Hydrogen/BromineFlowBattery
for Grid Scale Energy Storage
forGrid‐ScaleEnergyStorage
KyuTaekCho,AdamZ.Weber,VincentBattaglia,and
Venkat Srinivasan
EnvironmentalEnergyTechnologiesDivision
Environmental
Energy Technologies Division
LawrenceBerkeleyNationalLaboratory
2013 International Battery Association Meeting
Barcelona, Spain, March 15, 2013
EnergyStorageontheGrid
(Energy Resource Council)
24h
Hours
Real Powe
er Output (kW)
MW
M
GridReliability
Seconds
 Stabilize grid power at 60Hz given intermittent generation assets  Requirements
 High power (MW)
 Fast ramp rate (seconds)
Fast ramp rate (seconds)
 High efficiency (70‐90%)
 Short discharge times (< 1 hour)
Carnegie Mellon working paper CEIC-08-04
California ISO – Integration of Renewable Resources Nov 2007
MW
RenewablesIntegration/Firming
 Time shifting of intermittent assets to high‐value periods
Time shifting of intermittent assets to high value periods
 Similar requirements to Grid Reliability, but longer discharge times (4‐8 h)
FlowBatteriesforEnergy
Storage
g
• Separation of energy and power
• Energy dictated by size of tank
• Power depends on size of cell
• Cell stack is typically expensive
Requirements:
1.Good reversibility
2. Chemicals that are inexpensive
3. Inexpensive cell components
4. Need a high power device
•Higher the power, lower the cell number
5. No structural changes (e.g., plating)
6. Good safety
Increasing power
Hydrogen/BromineFlowBattery
Br2/
HBr
H2
H2 ↔ 2H+ + 2e
Nafion or microporous
membrane
Ch
harge
Dis
scharge
Br2 + 2H+ + 2e ↔ 2HBr
Support
pp
layer
y (GDL)
Carbon paper
catalyst layer
Pt/C catalyst layer
HBr
Leveraging designs developed in
the fuel-cell field for the cell
H2/Br2 Flow Battery System
Discharge
Charge
Hydrogen
‐
Pressure Gauge
+ Br /HBr solution
Reflux
2
Br2
H2
Pump
H+
HBr
Porous media
Catalyst
Membrane
Porous media
Catalyst
FB Cell
(heating)
(‐) side
(+) side
H2 ↔ 2H+ + 2e
+ 2e
Br2 + 2H
+ 2H+ + 2e ↔
+ 2e ↔ 2HBr
In‐line filter
Heat bath
(heating)
Cell Performance
‐Electrolyte concentration
‐Operating temperature
‐Membrane
Membrane thickness
‐Electrolyte composition ‐Operating temperature
Ecell = E0 ‐ηact ‐ηohm ‐ηmass
‐Electrode material
(Pt vs Carbon)
‐Electrode activation
‐Porous electrode (wettability, permeation..)
‐Flow Rate of Electrolyte
y
‐Flow‐Field Geometry (Flow‐by vs Flow‐through)
KineticsofBr2 Reaction
 Total cell resistance = Ohmic+charge transfer+mass transfer
Membranes
and contact
Kinetically fast
reactions
Better
B
tt cellll
design
Rotating disc studies
Charge-transfer kinetics very fast. Expensive catalyst not needed.
KineticsofBr2 Reaction
 Effect of surface area on kinetics
15
GC Po
ower (as % of tthat for Pt)
10
1.7 %
5
0
-5
2.0 %
-10
Anodic reaction
Cathodic reaction
-15
-20
0
20
40
60
80
100 120 140 160 180 200
Area ratio, GC/Pt
Rotating Disk Electrode (RDE)
to measure reaction kinetics
K.Cho et al. JES 159 (11) A 1806‐A1815 (2012)
To obtain kinetically limited performance within 2% of that for a Pt‐catalyzed
a Pt
catalyzed MEA, a GC electrode requires MEA, a GC electrode requires ~20
20 times more times more
2
surface area per cm .
ElectrodeActivation
 Pretreatment
 Increase performance
Increase performance
Pretreatment
Max PD
(W/cm2)
Increase
(%)
Max CD
(A/cm2)
Increase
(%)
Baseline
0.667
0
1.196
0
H2O2
0.667
0
1.196
0
H2SO4
0.921
38
1.54
29
Heat (400C)
0.926
39
1.49
25
Br2
0.802
20
1.29
8
ElectrodeActivation
Raw
 Carbon‐electrode fibers
 Some minor damage and structural deformation
 Close up there is changes to fiber surface
Close up there is changes to fiber surface
 Due to oxidation?
Pretreated
ElectrodeActivation
 XPS measurement
 Enrichment of oxygen on surface correlates to best performing pretreatment
Enrichment of oxygen on surface correlates to best performing pretreatment
O/C=7/93 (8%)
O/C=40/60 (67%)
O/C=8/92 (9%)
Mass transfer: flow‐mode effect
(‐)
Anode
(H2)
(+)
Cathode
MEA (Br2/HBr)
x
y
z
Diffusion
H2
Br2/HBr
Flow
Convection
Diffusion
Flow
B 2/HBr
Br
/HB
(Flow‐by mode)
D. L. Wood, Y. S. Yi, and T. V. Nguyen, Electrochim. Acta, 43, 3795 (1998).
(Flow‐through mode)
Mass transfer: flow‐mode effect
 Flow through increases limiting current and high‐frequency resitance
 Membrane resistance higher than expected for Nafion in contact with liquid water
Membrane resistance higher than expected for Nafion in contact with liquid water
2
Proton resistanc
ce in memb
brane ( cm
m)
0.30
2
Flow rate: 3 ml/min.cm
2
Flow rate: 10 ml/min.cm
0 27
0.27
0.24
0.21
Fl
Flow-by
b mode
d
0.18
0.15
Flow-through
Flow
through mode
0 12
0.12
0.09
0.06
Theoretical membrane resistance
0.03
0.00
0.2
0.4
0.6
0.8
1.0
1.2
2
Current Density (A/cm )
1.4
Mass transfer: flow‐mode effect
 Model shows that indeed the flow‐through is better at removing HBr nearer to the g
y
g
membrane even though the current density is higher
 HBr concentration along cathode membrane/electrode interface at 0.8 V
 Increases due to reaction
Flow by
Flow through
OhmicResistance
 Polarization curves appear to be ohmically controlled
 Increase in resistance with decrease in state of charge
Increase in resistance with decrease in state of charge
1.2
0.20
1.0
0.6
0.6
0.4
0.4
SOC 100% (0.9M Br2 / 1M HBr)
SOC 75% ((0.73M Br2 / 1.32M HBr))
SOC 50% (0.53M Br2 / 1.72M HBr)
SOC 25% (0.29M Br2 / 2.17M HBr)
02
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
2
Current Density (A/cm )
1.4
0.18
2
0.8
ASR (Oh
hm.cm )
Cell volta
age (V)
2
0.8
Power Dens
sity (W/cm )
0.19
1.0
SOC 100% (0.9M Br2 / 1M HBr)
SOC 75% (0
(0.73M
73M Br2 / 1.32M
1 32M HBr)
SOC 50% (0.53M Br2 / 1.72M HBr)
SOC 25% (0.29M Br2 / 2.17M HBr)
0.17
0.16
0.15
0.2
0.14
0.0
1.6
0.13
0.0
0.2
0.4
0.6
0.8
1.0
1.2
2
Current density (A/cm )
1.4
1.6
Ohmic Resistance
 Membrane characterization
‘H’‐glass cell Reference
R
f
electrode
Membrane
 Conductivity decreases at higher HBr concentration
Conductivity
Ohmic Resistance
 Membrane characterization
Conductivity
Thi k
Thickness
65
Pre
etreated NR212 thickn
ness (μm)
64
63
62
61
60
59
58
57
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
HBr concentration (mol/L)
SAXS
Domain spacing
 Conductivity decreases at higher HBr concentration
 Membrane dehydrates at higher HBr concentration
OhmicResistance
 As decrease HBr, get better performance but do not want too little since need to p
complex the Br
2
1.2
1.0
0.30
0.28
1.0
0.8
0.9M Br2 / 1M HBr
4M Br2 / 4M HBr
4M Br2 / 2M HBr
4M Br2 / 1M HBr
0.6
0.6
0.4
0.4
0.9M Br2 / 1M HBr
4M Br2 / 4M HBr
4M B
Br2 / 2M HB
HBr
4M Br2 / 1M HBr
02
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
2
Current Density (A/cm )
1.2
0.2
2
0.8
ASR (Ohm
m.cm )
Cell volta
age (V)
2
Power Densitty (W/cm )
0.26
0.24
0.22
0.20
0.18
0.16
0.14
0.0
0.12
0.2
0.4
0.6
0.8
1.0
2
Current Density (A/cm )
1.2
OhmicResistance
 Decrease thickness of membrane shows increased performance
1.2
1.4
80
1.2
0.6
0.4
Nafion 175 m
Nafion
N
fi 50 m
Nafion 25 m
Reinforced 15 m
0.2
0.0
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2
Current Density (A/cm )
2.7
3.0
0.4
0.2
0.0
3.3
HFR (mOhm
m)
Cell voltage
e (V)
0.8
0.6
60
2
1.0
0.8
70
Power Density ((W/cm )
1.0
Nafion 175 m
Nafion 50 m
Nafion 25 m
Reinforced 15 m
50
40
30
20
10
0
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
2
C
Current
d
density
i (A/cm
(A/
)
2.7
3.0
3.3
Best‐of‐ClassPerformance
 Greatly improved performance with optimization of cell components
1.2
1.0
1.6
2.0
1.4
1.8
1.6
1.4
2
1.0
0.6
0.8
0.6
0.4
st
1 Generation
nd
2 Generation
rd
d
3 Generation
th
4 Generation
th
5 Generation
0.4
Cell voltage (V)
Cell voltag
ge (V)
0.8
0.2
Power Density
y (W/cm )
1.2
1.2
1.0
0.8
0.6
0.4
0.2
0.2
0.0
0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 3.6 3.9 4.2
0.0
0.0
0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 3.6 3.9 4.2
2
Current Density
y ((A/cm )
2
Current Density (A/cm )
Ambient temperature and pressure
0.9 M Br2 / 1 M HBr
Voltaic efficiency
PD (W/cm2)
i (A/cm2)
80 %
0.99
1.5
90 %
90 %
0 60
0.60
0 65
0.65
TotalUtilization
2.4
Cell: SPFF|25BC||Pt/C|N211||GFD-3|FLTHRU
2.0
Br2: 0.9 M
HBr: 1.0 M
Cell vo
oltage (V)
0.80
1.6
HBr
0.60
1.2
0.8
0.40
Br2
0.4
0.9 M Br2/ 1 M HBr at 300ml/min
Const.Current: 3.5A (80% efficiency)
0.20
0
1
2
3
4
Discharge duration (hrs)
Bromine utilization: ~93%
5
Concen
ntration (Brr2 and HBr), mol/liter
1.00
0.0
4.597 hrs
(Br2: 0.058 M
HBr: 2.32 M))
23
CostModel
(Capital cost as a function of discharge time)
1000
900
Gen 1
Gen 2
Gen 3
Gen 4
Gen 5
Nafion only
Batte
ery capital cosst ($/kWh)
800
700
600
500
400
300
Gen 5, 1h, is
at 664 $/kWh
200
100
0
0
1
2
3
4
5
Discharge time (h)
6
7
8
Note: The cost model results shown here do not include components that may eventually be required to handle species crossover.
24
Cell stabilit
Cell stability
Cathodic Protection
Test condition: Polarize MEA to hydrogen evolution potential and hold at 0.2 mA/cm2 cathodic current.
Pt dissolution rate (mg/hr)
0.25
Cathodically
y Protected
MEA immersed in 48% HBr
Unprotected
0.2
0.15
Cathodically
y
Protected
0.1
0.05
0
MEA ‘A’
NSTF
MEA
Ion MEA ‘B’
Power MEA
 The
The rate of platinum dissolution from the membrane is greatly diminished at the rate of platinum dissolution from the membrane is greatly diminished at the
hydrogen electrode potential
Cathodic Protection
 Cell voltage variation after shutdown but with small hydrogen supply
 Negligible performance change
Negligible performance change
 Keep hydrogen at the negative electrode!
12
1.2
08
0.8
0.7
1.0
Cell volltage (V)
2
0.8
0.5
0.6
0.4
0.3
0.4
0.2
02
0.2
0.0
0.0
Power Dens
sity (W/cm )
0.6
Before OCV decay test
After OCV decay for 24hrs
0.2
0.4
0.6
0.8
2
Current Density (A/cm )
0.1
0.0
1.0
Preliminary Cycling Data
20
2.0
100
90
80
70
1.6
60
50
40
1.4
30
Discharge capacity
Energy efficiency
Coloumbic efficiency
1.2
1.0
0
2
4
6
8
10
12
No. Cycle
14
16
18
20
10
0
20
Efficien
ncy (%)
Discharge capacity (Ah))
D
1.8
Coulombic efficiency: 98 %
E
Energy efficiency: 80 %
ffi i
80 %
Decay of capacity: ‐3.8mAh/cycle
RecoverableDecay
0.9
1.8
0.8
1.6
0.7
1.4
0.6
0.6
0.5
04
0.4
0.4
0.3
Initial performance
after 1st C/D full pol. test
after 2nd C/D full pol. test
after 3rd C/D full p
pol. test
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
2
Current Density (A/cm )
1.2
0.2
0.1
0.0
1.4
Cell v
voltage (V)
Cell v
voltage (V)
0.8
2.0
2
1.0
1.0
Power Density (W/cm )
1.2
Discharge performance after cycling tests
cycling tests
Charge/Discharge performance after cycling tests
after cycling tests
1.2
Charge
1.0
08
0.8
Discharge
0.6
1st C/D full pol. test
2nd C/D full pol. test
3rd C/D full pol. test
4th C/D full p
pol. test
0.4
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
2
Current Density (A/cm )
 Cell performance was recovered after full polarization tests
1.2
1.4
RecoverableDecay
 Performance was not decayed after 3‐week continuous C/D cycle test
1.2
1.0
0.9
1.0
Cell voltag
ge (V)
0.6
0.5
0.6
0.4
0.4
0.3
IInitial
iti l performance
f
One week C/D continuous test
Two weeks C/D continuous test
Three weeks C/D continuous test
0.2
0.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
2
Current Density (A/cm )
1.4
0.2
0.1
0.0
1.6
2
0.7
0.8
Power Density
P
y (W/cm )
08
0.8
Summary
Ecell = E0 ‐ηact ‐ηohm ‐ηmass
 Improved cell performance
 Electrode for Br2 side: activated carbon porous electrode with enough surface area
 Membrane: thinner, reinforced PFSA membrane
 Flow mode: flow‐through flow mode
 Cell performance: 1.5 W/cm2
Cell performance 1 5 W/cm2 (peak power) and 4 A/cm2 (limiting current) at room temp.
(peak po er) and 4 A/cm2 (limiting c rrent) at room temp
 Cell stability/durability
Cell stability/durability
 Negligible OCV decay with hydrogen on negative electrode  Negligible performance decay after 3 weeks continuous C/D cyclic tests  Cyclic performance
 Some decay of capacity from preliminary cyclic tests
Some decay of capacity from preliminary cyclic tests
Still more work to be done…
Acknowledgements
 Membrane characterization
 Rafael A. Prato (UC Santa Barbara), Ahmet
Rafael A Prato (UC Santa Barbara) Ahmet Kusoglu (LBNL) (LBNL)
 XPS measurement : Xiaofang Yang (Princeton University)
 Kinetic Measurements
 Paul Ridgway (LBNL)
 Cost Model
 Paul Albertus (Bosch)
 Funding
 US DOE ARPA‐E
US DOE ARPA E
 Robert Bosch Corp.
 ALS: DOE OS
K.Cho et al. JES 159 (11) A 1806‐A1815 (2012)
H2/Fe‐ion
Discha
arge Power
2
Densitty (mW/cm )
200
150
100
First literature performance
50
0
1.2
Voltage (V
V)
1.0
08
0.8
0.9MFeCl3 2M HCl
0.6
Flow-through
0.4
0.2
0.0
0 7M Fe2(SO4)3
0.7M
0.8M H2SO4
0.9MFeCl3 0.8M HCl
Flow-by
Flow-by
0
100 200 300 400 500
2
Current Density (mA/cm )
600
* Fatih, K, D.P. Wilkinson, F. Moraw, A. Ilicic, and F. Girard, Electrochem. Solid-State Lett., 11(2) B11-B15 (2008).