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Battery Design LLC
Spiral Cell Modeling with
Battery Design Studio®
Robert Spotnitz
BD
Battery Design LLC
BD Battery Design LLC
Software for Battery Design and Simulation
2
Development started April 1999
Battery Design Studio®
the means to model batteries
•To analyze data
•To visualize cell designs
•To compare experiments with
models
•To visualize model results
•Database
InputModels
Output
Size
Cost
Power
Impedance
Life
Abuse, etcData
Lab
User
Battery Design LLC
BDCommon Cell Types
Pouch cell Prismatic cellRound cell
Battery Design LLC
BDCommon Cell Designs
Page 4
Negative
Post
Negative
Tabs
Positive
Tabs
Positive
Post
Package
sealant
layer
Negative
ElectrodePositive
Electrode
Separator
Pouch cell – every
electrode has a tab
For spiral
cells, how
many tabs
should be
used?
Where
should the
tabs be
spaced?
Battery Design LLC
BDCase Studies
Electrodes with 1 tab each
• Positive electrode tab position moves
• Negative electrode tab position at end of jellyroll by can
Effect of
• Cell size (18650, 26650, 36650)
• Electrochemical polarization
Using NTG model
5
Battery Design LLC
BDNTG Model
6
References
(1) J. Newman and W. Tiedemann, J. Electrochem. Soc. Vol. 140, No. 7,
July 1993 pp. 1961-1968.
(2) H. Gu, J. Electrochem. Soc., Vol. 130 No. 7 1983 pp. 1459-1464.
(3) U. S. Kim, Ch.B. Shin, C.-S. Kim, J. Power Src. 189 (2009) 841-846
dT
dUTVUAQ
DoDaDoDaDoDaadT
dU
DoDaDoDaaY
DoDaDoDaDoDaaU
A
IJ
Capacity
IdtDoDU
Y
JJDoDV
cell
cell
3
10
2
987
2
654
3
3
2
210
,,,
W ,generationHeat
Ke,Temperatur
A Current,
m area, Electrode
mS e,Conductanc
mA density,Current
V voltage,Equil.
(fraction) discharge of Depth
V voltage,cell Working
2
2
2
Q
T
I
A
Y
J
U
DoD
Vcell
Battery Design LLC
BDTab Positions
7
Tab Position
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Position of positive tab moves
Negative tab position is fixed at end
Battery Design LLC
BDSpiral Winder
Page 8
Battery Design LLC
BDCell Properties
Page 9
Value18650-p1 26650-p1 36650-p1
Active Area, m² 0.038 0.09 0.19
Active Coating Length, m 0.66 1.6 3.3
Capacity, Ahr 1.5 3.6 7.3
Energy Density, Whr/liter 327.0 374.3 402.5
Energy, Whr 5.4 12.9 26.6
Jellyroll Diameter, mm 17.6 25.5 35.5
Voltage, V 3.6 3.6 3.6
Volume, cm³ 16.5 34.5 66.1
Battery Design LLC
BDTab Positions (18650)
Page 10
0.5
0.4 0.3
0.60.8
0.1
Battery Design LLC
BD Case 1A – 20 A Discharges
11
Initial voltage drop depends on tab position
I
VOCVR
t sec1
Battery Design LLC
BDCell Resistance versus tab
position (Y=1000 S/m2)
Page 12
Battery Design LLC
BD18650 – Effect of Y
Page 13
Battery Design LLC
BD26650 – Effect of Y
Page 14
Battery Design LLC
BD18650 – LoY, Pos Plate
Voltage
Page 15
1
2
3
4
5
6
7
8
95.6 mV
62.8 mV
52.4 mV
44.4 mV
64.4 mV
41.0 mV
56.8 mV
67.3 mV
Battery Design LLC
BD18650 – LoY, Neg Plate
Voltage
Page 16
1
2
3
4
5
6
7
8
124.1 mV
124.5 mV
123.8 mV
123.9 mV
123.6 mV
92.9 mV
93.0 mV
92.9 mV
Battery Design LLC
BD18650 – LoY, Pos Inner
Current Density
Page 17
1
2
3
4
5
6
7
8
673 A/m2
660 A/m2
648 A/m2
639 A/m2
630 A/m2
611 A/m2
607 A/m2
604 A/m2
Battery Design LLC
BD18650 – LoY, Pos Outer
Current Density
Page 18
1
2
3
4
5
6
7
8 622 A/m2
626 A/m2
630 A/m2
655 A/m2
663 A/m2
672 A/m2
684 A/m2
698 A/m2
Battery Design LLC
BD18650 – LoY, Neg Plate Iin
Page 19
1
2
3
4
5
6
7
8 622 A/m2
698 A/m2
626 A/m2
630 A/m2
655 A/m2
663 A/m2
672 A/m2
684 A/m2
Battery Design LLC
BD18650 – LoY, Neg Plate Iout
Page 20
1
2
3
4
5
6
7
8
673 A/m2
613 A/m2
634 A/m2
640 A/m2
650 A/m2
663 A/m2
607 A/m2
608 A/m2
Battery Design LLC
BD26650 – LoY, Neg Plate
Inner Current Density
Page 21
1
2
3
4
5
6
7
8 297 A/m2
302 A/m2
311 A/m2
322 A/m2
335 A/m2
353 A/m2
374 A/m2
403 A/m2
Battery Design LLC
BD26650 – LoY, Neg Plate
Voltage
Page 22
1
2
3
4
5
6
7
8
161 mV
179 mV
176 mV
174 mV
167 mV
171 mV
165 mV
163 mV
Battery Design LLC
BD26650 – LoY, Pos Plate
Voltage
Page 23
1
2
3
4
5
6
7
8
192 mV
112 mV
91 mV
72 mV
60 mV
56 mV
78 mV
98 mV
Battery Design LLC
BD26650 – HiY, Pos Plate
Voltage
Page 24
1
2
3
4
5
6
7
8
133 mV
117 mV
102 mV
86 mV
55 mV
71 mV
43 mV
48 mV
Battery Design LLC
BD36650 (LoY) Plate Voltage
Page 25
Pos-1 Pos-8
Neg-1 Neg-8
146 mV
220 mV
218 mV
322 mV
Battery Design LLC
BD36650 (LoY) Iin
Page 26
Pos-1 Pos-8
Neg-1 Neg-8
308 A/m2
344 A/m2
180 A/m2
217 A/m2
Battery Design LLC
BDCircuit Model – Same end tabs
Negative
Positive
Placing tabs at same ends gives most non-uniform
current distribution, but minimizes measured voltage
drop in collectors
Echem
current
Battery Design LLC
BDCircuit Model – Opposite tabs
Negative
Positive
Placing tabs at opposite ends gives most uniform
current distribution, but maximizes measured
voltage drop in collectors
Battery Design LLC
BDCircuit Model – center tab
Negative
Positive
Placing tabs at center trades off voltage drop in collectors
and current flow through cell
Battery Design LLC
BD Summary
Optimum position of tab along the current collector depends on resistance of collectors and electrochemical resistance• Low ratio of Rechem/Rcoll favors placing tabs on
same ends, while high value favors placing tabs on opposite ends
Simulation capability for electrical distribution in spirally-wound cells developed. This tool enables simulation studies to determine optimal position of tabs and dimensions of current collectors
30
Battery Design LLC
BD Summary
Optimum position of tab along the current collector depends on resistance of collectors and electrochemical resistance• Low ratio of Rechem/Rcoll [(1/YA) / (L/A)] favors
placing tabs on same ends, while high value favors placing tabs on opposite ends
Simulation capability for electrical distribution in spirally-wound cells developed. This tool enables simulation studies to determine optimal position of tabs and dimensions of current collectors
31
Battery Design LLC
BD
BACKUP
32
Battery Design LLC
BDMultiple Tabs
Page 33
Battery Design LLC
BD26650 (LoY) Plate Voltage
Page 34
Pos-1 Pos-8
Neg-1 Neg-8
Battery Design LLC
BD26650 – HiY, Pos Plate Inner
Current Density
Page 35
1
2
3
4
5
6
7
8
133 mV
117 mV
102 mV
86 mV
55 mV
71 mV
43 mV
48 mV
Battery Design LLC
BD26650 (LoY) Iin
Page 36
Pos-1 Pos-8
Neg-1 Neg-8
Battery Design LLC
BD26650 (LoY) Iout
Page 37
Pos-1 Pos-8
Neg-1 Neg-8
