 Energy stored in Electrochemical Double Layer (inner & diffuse) 18 March

7 Electrochemical Double Layer Capacitor Power Density U(t) = U 0 (1 exp t τ ) No charge transfer, no reaction: τ = C R s Small τ 10 kw kg -1 Simon P, Gogotsi Y. Nat Mater 2008;7: CAP-XX Supercapacitors for Micro-Hybrid Automotive Applications (2013). 18 March

μf cm -2 Pandolfo AG, Hollenkamp AF. J Power Sources 2006;157:11 27. Simon P, Gogotsi Y.

8 Electrochemical Double Layer Capacitor Energy Density E = 1 2 C(1 V)2 organic aqueous E = 1 2 C(U)2 C(2. 7 V)2 High Conductivity Electrochemical Stability High Surface Area Carbonaceous material: 5-20 μf cm -2 Pandolfo AG, Hollenkamp AF. J Power Sources 2006;157: Simon P, Gogotsi Y. Nat Mater 2008;7: CAP-XX Supercapacitors for Micro-Hybrid Automotive Applications (2013). 18 March

Electrochemical Double Layer Capacitor High conductivity Electrochemical stability High surface area Carbon TEM of typical Disordered Microporous (<2 nm) Carbon S BET ~ 2000 m 2 g -1 Above S BET ~

9 Electrochemical Double Layer Capacitor High conductivity Electrochemical stability High surface area Carbon TEM of typical Disordered Microporous (<2 nm) Carbon S BET ~ 2000 m 2 g -1 Above S BET ~ 1200 m 2 g -1 gravimetric C DL exhibits plateau. Barbieri Béguin 18 March F O et et 2014 al. al. Adv Carbon Mater 2005;43: :1 33. Béguin F et al. Adv Mater 2014: Simon P, Gogotsi Y. Nat Mater 2008;7:

10 Electrochemical Double Layer Capacitor Applications for Mobility: Simon P, Gogotsi Y. Nat Mater 2008;7: TOYOTA HYBRID: Hybrid at the Heart of Toyota Racing in 2014 (2014); CAP-XX Supercapacitors for Micro-Hybrid Automotive Applications (2013). 18 March

11 Batteries 18 March

Batteries Lead-Acid Battery U charged E = Q ΔU E 35 Wh kg 1 U/V vs. NHE PbO 2 /PbSO 4 1.69 Pb H + HSO 4 - PbO 2 U=2.

12 Batteries Lead-Acid Battery U charged E = Q ΔU E 35 Wh kg 1 U/V vs. NHE PbO 2 /PbSO Pb H + HSO 4 - PbO 2 U=2.04 V H + H 2 O Pb s + HSO 4 PbSO 4 s + H + + 2e Pb/PbSO Bard et al: Standard Potentials in Aqueous Solution, CRC Press, 1985 PbO 2 s + HSO 4 + 3H + + 2e PbSO 4 s + 2H 2 O Energy stored in Electrodes 18 March

Batteries Redox Flow Batteries E E = Q ΔU E eu 0 pos = -3.45 ev vs.

13 Batteries Redox Flow Batteries E E = Q ΔU E eu 0 pos = ev vs. vacuum VO 2+ E F,Me Energy stored in Electrolyte E F,Me D Me D El Negative Electrode V 3+ V 2+ eu 0 neg = ev vs. vacuum 18 March z D El Positive Electrode D Me

Batteries Redox Flow Batteries E E = Q ΔU E eu 0 pos = -3.45 ev vs. vacuum VO 2+ E F,Me E F,Me V 3+ V 2+ eu 0 neg = - 4.75 ev vs.

14 Batteries Redox Flow Batteries E E = Q ΔU E eu 0 pos = ev vs. vacuum VO 2+ E F,Me E F,Me V 3+ V 2+ eu 0 neg = ev vs. vacuum η = (U U 0 ) D Me D El Negative Electrode I = I 0 (exp 18 March D El D Me z α af Positive RT η exp α cf Electrode RT η )

7 Li X C 6 + + + + Li + Li 1-x CoO 2 U ~ 3.

15 Batteries Lithium-Ion Battery E 200 Wh kg 1 U charged E = Q ΔU U/V vs. Li/Li + Li 1-x CoO 2 / Li x CoO 2 ~3.7 Li X C Li + Li 1-x CoO 2 U ~ 3.6 V PF 6 - Li x C 6 C 6 + xli + + xe Li x C 6 /C 6 ~0.1 Li 1 x CoO 2 + xli + + xe Li x CoO 2 18 March

United States Advanced Battery Consortium Battery Pack: 200 km range in 15 min charging; 50 kwh energy content;

16 Batteries Battery: Electrical car designed as taxi for tropical megacities. 170 Wh kg -1 Pack: Lightweight CFRP body; Overhead air conditioning; 101 Seat Wh cooling; kg Wh kg -1 United States Advanced Battery Consortium Battery Pack: 200 km range in 15 min charging; 50 kwh energy content; 300 kg battery weight; 495 kg pack weight; 216 Li-Ion NMC cells; 400 V nominal voltage; 360 A max. current. 18 March Christian Huber, TUM CREATE

17 Batteries Energy Density E = Q ΔU silicon x Li + MX y Li x MX y Insertion Scrosati B, Garche J. J Power Sources 2010;195: x Li + MX y Li x X y + M Conversion/Alloying J.-M. Tarascon, M. Armand, Nature, 2001, 414, March

Batteries Alloying Anode: Silicon Full Discharge: Li 22 Si 5 4200 mah g -1 LiC 6 372 mah g -1 Problem: Extreme Volume change Capacity decay Possible Approach: Nanostructures with facile strain

18 Batteries Alloying Anode: Silicon Full Discharge: Li 22 Si mah g -1 LiC mah g -1 Problem: Extreme Volume change Capacity decay Possible Approach: Nanostructures with facile strain relaxation Nanostructured Si anodes are promising, but quantitative understanding is still missing and nature of SEI needs to be understood. 18 March Wu H, Cui Y. Nano Today 2012;7: McDowell et al. Adv Mater 2013;25:

19 current-collector separator Batteries Novel Cathode: Li-O 2 Discharge Mechanism: 2 Li + O 2 Li 2 O 2 Up to 1200 mah g -1 e - e - c c c Li 2 O 2 / Li 2 O c Challenges: Li Li + O 2 (air) Li x O 2 ( H 2 O, CO 2 ) Li 2 CO 3 LiOH c c [ LiO 2 ] solv. c + e - Li-electrode porous air-electrode Electrolyte stability; Blockage of porous carbon cathode with discharge products ( clogging ); Slow kinetics for charging. Y.-C. Lu,et al, Electrochem. & Solid-State Lett., 2010, 13, A69 18 March

20 Fuel Cells 18 March

fuel Fuel Cells Pt Pt oxidant j 0 Pt 1mA cm -2 j 0 Pt 2.

21 fuel Fuel Cells Pt Pt oxidant j 0 Pt 1mA cm -2 j 0 Pt ma cm -2 electrolyte Direct conversion of chemical into electrical energy; Constant supply of fuel and oxidant. Energy Conversion j 0 = R T nf R f A j = j 0 (Exp α anf RT η Exp α cnf RT η ) 18 March

Fuel Cells Complicated reaction mechanism Hydrogen related reactions: H 2 + 2 2 H ad H 2 + H ad + H + + e H ad + H + + e

22 Fuel Cells Complicated reaction mechanism Hydrogen related reactions: H H ad H 2 + H ad + H + + e H ad + H + + e Tafel Heyrovsky Volmer j 0 Pt 1mA cm -2 Slow kinetics Increase Temperature. Computational studies. Low power; High cost. Model catalyst studies. Values from: DOE Strategic Analysis: Mass Production Cost Estimation of Direct H 2 PEM Fuel Cell System for Transportation Applications (2012) Friedl J, Stimming U. Electrochim. Acta 2013;101: March

23 Fuel Cells Characteristic Curve PEM Many possible fuels high energy kinetic losses evident Friedl J, Stimming U. Electrochim. Acta 2013;101: March

24 POWER: No faradaic reactions ENERGY: Double layer only CYCLE LIFE: Very high, no faradaic reaction 18 March

25 POWER: Facile Charge transfer ENERGY: Stored in electrodes CYCLE LIFE: Low, electrode conversion 18 March

26 POWER: Sluggish Charge Transfer ENERGY: Stored in electrolyte CYCLE LIFE: High, electrodes for charge transfer 18 March

27 POWER: Intercalation reaction ENERGY: No conversion but intercalation CYCLE LIFE: High as strain small 18 March

28 POWER: ENERGY: Very sluggish O 2 reduction High energy density fuels 18 March

29 Thank you for your attention! 18 March

Electrochemistry and battery technology Contents

Electrochemistry and battery technology Contents Introduction Redox overview voltaic cells, electrolytic cells, fuel cells, Primary and secondary batteries. Other batteries; Construction, working and applications