Design of a spatially resolved electro-thermal model for lithium-ion pouch cells

20 Pages·2013·2.34 MB·English

ANSYS Conference & 31th CADFEM Users‘ Meeting 2013
June 19-21, 2013 – Rosengarten Mannheim
Design of a spatially resolved electro-thermal model
for lithium-ion pouch cells
S. Stumpp, C. Günther, M.A. Danzer
Zentrum für Sonnenenergie- und Wasserstoff-Forschung
Baden-Württemberg (ZSW), Ulm, Germany
L. Kostetzer, E.Rudnyi
CADFEM GmbH, Grafing bei München, Germany
Outline
Introduction to lithium-ion cells
•
Applications and requirements
•
Theoretical background
•
Functional principle and basic design
•
Temperature influence on performance
•
Safety risks
Spatially resolved electro-thermal model
for a large size lithium-ion pouch cell
Parameterisation
•
Sensitivity analysis
Results of parameterisation
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim
Introduction to lithium-ion cells
Applications
Lithium-ion-technology for rechargeable batteries
•
Highest energy- and power density of commercially available cells
Applications
Consumer electronics Power tools and gardening tools
• •
Mobile phones Drill
• •
Laptop Chainsaw
Energy storage systems Electric vehicles
• •
Domestic BEV
• •
Grid services HEV
Requirements
•
Lightweight
•
Low cost
•
Long life
•
Safe operation
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim
Introduction to lithium-ion cells
Theoretical background
Basic design of secondary batteries
charge
current collector (Al)
+
cathode
soaked with
Li+
separator
electrolyte Li+
anode
-
current collector (Cu)
discharge
Electro-chemical reactions
•
anode/cathode: graphite/LiCoO
2
Anode: 0.6 C + 0.6 Li+ + 0.6 e-« 0.6 LiC
6 6
Cathode: LiCoO « Li CoO + 0.6 Li++ 0.6 e-
2 0.4 2
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Overall: LiCoO + 0.6 C « Li CoO + 0.6 LiC
2 6 0.4 2 6
Transport mechanisms [1]
•
Electrons
= - s (cid:209) j
• Ohmic law j
el
•
Ions
• Migration = - m (cid:209) j
N z Fc
mig
• Diffusion N = - D(cid:209) c
diff
[1]: Newman, “Electrochemical Systems”, Wiley, 2004
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim
Introduction to lithium-ion cells
Temperature influence
Performance
•
Temperature-dependent parameters like ionic conductivity [2]
•
Arrhenius-equation:
 
E 1 1
A - 
Parameter P  
P = P e R Tref T 
0
Degradation at elevated temperatures
•
Increase of internal resistance [3,4]
•
Decrease of capacity [3,5]
Safety risks through “Thermal runaway”
•
Temperature as trigger for exothermic reactions [6]
•
Rate of reaction R
E
- A
R ~ ce RT
•
Triggering of reactions with higher activation energy
due to temperature rise induced by heat release of reactions
[2]: Guet al., J ElectrochemSoc, 147, p. 2910, 2000 [3]: Amine et al., Electrochemistry Comm, 7, p. 669-673, 2005
[4]: Amine et al., J Power Sources, 97-98, p. 684-687, 2001 [5]: Amine et al., J Power Sources, 129, p.14-19, 2004
[6]: Kim et al., J Power Sources, 170, p. 476-489, 2007
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim
Introduction to lithium-ion cells
Temperature influence
Inhomogeneous degradation caused by cooling strategy:
•
Accelerated aging in hotter regions of the cell [7]
Electro-thermal interaction in cells and modules [8, 9]
•
Increased current through hotter cells/regions
•
Inhomogeneous distributions
•
Current density
•
State of charge
•
Cell potential
•
Heat generation
⇒ Battery management systems with thermal management [10]
⇒ Electro-thermal models for design of battery packs
[7]: Gerschleret al., VPPC, Dearborn, 2009 [8]: Fleckenstein et al., J Power Sources, 196, p. 4769-4778, 2011
[9]: Verbrugge, AlChEJournal, 41, p. 1550-1562, 1995 [10]: Bandhauer, J ElectrochemSoc, 158, p. R1, 2011
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim
Spatially resolved electro-thermal model
for a large size lithium-ion pouch cell
Schematic of cell Schematic of electrodes
II
BBaatt
UU
BBaatt
Electrical model [11,12]
R R
Network of resistors
elec.,i,pos. elec.,j,pos.
R
•
Discretisation of conducting components tab,pos.
•
Reproduction of current paths
Electro-chemical subcells
•
Lumped model for
electro-chemical impedance [7]
subcell
R
tab,neg. R R
elec.,i,neg. elec.,j,neg.
[7]: Gerschleret al., VPPC, Dearborn, 2009
[11]: Stumppet al., Advanced Battery Power, Münster, 2012
[12]: Stumppet al., Modval, Bad Boll, 2013
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim
Spatially resolved electro-thermal model
for a large size lithium-ion pouch cell
Thermal model [11,13] Geometry of the cell
Cell
•
Geometry
•
Implemented in ANSYS Mechanical
•
Thermal analysis
• FEM  ¶ T  ( r )
r c  - (cid:209) s (cid:209) T = h + q& Tabs
• Heat equation [14] p ¶ vol surf
 t 
•
Isotropic heat conductivity
•
Tabs Pouchbag foil
•
Orthotropic heat conductivity
of composite materials
•
Pouchbag foil
•
Stack of electrodes
Stack of electrodes
•
Boundaries
•
Temperatures at tabs
•
Convection at surface
[11]: Stumppet al., Advanced Battery Power, Münster, 2012
[13]: Kostetzer, “Battery Pack Electro-thermal Simulation”, Master thesis, Ingolstadt-Landshut, 2011
[14]: ANSYS Release 14 Theory Reference, 2011
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim
Spatially resolved electro-thermal model
for a large size lithium-ion pouch cell
Electro-thermal model
Coupling of electrical and thermal model
Transfer of heat release
•
Calculated by electrical model
•
Input for thermal model
Heat generation
•
Tabs
•
Electrode stack
Mechanisms
•
Joule heat
•
Reversible heat
Similar work based on FEM: [15]
[15]: Kostetzeret al., Simvec, Baden-Baden, 2012
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim
Spatially resolved electro-thermal model
for a large size lithium-ion pouch cell
Implementation of electro-thermal model
Input signals
Thermal model
•
Cell current
in ANSYS Mechanical
•
Temperatures
•
Tabs
• MOR4ANSYS
Ambient air
Classes of output signals Electro-thermal model { }
 Q&  Thermal model
• Cell states in Matlab  
T  MOR-matrices
•  tab,negfi u
Subcell branches
Ttab,pos x& = Ax +Bu
• Electrode branches  T 
amb
=
y C x
Accessible properties
In Out
•
Temperature
• { T } = { T T … } ∫{I}dt
• 1 2 {SOC}= +{SOC}
Current C i
N,Elem
•
SOC
{ }
• Heat release Electrical parameters T ‹ y
• Potential f(SOC,T)
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S. Stumpp | ZSW | ANSYS Conference & 31th CADFEM Users' Meeting 2013 | June 19-21, 2013 | Rosengarten Mannheim