Highly Stable Anion-Exchange Membranes for High-Voltage ...1/31/2016: Less than 5% of multiple...

Highly Stable Anion-Exchange Membranes for High-Voltage Redox-Flow Batteries

2016 DOE Hydrogen and Fuel Cells Program Review

Yushan Yan (PI)

June 8, 2016

FC131

This presentation does not contain any proprietary, confidential, or otherwise restricted information

Overview

Timeline

• Start: June 1, 2015• End: May 31, 2017• % complete: ~45%

Barriers

Partners – Principle InvestigatorsBudget ($K)

• Durability (Oxidative Stability of Membrane)• Performance (Ion Conductivity)• Cost

University of Delaware

• University of Delaware – Yushan Yan, Shuang Gu, Bingjun Xu

• National Renewable Energy Laboratory – Bryan Pivovar

• UD, $500 K• NREL, $100 K• Total Project Budget $750K

($600K DOE Share + $150K Cost Share)

2

RelevanceObjectives & Relevance


Objectives:

Relevance:

• Develop a class of anion-exchange membranes (AEMs) with very high oxidation resistance for high-voltage cerium redox-flow batteries (RFBs), and other alkaline membrane-based electrochemical devices such as fuel cells and electrolyzers

• Gain new knowledge of polymer chemistry and membrane technology that will help advance the design and development of polymer electrolytes for electrochemical devices

• With voltages more than double the voltage of standard all-vanadium RFBs, cerium RFBs hold the potential to offer high-performance and low-cost electricity storage solution for renewable energy.

• Stable AEMs can also be used for hydroxide exchange membrane fuel cells (HEMFCs), which will improve the cell durability and performance (e.g., operating at elevated temperatures). Another potential application of stable AEMs is in alkaline membrane electrolyzers for renewable hydrogen production.

• Stable AEMs are the key missing element in making cerium RFBs a viable technology. Stable membranes are also necessary to achieve highly durable AEM electrolyzers, which will lower the cost for hydrogen production.

3


ApproachProject Milestones

No. Due Date Milestones Status

M1.1 10/30/2015 Less than 10% loss of initial weight for the identified polymer at 40 °C for 1000 h in 0.5 M Ce(Ⅳ)(ClO4)4

Completed on time

M1.2 1/31/2016 Less than 5% of multiple brominated 9MeTTP+ cation based on 1H and 31P NMR spectroscopy

Completed on time

M1.3 4/30/2016 More than 95% purity for synthesized 9MeTTP+ - functionalized polymers based on 1H and 31P NMR spectroscopy

Completed on time

M1.4 7/31/2016 Less than 20% loss of initial IEC for 9MeTTP+ -functionalized polymers at an accelerated degradation test at 40 °C for 1000 h in 0.5 M Ce(Ⅳ)(ClO4)4

To be performed

4


ApproachHigh voltage aqueous redox flow batteries, ARPA-E OPEN 2012

• Single-membrane design• Cannot effectively separate

anion and cation• Cannot effectively separate

acid and base

• Requires double-membrane design

Concept of double-membrane RFB

Zn-Ce RFB

5


ApproachAlkaline Stability of 9MeTTP+

0 20 40 60 80 100 120 140 160 180 200 2200

10

20

30

40

50

60

70

80

90

100

110

Perc

ent c

atio

n re

mai

ning

/ %

Time / day

9MeTTP+

9MeOTTP+-1 9MeOTTP+-2 BTMA

P

N

P

OMe

OMeMeO

OMeMeO

OMe MeO

MeOOMe

P

OMe

OMeMeO

OMeMeO

OMe MeO

MeOOMe

CH2

9MeTTP+

9MeOTTP+-1

9MeOTTP+-2

BTMA

1 M KOD solution, 80 °C, MeOD/D2O = 5/1 (vol). 31P NMR spectroscopy was used to determine the degree of degradation for all phosphoniumcations, and 1H NMR spectroscopy for ammonium cation.

6


ApproachOxidation Stability of 9MeTTP+

X

P

X

P

OMe

OMeMeO

OMeMeO

OMe MeO

MeOOMe

˃˃Highly oxidation-resistant

Phosphoniumcation

9MeTTP+

9MeOTTP+

BTMAN

Test conditions: 10 mMas test cation concentration, 0.3 M Ce(IV)(ClO4) 4 containing 0.1 M HClO4 as test cerium electrolyte, 20 °C as test temperature, and 12 h as test time. (A) BTMA+-containing solution sample before the stability test (left) and after the test (right). (B) 9MeOTTP+-containing solution sample before the stability test (left) and after the test (right). (C) 9MeTTP+-containing solution sample before the stability test (left) and after the test (right).

˃˃

7

Accomplishments and ProgressPolymer Backbone Oxidation Stability test result


Stability test of polymer membranes:

the weight of dry PSf membrane (W1, g) was measured first, and then the membrane was immersed in 0.5 M Ce(IV)(ClO4)4 solution at 40 °C. After 500 h and 1000 h, the membrane was taken out and washed with DI water several times to remove the residual salts. The weight of the membrane (W2, g) was measured after drying under vacuum at 80 °C for 24 h. The weight loss (WL) of membrane was calculated by:

𝑊𝑊𝑊𝑊 (%) = (𝑊𝑊1 −𝑊𝑊2 ⁄) 𝑊𝑊1 × 100%

8


Accomplishments and ProgressProposed Direct Quaternization through Central Phosphorus Atom

O O S

O

On

O O S

O

On

Cl

O

I

I

O

O O S

O

On

O

P

P

I

(PSf)

(ICPSf)

(9MeTTPICPSf)

DA = 60%

Temperature Molar ratio(phosphine/polymer)

Solvent Time Degree of quaternization

60 oC 2 CHCl3 5 h 080 oC 2 ClCH2CH2Cl 5 h 080 oC 5 ClCH2CH2Cl 24 h 0

120 oC 2 Cl2CHCHCl2 5 h 0

DA = 58%

Temperature Molar ratio(phosphine/polymer)

Solvent Time Degree of quaternization

20 oC 2.5 CHCl3 12 h 060 oC 2.5 CHCl3 12 h 080 oC 2.5 ClCH2CH2Cl 12 h 0

PO n

I

O

O n

O

P

I

PO n

O

I

O n

O

P

I

9


Accomplishments and ProgressNew Proposed Synthetic Strategy for Attaching 9MeTTP+ Cation to PSf

P

P

I

P

I

Br

+

P

I

CH3I

PA, TMSCl, SnCl4

NBS, BPO

O O S

O

On

NH

O O S

O

On

Cl

O O S

O

On

O O S

O

On

N

THF, r.t., 24 h

TCE, 140 °C

, 24 h

CHCl3, 55 °C, 96

h

C4H9NH2, Cs2CO3NMP, r.t., 72h

NMP, r.t., 72hCs2CO3

(CMPSf, DC =

90%)

(BAPSf, DA =

90%)

(9MeTTPPSf, DS =

90%, IEC =

0.9 mmol/g)

(PSf)

10


Accomplishments and ProgressBromination of 9MeTTP+ cation investigation

Entry 9MeTPP+

(mmol)NBSa

(mmol)BPOb

(mmol)TCEc

(ml)T

(°C)Time

(hour)DBd

(%)

1 1 1 0.05 10 80 24 0

2 1 1 0.05 10 140 24 5

3 1 1 0.05 10 140 48 5

4 1 1 0.1 20 100 20 0

5 1 1.5 0.15 20 100 20 0

6 1 1.5 0.15 20 80 20 0

7 1 2 0.2 12 140 24 25

8 1 3 0.3 10 140 24 30

9 1 3 0.3 3 140 24 33

10 1 5 0.5 12 140 24 40

11 1 5 0.5 10 140 24 50

12 1 5 0.5 3 140 24 100

a. N-Bromosuccinimide (NBS) was used as bromination reagent; b. Benzoyl peroxide (BPO) was used as radical initiator; c. Tetrachloroethane (TCE) was used as solvent; d. Degree of total bromination.

1H NMR of Entry 9, DMSO solvent

P+

I-

Br

P+

I-

12

3 4

15

432

1’3’

1 5

3, 3’

2

DMSO

H2O

1’ 4

1H NMR, CDCl3 solvent

P+

I-

12

3 3

1 4

42

CDCl3 TMS

11


Accomplishments and ProgressBromination of 9MeTTP+ cation result

• In 1H NMR spectrum, the peak at 4.71 ppm indicate the methylene group adjacent to bromine and benzene. The degree of bromination (DB) is calculated from the 1H NMR spectrum as the following equation:

DB =3A5

2A4× 100%

• In 31P NMR spectrum, there are two peaks indicate mono-brominated 9MeTPP+ cation and non-brominated 9MeTPP+

cation respectively. The integration ratio of these 2 peaks is approximately 1:2, which is consistent with the 33% DB. No signal of the multiple brominated 9MeTPP+ cation can be found.

1H NMR

31P NMR

P+

I-

Br

P+

I-

P+

I-

Br

P+

I-

12

3 4

15

432

1’

3’

1 5

3, 3’

2

DMSO

H2O

1’ 4

H3PO4

12


Accomplishments and Progress9MeTTP+ - functionalized polymer

P

I

O O S

O

On

N

TOPO

9MeTTPPSf

1H NMR

31P NMR

IR

1

2

34

5

6 7

8

10 11 1213

14

15

16

1718

9

2

3

45

1, 6-111213

14

1516

17 18

H2O

DMSO

2500 2400 2300 2200 2100 2000 1900 1800 1700 1600 1500 1400 1300

Wavenumber (cm-1)

CMPSf BAPSf Br9MeTTP+ 9MeTTPPSf

1700 cm-1 P-Ar stretching 1670 cm-1 P-Ar stretching

13


Accomplishments and ProgressBAPSf membrane oxidation stability test

P

I

Br

+

P

I

O O S

O

On

NH

O O S

O

On

N

BAPSf, DA =

90%, IEC =

1.6 mmol/g

O O S

O

On

NH2+

BAPSf (IEC

= 1.6

mmol/g) in

0.3

M

Ce(ClO4)4 and

0.1

M

HClO4

200 h 400 h

BAPSf(IEC = 1.6)

~10% degradation in H NMR break

14


Accomplishments and Progress9MeTTP+ - functionalized polymer based on 6FPBI backbone

P

P

I

P

I

Br

+

CH3I

NBS/BPO

NH2

NH2H2N

H2NCF3

CF3

COOHHOOC+

N

NH

N

HN CF3

CF3n

NaHN

N N

HN CF3

CF3n

P+

PPA, 200 °C, 72

h

THF, r.t., 24 h

TCE, 140 °C

, 24 h

1H NMR 6FPBI

N

NH

N

HN CF3

CF3n

1

1

223

34

45

6

5, 6

(Br9MeTTP+ synthesized)

(6FPBI synthesized)

(9MeTTPPBI yet to be synthesized)

15

Collaborations


Institutions Role

University of Delaware:Yushan Yan (PI), Shuang Gu, Bingjun Xu

Prime; Oversees the project, lead AEMsynthesis and characterization

National Renewable Energy Laboratory (NREL):Bryan Pivovar (PI)

Sub; Test membrane durability and prepare MEA and MEA testing

16

Future Work/Remaining Challenges


9MeTTP+ Bromination:

Polymer Backbone:

Membrane Casting:

RFB/Fuel Cell Testing:

• Increase the degree of single bromination• Avoid multiple bromination product in large scale synthesis

• Overcome compromised oxidation stability due to hydrophilic functional groups

• Test 9MeTTP+ - functionalized polymer membranes in RFB/Fuel Cell

• Address the brittle membrane due to crosslinking and large sized 9MeTTP+ cation

17

Summary


• Relevance: Developing highly stable anion-exchange membranes for high-voltage redox-flow batteries.

• Approach: Developing anion-exchange membrane based on 9MeTTP+ cation.

• Accomplishments and Progress: The project has explored multiple chemistries for connecting 9MeTTP+ to a commercial polymer backbone. The direct quaternization method through central phosphorus atom has been proved to be infeasible due to the high steric hindrance of the 9MeTTP molecule. We have devised a new synthesis strategy through brominated 9MeTTP+ cation, and obtained the desired 9MeTTP+ -functionalized polysulfone. In order to further improve the oxidation stability of the polymer, a 9MeTTP+ - functionalized 6FPBIpolymer is under investigation.

• Collaborations: We have obtained some new polymers from RPI that might be stable toward oxidation.

• Future Research: Focus on improving the conversion of the bromination of 9MeTTP+; improve the membrane property; and explore other MeTTP+ that may be more conducive to mono-bromination with high conversion.

18


Technical Backup Slides

19


Accomplishments and ProgressBromination of 9MeTTP+ cation

P+

I-

Br1

1 5

5

4

4

3, 3’

3

2

2

DMSO

H2O

1’3’

1’

P+

I-

12

34

33%67%

1H NMR, DMSO solvent, enlarged of NMR in page 11

20


Accomplishments and ProgressBromination of 9MeTTP+ cation

P+

I-

Br

P+

I-

Mono-Br 9MeTTP+

9MeTTP+

H3PO4

31P NMR, DMSO solvent, enlarged of NMR in Page 12

21


Accomplishments and ProgressBromination of 9MeTTP+ cation result

P+

I-

P+

I-

P+

I-

Br

P+

I-

Br

P+

I-

Br

Br

31P NMR, DMSO solvent, enlarged of NMR in Page 12

31P NMR, DMSO solvent

22



P

I

O O S

O

On

N

12

2

3

3

4

4

5

5

6

1, 6-11

7

8

9 10 11 12

12

13

13

14

14

15

15

16

16

17

17

18

18

H2O

DMSO

1H NMR, DMSO solvent, enlarged of NMR in Page 13

23



IR of CMPSf, BAPSf, Br9MeTTPI, and 9MeTTPPSf, full spectrum of IR in page 131700 cm-1 P-Ar stretching

1670 cm-1 P-Ar stretching

24

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