research article a quaternized polysulfone membrane for...

Research ArticleA Quaternized Polysulfone Membrane forZinc-Bromine Redox Flow Battery

Mingqiang Li Hang Su Qinggang Qiu Guang Zhao Yu Sun and Wenjun Song

School of Energy and Power Engineering Dalian University of Technology Dalian 116023 China

Correspondence should be addressed to Mingqiang Li limingqiang918sohucom

Received 13 February 2014 Revised 25 April 2014 Accepted 30 April 2014 Published 15 May 2014

Academic Editor Ying Zhou

Copyright copy 2014 Mingqiang Li et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

A quaternized polysulfone (QNPSU) composite membrane is fabricated for zinc-bromine redox flow battery The structure of themembrane is examined by FT-IR spectra and SEMThe conductivity of the membrane is tested by electrochemical analyzer Aftera zinc-bromine battery with this composite membrane is operated at different voltage while charging and at different current whiledischarging to examine the performance of themembrane it is found that the discharge voltage was 09672V and the power densitywas 6mWcm2 at a current of 01 A which indicated that the novel compositemembrane is a promisingmaterial for the flow battery

1 Introduction

Recently many people have focused on the zinc-bromineredox flow battery because it is considered highly fasci-nating for energy storage Because Zn-Br flow battery hasan advantage in cost [1] the cost of electrolyte to a greatextent determines the overall cost of the battery Zinc as avery common metal is of low cost and abundant And thebromine can be extracted in sewage and swamp Moreoverzinc-bromine battery is of high energy density and powerdensity as well as good charge and discharge properties[2ndash5] Although up to now too many experiments havebeen carried out there are still a few technical problemsunresolved [6 7] The problems are the fact that brominediffusion towards the zinc electrode could not be completelyworked out so far In the zinc-bromine redox flow batterythe membrane with good properties in ionic conductivitymechanical strength and chemical stability is required [8ndash12] However up to now the fabrication of this kind ofmembrane is very challenging

In this paper we prepared a thin quaternized polysulfone(QNPSU) composite membrane for zinc-bromine redox flowbattery which to our knowledge has not been reportedpreviously QNPSU composite membrane provides goodmechanical strengthswith low costThe initial results indicatethat the new membrane is a promising material for zinc-bromine redox flow battery

2 Experimental

21 The Composition of Chloromethyl Ethyl Ether The proce-dure for chloromethyl ethyl ether preparation was as followsFormaldehyde solution (50 g) was dissolved in the alcoholwith a volume of 30mL in a reaction kettle equipped withmixer dropping funnel and then thermometer 525 g phos-phorus trichloride was added to the solution with magneticstirring in ice bath Temperature was controlled ranging from30∘C to 35∘C and stirring continued for one hour Keepingstill for 10minutes the solutionwas separated into two layersUpper solution was chloromethyl ethyl ether which is whatwe need

The equation is given as follows

CH2O + C

2H5OH + 13

PCl3+H2O

= ClCH2OC2H5+

1

3

H3PO3

(1)

22 Chloromethylated Polysulfone Preparation The synthesisof Chloromethylated polysulfone (CMPFS) was preparedaccording to a modification of a published procedure [13]First 7 g polysulfone was dissolved in 100 cm3 (mL) 12-dichloroethane with magnetic stirring at room temperature05 g zinc chloride anhydrous was added to the above-mentioned 10mL chloromethyl ethyl etherThis solution was

Hindawi Publishing CorporationJournal of ChemistryVolume 2014 Article ID 321629 5 pageshttpdxdoiorg1011552014321629

2 Journal of Chemistry

(Catalyst)

CH3 CH3

O

SOO

O

O

SOO

O

ZnCl2ClCH2OCH2CH3

CH2Cl CH2Cl

CH3 CH3

Scheme 1 Preparation of the chloromethylation of polysulfone

added dropwise into the reaction kettle and the reactionproceeded for 8 h at 70∘C The final reaction solution waslight red The white product was precipitated in hot waterThe resulted step was dried in high vacuum to remove anyresidual solvent and kept in a vacuum before further use

The preparation of the chloromethylation of polysulfoneis as shown in Scheme 1

23 Preparation of CMPFSCompositeMembrane 5 gCMPFSwas dissolved in 30 cm3 (mL) N-methyl-2-pyrrolidone(NMP) and then the mixture was stirred at 60∘C Compositemembranes of CMPFS were prepared by CMPFS-NMPsolution evenly spreading on the glass for 30min at 60∘C andthen dried at 100∘C

24 Preparation of the Quaternized Polysulfone MembraneTheprocedure for the preparation of the quaternized polysul-fone membrane was as followsThe composite membranes ofCMPFSwere bathed in 100 cm3 (mL) trimethylamine (TMA)till the membranes softened Then the membrane was rinsedwith copious amounts of deionised (DI) water immersed inaqueous NaOH (10moldm3) solution for 12 h at 25∘C andthen dried

The preparation of the quaternized polysulfone mem-brane is as shown in Scheme 2

25 ConductivityMeasurement Membrane conductivity wasmeasured with a four-point probe and frequency responseelectrochemical analyzer CHI604D (Shanghai ChenhuaInstrument Co Ltd) The polymer membranes were held atthe desired temperature and humidity for 05 h to ensure thata steady state was achieved and measurements were taken at1min intervals

26 Battery Tests Themembranes were cut into 4 cm times 4 cmHigh-density graphite plates are used directly as frameworkcomponents and electrodesThere is a 5mmdepth slot on oneside of graphite plates to make solution circulate smoothly

CH3 CH3

CH3 CH3

O

SOO

O

O

SOO

O

N(CH3)3

CH2Cl CH2Cl

CH3N(CH3)3Clminusminus++

(CH3 )3NCH3Cl

Scheme 2 The preparation of the quaternized polysulfone mem-brane

500 1000 1500 2000 2500 3000 3500 40000

20

40

60

80

100

Tran

smitt

ance

() 3380

2970

1220

1325

Wavenumbers (cmminus1)

Figure 1 FT-IR spectra of quaternized polysulfone membrane

Themolarities of zinc-bromine solution are about 4molL sothat the amount is nearly half of the optimal value not only forthe conductivity but also for the bromine solubility [14ndash17]The anode and cathode electrodes were filled with electrolytethrough constant pumping

This research carried out the battery charging and dis-charging tests through battery testing system 75X (NewareCo Ltd)The charge was conducted by a designated currentwhile the discharge was at a constant current

3 Results and Discussion

31 FT-IR Analysis Figure 1 shows the infrared spectra ofquaternized polysulfone membrane We can find that S=Ovibration peaks are at 1220 and 1325 cmminus1 [18] The broadpeak at around 3380 cmminus1 was attributed byOndashHand residualwaterThe quaternary ammonium group stretching vibrationpeaks are at 2970 cmminus1 [19] The data suggests that there wasa successful synthesis of quaternized polysulfone compositemembrane

Journal of Chemistry 3

(a) (b)

(c)

Figure 2 SEM image of the cross-sectional quaternized polysulfone membrane

32 Morphology of QNPSU Composite Membrane Figure 2shows an image of the microporous structure of the com-posite membrane From the dense structure of compositemembrane cross-section in different magnification we cansee that themembrane cross-sectionwas comparatively denseand no holes were produced

33 Proton Conductivity of the Quaternized Polysulfone ACimpedance diagram includes frequency real part and imagi-nary partThe real parts of impedance serve as the horizontalaxis and the imaginary parts serve as the vertical axis namely119885 = 119885

1015840+ 11989511988510158401015840 The AC impedance curve is as shown in

Figure 3 Internal resistance of the battery is about 05Ω andthe conductivity of the membrane is about 001 Scm in 25∘Cwith 100 RH

34 Ions Permeability Experiments Two different kinds ofmembranes are prepared for the permeability experimentsnamely commercialNafionmembrane andquaternized poly-sulfone composite membrane Experimental procedure is asfollows 20mLbrominewaterwith a certainmolar concentra-tion is contained in a sealed container and the bottom of thecontainer is quaternized polysulfone composite membranewhich is pasted onto the container to let ions cross throughit Then we put the container into a bottle and seal the bottleAfter some time of nine days we find some red liquid in thebottle and collect it subsequently we measure the volume ofthe collected liquid and the measurement result is 158mL Inthe same way we change the commercial Nafion membrane

0 5 10 15 20

0

5

10

15

20

minusZ998400998400

(ohm

)

Z998400 (ohm)

Figure 3 The AC impedance diagram of the quaternized poly-sulfone membrane High freq (Hz) = 1e + 5 low freq (Hz) = 1amplitude (V) = 0005

instead of quaternized polysulfone composite membrane andrepeat the above steps and another measurement data of thecollected liquid is obtained namely 9mL

Compared with the two different measured volumes wefind that quaternized polysulfonemembrane ismore useful tolet the solution pass through it than the commercial Nafionmembrane So quaternized polysulfone membrane is moresuitable for zinc-bromine redox flow battery

35 Battery Performance Figure 4 shows polarization curvesof the battery with quaternized polysulfone membranes at


004 005 006 007 008 009 01017

18

19

20

21

22

23

24

25

26

Char

ge v

olta

ge (V

)

Charge current (A)

Figure 4 Polarization curves of the battery with quaternizedpolysulfone membranes at different charge voltage

01 02 03 04 0500

02

04

06

08

10

Disc

harg

e vol

tage

(V)

Discharge current (A)

Figure 5 Polarization curves of the battery with quaternizedpolysulfone membranes at different discharge voltage

different charge voltage Because the theoretical open circuitpotentials for the battery were 182V the present charge testwas carried out with a voltage slightly higher than 18 V Fromthe data we see that the battery performance increased withthe voltage increasing at the same temperature and pressure

This indicates that there was still a small degree ofporosity in the membrane This factor would need to beinvestigated in more detail in subsequent development of themembrane for redox flow battery applications

Figure 5 shows polarization curves of the battery withquaternized polysulfone at different discharge voltage Asexpected battery voltage declined with current densityincreasing while discharging For example at a cell currentof 01 A the discharge voltage was 09672V and the powerdensity was 6mWcm2 while at 015 A current the voltagewas 04724V and the power density was 44mWcm2 Therelatively good performance was mainly attributed to thehigh proton conductivity of the composite membrane Themajor cause for voltage loss of the battery was associated withthe performance of the electrode layers and solution This

indicates that the improvement of the zinc-bromine batteryperformance can be made through further development ofthe electrodes and solution

4 Conclusions

A quaternized polysulfone (QNPSU) composite membranehas been fabricated for zinc-bromine redox flow battery Thestructure of the membrane is examined by FT-IR spectra andSEM The successful synthesis of membrane was compara-tively dense and no holes were produced Tested by electro-chemical analyzer the conductivity of themembrane is about001 Scm in 25∘C with 100 RH A zinc-bromine batterywith this compositemembrane is operated at different voltagewhile charging and at different current while dischargingThe battery performance of the membrane shows that thedischarge voltage was 09672V and the power density was6mWcm2 at a 01 A current This result indicates that thenovel composite membrane is a promising material for theflow battery

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgment

This work was supported by the Fundamental ResearchFunds for the Central Universities

References

[1] P Singh and B Jonshagen ldquoZincbromine battery for energystoragerdquo Journal of Power Sources vol 35 no 4 pp 405ndash4101991

[2] E D Woumfo and O Vittori ldquoElectrochemical behaviour ofa zinc electrode in 8M KOH under pulsed potential loadingrdquoJournal of Applied Electrochemistry vol 21 no 1 pp 77ndash83 1991

[3] P Singh KWhite andA J Parker ldquoApplication of non-aqueoussolvents to batteries part I Physicochemical properties of pro-pionitrilewater two-phase solvent relevant to zinc-brominerdquoJournal of Power Sources vol 10 no 4 pp 309ndash318 1983

[4] G Bauer J Drobits C Fabian H Mikosch and P SchusterldquoRaman spectroscopic study of the bromine storing complexphase in a zinc-flow batteryrdquo Journal of Electroanalytical Chem-istry vol 427 no 1-2 pp 123ndash128 1997

[5] Y Ito M Nyce R Plivelich M Klein D Steingart andS Banerjee ldquoZinc morphology in zinc-nickel flow assistedbatteries and impact on performancerdquo Journal of Power Sourcesvol 196 no 4 pp 2340ndash2345 2011

[6] M Mastragostino and S Valcher ldquoPolymeric salt as brominecomplexing agent in a Zn-Br

2model batteryrdquo Electrochimica

Acta vol 28 no 4 pp 501ndash505 1983[7] D J Eustace ldquoBromine complexation in zinc-bromine circulat-

ing batteriesrdquo Journal of the Electrochemical Society vol 127 no3 pp 528ndash532 1980

[8] K Scott W M Taama and P Argyropoulos ldquoPerformance ofthe direct methanol fuel cell with radiation-grafted polymer


membranesrdquo Journal of Membrane Science vol 171 no 1 pp119ndash130 2000

[9] S Lu J Pan A Huang L Zhuang and J Lu ldquoAlkaline polymerelectrolyte fuel cells completely free from noble metal catalystsrdquoProceedings of the National Academy of Sciences of the UnitedStates of America vol 105 no 52 pp 20611ndash20614 2008

[10] M Li L Yang S Fang and S Dong ldquoNovel polymeric ionicliquid membranes as solid polymer electrolytes with high ionicconductivity at moderate temperaturerdquo Journal of MembraneScience vol 366 no 1-2 pp 245ndash250 2011

[11] J R Varcoe and R C T Slade ldquoProspects for alkaline anion-exchange membranes in low temperature fuel cellsrdquo Fuel Cellsvol 5 no 2 pp 187ndash200 2005

[12] J R Varcoe and R C T Slade ldquoAn electron-beam-grafted ETFEalkaline anion-exchange membrane in metal-cation-free solid-state alkaline fuel cellsrdquo Electrochemistry Communications vol8 no 5 pp 839ndash843 2006

[13] A Warshawsky and O Kedem ldquoPolysulfone-based interpoly-mer anion exchange membranerdquo Journal of Membrane Sciencevol 53 no 1-2 pp 37ndash44 1990

[14] W Kautek A Conradi C Fabjan and G Bauer ldquoIn situ FTIRspectroscopy of the Zn-Br battery bromine storage complex atglassy carbon electrodesrdquo Electrochimica Acta vol 47 no 5 pp815ndash823 2001

[15] D Ayme-Perrot S Walter Z Gabelica and S Valange ldquoEvalu-ation of carbon cryogels used as cathodes for non-flowing zinc-bromine storage cellsrdquo Journal of Power Sources vol 175 no 1pp 644ndash650 2008

[16] S L Chiu and J R Selman ldquoDetermination of electrodekinetics by corrosion potential measurements zinc corrosionby brominerdquo Journal of Applied Electrochemistry vol 22 no 1pp 28ndash37 1992

[17] P M Hoobin K J Cathro and J O Niere ldquoStability ofzincbromine battery electrolytesrdquo Journal of Applied Electro-chemistry vol 19 no 6 pp 943ndash945 1989

[18] B P Tripathi M Kumar and V K Shahi ldquoOrganic-inorganichybrid alkaline membranes by epoxide ring opening for directmethanol fuel cell applicationsrdquo Journal of Membrane Sciencevol 360 no 1-2 pp 90ndash101 2010

[19] J Fang and P K Shen ldquoQuaternized poly(phthalazinon ethersulfone ketone) membrane for anion exchange membrane fuelcellsrdquo Journal ofMembrane Science vol 285 no 1-2 pp 317ndash3222006

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


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Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


(Catalyst)

CH3 CH3

O

SOO

O

O

SOO

O

ZnCl2ClCH2OCH2CH3

CH2Cl CH2Cl

CH3 CH3

Scheme 1 Preparation of the chloromethylation of polysulfone

added dropwise into the reaction kettle and the reactionproceeded for 8 h at 70∘C The final reaction solution waslight red The white product was precipitated in hot waterThe resulted step was dried in high vacuum to remove anyresidual solvent and kept in a vacuum before further use

The preparation of the chloromethylation of polysulfoneis as shown in Scheme 1

23 Preparation of CMPFSCompositeMembrane 5 gCMPFSwas dissolved in 30 cm3 (mL) N-methyl-2-pyrrolidone(NMP) and then the mixture was stirred at 60∘C Compositemembranes of CMPFS were prepared by CMPFS-NMPsolution evenly spreading on the glass for 30min at 60∘C andthen dried at 100∘C

24 Preparation of the Quaternized Polysulfone MembraneTheprocedure for the preparation of the quaternized polysul-fone membrane was as followsThe composite membranes ofCMPFSwere bathed in 100 cm3 (mL) trimethylamine (TMA)till the membranes softened Then the membrane was rinsedwith copious amounts of deionised (DI) water immersed inaqueous NaOH (10moldm3) solution for 12 h at 25∘C andthen dried

The preparation of the quaternized polysulfone mem-brane is as shown in Scheme 2

25 ConductivityMeasurement Membrane conductivity wasmeasured with a four-point probe and frequency responseelectrochemical analyzer CHI604D (Shanghai ChenhuaInstrument Co Ltd) The polymer membranes were held atthe desired temperature and humidity for 05 h to ensure thata steady state was achieved and measurements were taken at1min intervals

26 Battery Tests Themembranes were cut into 4 cm times 4 cmHigh-density graphite plates are used directly as frameworkcomponents and electrodesThere is a 5mmdepth slot on oneside of graphite plates to make solution circulate smoothly

CH3 CH3

CH3 CH3

O

SOO

O

O

SOO

O

N(CH3)3

CH2Cl CH2Cl

CH3N(CH3)3Clminusminus++

(CH3 )3NCH3Cl

Scheme 2 The preparation of the quaternized polysulfone mem-brane

500 1000 1500 2000 2500 3000 3500 40000

20

40

60

80

100

Tran

smitt

ance

() 3380

2970

1220

1325

Wavenumbers (cmminus1)

Figure 1 FT-IR spectra of quaternized polysulfone membrane

Themolarities of zinc-bromine solution are about 4molL sothat the amount is nearly half of the optimal value not only forthe conductivity but also for the bromine solubility [14ndash17]The anode and cathode electrodes were filled with electrolytethrough constant pumping

This research carried out the battery charging and dis-charging tests through battery testing system 75X (NewareCo Ltd)The charge was conducted by a designated currentwhile the discharge was at a constant current

3 Results and Discussion

31 FT-IR Analysis Figure 1 shows the infrared spectra ofquaternized polysulfone membrane We can find that S=Ovibration peaks are at 1220 and 1325 cmminus1 [18] The broadpeak at around 3380 cmminus1 was attributed byOndashHand residualwaterThe quaternary ammonium group stretching vibrationpeaks are at 2970 cmminus1 [19] The data suggests that there wasa successful synthesis of quaternized polysulfone compositemembrane


(a) (b)

(c)







0 5 10 15 20

0

5

10

15

20

minusZ998400998400

(ohm

)

Z998400 (ohm)






004 005 006 007 008 009 01017

18

19

20

21

22

23

24

25

26

Char

ge v

olta

ge (V

)

Charge current (A)


01 02 03 04 0500

02

04

06

08

10

Disc

harg

e vol

tage

(V)







4 Conclusions




Acknowledgment


References

































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


(a) (b)

(c)







0 5 10 15 20

0

5

10

15

20

minusZ998400998400

(ohm

)

Z998400 (ohm)






004 005 006 007 008 009 01017

18

19

20

21

22

23

24

25

26

Char

ge v

olta

ge (V

)

Charge current (A)


01 02 03 04 0500

02

04

06

08

10

Disc

harg

e vol

tage

(V)







4 Conclusions




Acknowledgment


References

































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


004 005 006 007 008 009 01017

18

19

20

21

22

23

24

25

26

Char

ge v

olta

ge (V

)

Charge current (A)


01 02 03 04 0500

02

04

06

08

10

Disc

harg

e vol

tage

(V)







4 Conclusions




Acknowledgment


References

































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of























Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article a quaternized polysulfone membrane for...

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