View
222
Download
0
Category
Preview:
Citation preview
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 1/20
A New Vanadium Redox Flow BatteryUsing Mixed Acid Electrolytes
November 2, 2010
US DOE Energy Storage Systems (ESS) Program Review
Washington DC
Liyu Li, Soowhan Kim, Wei Wang, M. Vijayakumar, Zimin Nie, Baowei
Chen, Jianlu Zhang, Jianzhi Hu, Gordon Graff, Jun Liu, Gary Yang*
Funded by the Energy Storage Systems Program of the U.S. Department Of Energy through Pacific
Northwest National Laboratories
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 2/20
Redox Flow Battery (RFB)
A redox flow battery is a promising technology for large scale energy
storage .
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 3/20
Potential RFB Systems
-1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Standard potential (V) of redox couples
H2 evolution O2 evolutionV3+/V
2+VO2
+/VO
2+
VO2+/V
3+
Fe3+/Fe
2+
Mn3+/Mn
2+
MnO4-/MnO2
Ce+/Ce
+
Co3+/Co
2+
Cu2+/Cu
+
TiOH3+/Ti
3+
Ti+/Ti
+
Cr+/Cr
+Zn
2+
/Zn
S/S2-
Br2/Br-
BrCl2-/Br
-
Cr+/Cr
+
Cl2/Cl-
All V Redox Flow Battery
The use of vanadium in both the anolyte and catholyte effectively
eliminate the cross-contamination between the electrolytes through
the ion-exchange membrane.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 4/20
Challenges for All Vanadium Sulfate RFB
V specie Vn+, M H+, M SO42-, M Temp, oC Time for p.p.
V2+
2 6 5 -5 419 hr
2 6 5 25 Stable (>30 d)
2 6 5 40 Stable (>30 d)
V3+
2 4 5 -5 634 hr
2 4 5 25 Stable (>30 d)
2 4 5 40 Stable (>30 d)
V4+ (VO2+)
2 6 5 -5 18 hr
2 6 5 25 95 hr
2 6 5 40 Stable (>30 d)
V5+ (VO2+)
2 8 5 -5 Stable (>30 d)
2 8 5 25 Stable (>30 d)
2.2 7.8 5 40 95 hr
1.8 8.4 5 40 358 hr
Low energy density: Vn+ concentration <1.7M, decided by the low
solubility of V4+ at low temperatures and the poor stability of V5+ at high
temperatures.
Limited operation temperature window: 10 to 40oC, requiring active
electrolytes temperature management during hot/cold weathers.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 5/20
Stabili ty of Vn+ Cations in HCl Solution
Vn+ specie Vn+, M H+, M Cl-, M T, oC Time for precipitation
V2+ 2.3 5.4 10 -5 Stable (>10 d)
2.3 5.4 10 25 Stable (>10 d)2.3 5.4 10 40 Stable (>10 d)
V3+ 1.5 3.0 7.5 -5 Stable (>10 d)
1.8 3.0 8.4 -5 124 hr
2.3 3.1 10 -5 96 hr
2.3 3.1 10 25 Stable (>10 d)
2.3 3.1 10 40 Stable (>10 d)
V4+ (VO2+) 2.3 5.4 10 -5 Stable (>10 d)
2.3 5.4 10 25 Stable (>10 d)
2.3 5.4 10 40 Stable (>10 d)
V5+ (VO2+) 2.3 7.7 10 -5 Stable (>10 d)
2.3 7.7 10 25 Stable (>10 d)2.3 7.7 10 40 Stable (>10 d)
Cl- anions can effectively stabilize V5+, V4+, and V2+.
It is likely that high concentration of V2+, V3+, V4+, and V5+ cations can be
stabilized in a mixed sulfate and chloride electrolyte solution.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 6/20
Vn+ Stability in SO42—Cl- Mixed Solutions
Vn+
specie
Vn+, M T, oC Time for
precipitation
V2+ 3 -5 Stable (>10 d)
2.5 -5 Stable (>10 d)
2.5 25 Stable (>10 d)
2.5 40 Stable (>10 d)
3 40 Stable (>10 d)
V3+ 3 -5 192 hr (8 d)
2.5 -5 Stable (>10 d)
2.5 25 Stable (>10 d)
2.5 40 Stable (>10 d)
3 40 Stable (>10 d)
Vn+
specie
Vn+, M T, oC Time for
precipitation
V4+
(VO2+)
3 -5 Stable (>10 d)
2.5 -5 Stable (>10 d)
2.5 25 Stable (>10 d)
2.5 40 Stable (>10 d)
3 40 Stable (>10 d)
V5+
(VO2+)
3 -5 Stable (>10 d)
2.5 -5 Stable (>10 d)
2.5 25 Stable (>10 d)
2.5 40 Stable (>10 d)
3 40 Stable (>10 d)
2.7 V5+
0.3 V4+ 50 Stable (>10 d)
2.7 V5+
0.3 V4+
60 Stable (>10 d)
SO42-/Cl- mixtures can effectively stabilize >2.5M V5+, V4+, V3+ and V2+.
Much broad operation temperature window (-5 to 60 oC) can be achieved usingSO42-/Cl- mixed electrolytes.
The overall stability of vanadium isdecided by V3+ at low temperatures.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 7/20
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 8/20
51V in mixed acid
51V in sulfuric
acid51V in VOCl3
standard
35Cl in mixed acid
35Cl in VOCl3
35Cl in HCl
Solution Chemistry of the Mixed Electrolytes-
NMR Study
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 9/20
Temperature Dependence of VO2Cl(H2O)2 Formation
-570
-565
-560
-555
-550
-545
-540
-30 -20 -10 0 10 20 30 40 50 60Temperature,
oC
5 1 V C h e m i c a l S h i f t ( p p m )
0
10
20
30
40
50
60
70
80
5 1 V
L i n e W i d t h ( k H z )
Chemical Shift-Sulfuric Acid
Chemical Shift Mixed Acid
Line Width Sulfuric Acid
Line Width Mixed Acid
VO2Cl(H2O)2 complex starts to form in the mixed solutions when
temperatures reaching ~20oC.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 10/20
Solution Chemistry of the Mixed Electrolytes-
DFT and Stability Studies
Same V2+, V3+ and V4+ -containing structures was predictedin both electrolyte solutions: [V(H2O)6]
2+, [V(H2O)6]3+ and
[VO(H2O)5]2+.
According to SEM-EDS, and XRD analysis, in the mixed
systems, the stability of V4+
is controlled by the solubility of VOSO4, the stability of V3+ is controlled by the solubility of
V2(SO4)3 and VOCl, the stability of V2+ is controlled by the
solubil ity of VSO4.
The improvement of stabi li ty of V
2+
, V
3+
, and V
4+
in the mixedsystem over the current sulfate systems is due to the
decrease of SO42- concentration in the solutions.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 11/20
Electrochemical Properties of Mixed Solutions
-0.8 -0.4 0.0 0.4 0.8 1.2 1.6-0.4
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
2.5 M V4+
+ 2.5 M SO2-
4 + 6 M Cl
-
1.5 M V4+ + 5 M SO2-4
C u r r e n t D e n s
i t y ( A / c m
2 )
Potential (V vs. SHE)
V5+V
4+
V4+
V5+
V2+
V3+
V3+V
2+
No chlorine gas evolution.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 12/20
Electrode and Cell Reactions (T<10oC)
Cathode: VO2+ + H2O – e VO2+ + 2H+ E° = 1.00V
Anode: V3+ + e V2+ E°=-0.25V
Cell: VO2+ + H2O + V3+ VO2+ + 2H+ + V2+ E°=1.25V
Charge
Discharge
Charge
Discharge
Charge
Discharge
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 13/20
Cathode: VO2+ + Cl- + H2O – e VO2Cl + 2H+
Anode: V3+ + e V2+
Cell: VO2+ + Cl- + H2O + V3+ VO2Cl + 2H+ + V2+
Charge
Discharge
Charge
Discharge
Charge
Discharge
Electrode and Cell Reactions (T>10oC)
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 14/20
- Cell and reservoirs are inside the environmental chamber.
- Circulating pump is out side of the chamber.
- Pressure monitoring.
Cell Testing and RFB Evaluation
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 15/20
0 10 20 30 40 50 60 70 80 90 1000.6
0.8
1.0
1.2
1.4
1.6
1.8
Charging
V o l t a g e ( V )
Capacity / Charging Capacity (Ah%)
Discharging
10 15 20 25 30 35 40 45 50 5570
75
80
85
90
95
100
Coulomb Energy Voltage
E f f i c i e n
c y ( % )
Cycle Number
Stable performance with 88% energy efficiency at 50 mA.cm-2
Cell Performance at Ambient Temperature
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 16/20
70
75
80
85
90
95
100
0 10 20 30 40 50 60 70 80 90
Cycle number
E f f i c i e n c y , %
Coulombic Efficiency
Voltage Efficiency
Energy Efficiency
40oC 0
oC5
oC50
oC
A VFB with 2.5 M V mixed acid electrolyte can be operated under a
broad temperature range of 0 to 50 oC.
Redox reactions are temperature dependent.
No noticeable gas evolution over 25 days.
Cell Performance at Varied Temperatures
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 17/20
Cell Performance at Varied Current Densities
Cell operation conditions: 10 cm2 flow cell, Charged to 1.7V by 50 mA/cm2 current.
Discharge
Current,
(mA.cm -2)
Energy Density
(Wh.L-1)
Columbic
Efficiency
Energy
Efficiency
Mixed sulfate Mixed sulfate Mixed sulfate
2.5MV 3MV 1.6MV 2.5MV 3MV 1.6MV 2.5MV 3MV 1.6MV
100 36.2 39.5 22.3 0.95 0.95 0.94 0.81 0.76 0.83
75 37.5 40.8 22.4 0.96 0.96 0.94 0.84 0.81 0.85
50 38.5 41.8 22.6 0.96 0.97 0.94 0.87 0.85 0.8725 39.2 43.1 22.6 0.96 0.97 0.94 0.90 0.89 0.88
The VRBs using mixed sulafte-chloride electrolyteswere able to deliver 70 to 80% more energy than the
sulfate system, while sti ll being highly effic ient.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 18/20
A new vanadium redox flow battery with a significant improvement
over the current technology was developed.
This battery utilizes sulfate-chloride mixed electrolytes, which are
capable of dissolving 2.5 M vanadium, representing about 70%
increase in energy density over the current sulfate system.
More importantly, the new electrolyte remains stable over a wide
temperature range of -5 to 60oC, potentially eliminating the need of
energy-consuming solution temperature management.
Battery tests indicated no concern of chlorine gas evolution during the
battery operation.
Summary
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 19/20
Further Work
Optimize the mixed electrolyte for further improvement in energy
density and stability.
Demonstrate a 2.0 kWh (0.3 kW) bench-top prototype FRB with thenewly developed mixed electrolyte.
Build up strong collaborations with industry, university, and othernational laboratory partners.
Prepare for larger systems demonstration within 2-3 years.
7/23/2019 Redox Battery
http://slidepdf.com/reader/full/redox-battery 20/20
Acknowledgements
Financial support :
1. DOE Office of Electricity Delivery and Energy Reliability
Energy Storage Program (Manager: Dr. Imre Gyuk)
2. PNNL LDRD program for NMR and DFT-related work.
The NMR work was carried out at the Environmental and Molecular Science Laboratory, a national scientific user facility sponsored by
the DOE’s Office of Biological and Environmental Research (BER).
Recommended