David N Fronczek 123 and Wolfgang G Bessler 124 1 German Aerospace Center DLR 2 Helmholtz Institute Ulm HIU 3 Lawrence Berkeley National Laboratory LBNL 4 From 092012 Offenburg University of Applied Sciences ID: 935312
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Slide1
A virtual Li/S battery: Modeling, simulation and computer-aided development
David N. Fronczek
1,2,3
and Wolfgang G. Bessler
1,2,4
1
German Aerospace Center (
DLR
)
2
Helmholtz Institute Ulm (
HIU
)
3
Lawrence Berkeley National Laboratory (
LBNL
)
4
From 09/2012: Offenburg University of Applied Sciences
Slide2> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
A virtual Li/S battery: Modeling, simulation and computer-aided development
Introduction
Fundamentals of Li/S batteries
Modeling approachSimulation resultsOutlook & Summary
www.DLR.de
•
Chart
2
Slide3DLR
– The German Aerospace
Center
Locations and employees
~8000 employees across
33 institutes and facilities at
13 sites.
Offices in Brussels,
Paris and Washington.DLR Institute of Technical Thermodynamics: R&D activity of Electrochemical Energy Technology since 1986
n
Cologne
n Oberpfaffenhofen
Braunschweig n
n Göttingen
Berlin n
n Bonn
n Neustrelitz
Weilheim n
Bremen n
n Trauen
n Dortmund
Lampoldshausen n
Hamburg n
Stuttgart n
> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
www.DLR.de
• Chart 3
http://www.dlr.de/tt/en/
Slide4Electrochemical Energy Technology
Head: Prof. K. Andreas Friedrich
Personnel
About 60 employees
5 research areasSOFC – Günter Schiller
PEFC
–
Erich
Gülzow Batteries – Norbert WagnerModeling – Wolfgang Bessler
Electrochemical systems – Josef
KalloBudget 2011~ 8 M€ (without operation cost of large test facilities)About 50 % third-party funding
> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
www.DLR.de
• Chart 4
Slide5Modeling and simulation of lithium batteries
LiFePO
4
batteries:
Electrochemistry and impedance
Understanding and optimization of physicochemical behavior
Thermal management and runaway risk
Understanding and optimization of thermal and safety behavior
Lithium-sulfur cells:
Redox chemistry and transport
Analysis of cycling properties
and chemical reversibility
Lithium-air cells:
Multi-phase chemistry and reversibility
Improvement of porous air electrode
Lithium-ion technology
Post lithium-ion cells
> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
www.DLR.de • Chart 5
Slide6Helmholtz Institute Ulm forElectrochemical Energy Storage
Center of Excellence for research in electrochemical energy storage
Started in Jan. 2011
New building on University Ulm campus
for 80 scientists (2013)DLR battery modeling activities are integrated into HIU
> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
www.DLR.de
•
Chart
6
http://www.hiu.kit.edu/
Slide7> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
A virtual Li/S battery: Modeling, simulation and computer-aided development
Introduction
Fundamentals of Li/S batteries
Modeling approachSimulation resultsOutlook & Summary
www.DLR.de
•
Chart
7
Slide8www.DLR.de •
Chart
8
> Lithium/Sulfur Batteries: An Elementary Modeling Approach > D. N. Fronczek • ModVal 9 > April 2, 2012
Lithium/sulfur batteries – properties and potentials
Li-Ion
high
E
Pb
Li-Ion
high PLi/S
Li-air
gasoline
(50 % of theoretical max.)
10
100
1 000
10 000
Specific Energy / Wh/kg
Y. Mikhaylik et al., Sion Power Corp., ECS presentation, 2009.USABC targetsLi/S (2009)
Rate Cap.
Lower TPower Density
Specific PowerRecharge Time
Specific EnergyEnergy density
Upper T
Cycle life
Slide9www.DLR.de •
Chart
9
> Lithium/Sulfur Batteries: An Elementary Modeling Approach > D. N. Fronczek • ModVal 9 > April 2, 2012
Lithium/sulfur battery – layoutGlobal reaction: S8 + 16 Li ⇄ 8 Li2S + 3400 kJ/molComplex chemistry, complex multi-phase behavior!
Positive
Electrode
Negative Electrode
Separator
Lithium
(metal)
Sulfur / Carbon matrix
Organic Electrolyte
Li
+
Li
0
Discharge
Charge
S
8Li2S8
Li2S4
Li2S2Li2
SS82−
S
62−
S42−
S
2
2−
S
2−
Li
2
S
6
Current collector
Current collector
Slide10> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
A virtual Li/S battery: Modeling, simulation and computer-aided development
Introduction
Fundamentals of Li/S batteries
Modeling approachSimulation resultsOutlook & Summary
www.DLR.de
•
Chart
10
Slide11> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
Computational domain
Modeling framework:
DENIS (
detailed electrochemistry and numerical impedance simulation)*1D continuum model, 15 mesh points169 algebraic and differential equations (standard model)
y
Positive
Electrode
Separator
Negative
Electrode
www.DLR.de
•
Chart
11
*
W
. G.
Bessler
, S. Gewies, M. Vogler, A new framework for physically
based modeling of solid oxide fuel cells, Electrochimica Acta 53 (2007) 1782-1800.
Slide12> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
Governing equations
Electrochemistry (evaluated by
CANTERA
†):Rates of production and relation to currentModified Arrhenius rate expressions
Transport
in the liquid electrolyte: diluted solution
theory
Nernst-Planck-eq.
†
D. G. Goodwin et al., Cantera, http://code.google.com/p/cantera, 2001-2012.
www.DLR.de
• Chart 12
Slide13Governing equations
Evolution of Phases
‡
Production rate derived from chemical source terms
Adaptive active surfaces ( : volume fraction)Plus boundary conditions, e.g. electroneutrality
www.DLR.de
•
Chart
13> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
‡
J. P.
Neidhardt, D. N. Fronczek, T. Jahnke, T. Danner, B. Horstmann, and W. G. Bessler
, "A flexible framework for modeling multiple solid, liquid and gaseous phases in batteries and fuel cells," J. Electrochem. Soc., in press (2012)
Slide14Electrochemical model
Chemical reactions considered on the positive electrode side:
sulfur reduction precipitation
S
8(s) ⇌ S8(l) S8(l) + 2 e− ⇌ S82− 2 Li
+
+ S
8
2− ⇌ Li2S8(s) S82− + 2⁄3 e− ⇌ 4⁄3
S62− 2 Li+ + S
62− ⇌ Li2S6(s) S62− + e− ⇌
3⁄2 S42− 2 Li+ + S42− ⇌ Li2S4(s)
S42− + 2 e− ⇌ 2 S22− 2 Li+ + S22− ⇌ Li2
S2(s) S22− + 2 e− ⇌ 2 S2− 2 Li+ + S2− ⇌ Li2S(s)
Lithium plating/stripping on the negative electrode side: Li(s) ⇌ Li
+ + e−Global reaction: 16 Li + S8
⇌ 8 Li2S + 3400 kJ/mol, EMF = ~2.2 V
> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
www.DLR.de • Chart 14
* K. Kumaresan, Y. Mikhaylik and R. E. White, J. Electrochem. Soc. 155, A576 (2008)
Slide15List of parameters
www.DLR.de
•
Chart
15> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
Slide16> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
A virtual Li/S battery: Modeling, simulation and computer-aided development
Introduction
Fundamentals of Li/S batteries
Modeling approachSimulation resultsOutlook & Summary
www.DLR.de
•
Chart
16
Slide17> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
Simulated experiment
CC discharge,
CCCV
charge @ ~1/50 Cwww.DLR.de • Chart 17
Slide18www.DLR.de •
Chart
18
> Lithium/Sulfur Batteries: An Elementary Modeling Approach > D. N. Fronczek • ModVal 9 > April 2, 2012
Results: Discharge / charge profileTwo distinct stages during discharge can be reproducedExplanation: Presence of solid S8 (Phase I) or Li2S (Phase II)
CV charge phase
necessary to re-
cover full capacity
Asymmetric phasebehavior duringcharge/discharge
Slide19Results: Discharge / charge profilecompared to experiment
Experiment Simulation
www.DLR.de
•
Chart 19> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
*
N.
Cañas
, K. Hirose, N. Wagner, Ş. Sörgel and K. A. Friedrich, "In-situ XRD and electrochemical characterization of cathodes for Li-sulfur batteries“, 2
nd Ertl Symposium on Surface and Interface Chemistry, June 24–27 2012, Stuttgart, Germany, Poster.
Slide20Results: Cathode composition
The composition of the cathode varies tremendously during discharge and charge, as phases are formed and consumed
Discharge and charge are
asym
-metric processes, introducing hyster-esis into the system> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •www.DLR.de • Chart 20
0.4
0.2
0.0
1.0
Discharge
CC charge
CV charge
0.5
Slide21Results: Cathode compositioncompared to experiment
www.DLR.de
•
Chart
21> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •*N. Cañas, K. Hirose, N. Wagner, Ş. Sörgel
and K. A. Friedrich, "In-situ
XRD
and electrochemical characterization of cathodes for Li-sulfur batteries“, 2
nd Ertl Symposium on Surface and Interface Chemistry, June 24–27 2012, Stuttgart, Germany, Poster.
Li
2S [2 2 2]
S8 [2 2 2]
*
Slide22> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
Results: Concentrations
Species
concen-trations
are highly time and SOC dependantS8
and S
2−
concen-trations buffered by presence of solid phasesCurrent breaks down when electrolyte is depleted of (Poly-) sulfide ions
Discharge
← → Charge
www.DLR.de • Chart 22
Slide23Results:
I
mpedance
EIS
simulation based on physicochemical model (no equivalent circuit)*Non-ambivalent interpretation of resultsCell performs best when discharged!> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
www.DLR.de
•
Chart
23*W. G. Bessler, "Rapid impedance modeling via potential step and current relaxation simulations," J. Electrochem
. Soc. 154, B1186-B1191
Slide24Results:
I
mpedance
compared
to experiment> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •www.DLR.de • Chart 24
*
W. G.
Bessler
, "Rapid impedance modeling via potential step and current relaxation simulations," J. Electrochem. Soc. 154, B1186-B1191
Experiment Simulation
Slide25> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
A virtual Li/S battery: Modeling, simulation and computer-aided development
Introduction
Fundamentals of Li/S batteries
Modeling approachSimulation resultsOutlook & Summary
www.DLR.de
•
Chart
25
Slide26Outlook
Li/S trends:
Higher sulfur contents
Engineered
nanostructured materialsProfound understanding is paramount to successful electrode/cell designwww.DLR.de • Chart 26
> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
*
E. J. Cairns, " Beyond Lithium Ion: The Lithium/Sulfur Cell “, Beyond Lithium Ion V Meeting,
June 5
–
7, 2012, Berkeley, CA
Slide27> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
Summary
Li/S model implemented in multi-phase framework
Prediction of
voltage, current and capacityconcentrationsporosity and volume fractionsQualitative explanation oftwo distinct stages during discharge
electrochemical impedance
Toolset established for further investigations,
e.g. of degradation mechanisms
Li
S
0 500 1000 1500
Discharge capacity / Ah/kg
Sulfur
Cell voltage / V
Volume fraction
S
8
Li2S0.5
0.0
0.252.52.4
2.3
www.DLR.de • Chart 27
Slide28> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
A virtual Li/S battery: Modeling, simulation and computer-aided development
Appendix
www.DLR.de
• Chart 28
Slide29Multi-scale modeling
of
electrochemical systems
Knowledge-based advancement of fuel cells and batteries at DLR using multi-scale and multi-physics modeling and simulation methodsHead: Wolfgang G. Bessler. Group: ~10 scientists and PhD students
www.DLR.de
•
Chart
29> Lithium/Sulfur Batteries: An Elementary Modeling Approach > D. N. Fronczek • ModVal 9 > April 2, 2012
Slide30List of equations
www.DLR.de
•
Chart
30
> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
Slide31Results: Transport in the Li/S
cell
The sulfur
content
in the porous cathode changes significantly and non-uniformly during discharge and chargeSulfur is redistributed in the cell
> A virtual Li/S battery: Modeling, simulation and computer-aided development > D. N. Fronczek > Next Generation Batteries 2012 > July 19, 2012 •
www.DLR.de
•
Chart 31