May 8 AMFC Workshop - US Department of Energy May 8 th 2011 AMFC Workshop AM FC Performance with...

May 8th 2011 AMFC Workshop

2011 AMFC WORKSHOP2011 AMFC WORKSHOP

Electrolyte Materials for AMFCsElectrolyte Materials for AMFCs and AMFC Performanceand AMFC Performance

May 8May 8thth 20112011 Tokuyama CorporationTokuyama Corporation

Kenji FukutaKenji Fukuta

Tokuyama Research LaboratoryRC Research Laboratory

Tokuyama Factory

Tsukuba Research Laboratory

Tokyo Head Office

Ｎ

Ｓ

ＥＷ

Total area 1,910,000 m2

280,000 m2

610,000 m2

Tokuyama Station

1,020,000 m21,020,000 m2

Higashi Plant (organic, electronics)

Policlystalline Silicon Inorganics

Organics & Polymers


LLooccaattiioonn ooff TTookkuuyyaammaa CCoorrppoorraattiioonn Total area 1,910,000 m2

Public Wharf

Nanyo Plant (cement)Undersea tunnel

Tokuyama Plant (inorganic)

280,000 m2

610,000 m2

July 28th 2009

GRC -FCs

AApppplliiccaattiioonn ooff HHyyddrrooccaarrbboonn IIEEMM

エレクトロ二クスElectronics

食品・医薬Food And Pharmaceutical

* Production of High Purity Chemicals * Production of Ultra Pure Water * Battery Diaphragm

* Demineralization of Cheese Whey

and Amino Acids * Desalination of Soy-Sauce * Stabilization of Wine * Demineralization and Purification of Pharmaceutical Intermediate

その他

Ion exchange Membrane NEOSEPTAIon exchange Membrane NEOSEPTA ®®

* Production of Salt from Sea water * Production of Drinking Water from Brackish Water

* Desalination of Deep Sea Water * Acid Recovery from Waste Acid

* Demineralization of Organic Acids

Environmental Conservation

Others

NEOSEPTANEOSEPTA®®

EDCOREEDCORE

NEOSEPTANEOSEPTA®®BIPOLARBIPOLAR

ACILYZERACILYZER

* Desalination of Leachate * Removal of Nitrate from Under-Ground Water

EElleeccttrrooddiiaallyyzzeerrss AACCIILLYYZZEERR

July 28th 2009 GRC -FCs

OOuuttlliinnee

１１．．TTookkuuyyaammaa’’ss EElleeccttrroollyyttee MMaatteerriiaallss ffoorr AAMMFFCCss・・AAnniioonn eexxcchhaannggee mmeemmbbrraannee・・AAllkkaalliinnee IIoonnoommeerr２２．．PPeerrffoorrmmaannccee ooff AAMMFFCCss・・PPoowweerr ddeennssiittyy・・CChhaarraacctteerriissttiicc bbeehhaavviioorr iinn AAMMFFCC

CCOO22 pprroobblleemm WWaatteerr ttrraannssppoorrtt

・・DDuurraabbiilliittyy３３．．SSuummmmaarryy

N +

OHN +

N +

OHN +

N +

N +

OH

OH OH

N +

N +

N +

OHOH

OHOH

N +

OHN +

N +

OHN +

N +

N +

OH

OH OH

N +

N +

N +

OHOH

OHOH

May 8th 2011

AMFC Workshop

TTookkuuyyaammaa AAnniioonn eexxcchhaannggee MMeemmbbrraannee

Structural image

-

--

-

- -

- --

-

--

-

- -

- --


PPrrooppeerrttiieess ooff AAnniioonn EExxcchhaannggee MMeemmbbrraanneess

Properties A201

（Tokuyama）

A901（Tokuyama）

Fluorinated membrane

（Cation Membrane）

Thickness ／μm 28 10 180 Ion-exchange capacity ／mmol･g-1 1.8 1.8 1.0

Water content ／－ 0.25 0.15 0.30 Ion conductance 1）／mS･cm-2 11 29 4.2 Ion conductivity 1）／mS･cm-1 42 38 84 Burst strength ／MPa 0.4 0.2 0.5

Dimensional change MD TD

wet⇔dry／ %／ %

2 6

1 4

10 15

1) Two probe method for in plane conductivity measurement at 23 ℃, 90%RH under N2 atmosphere, at OH- form

300

May 8th 2011

AMFC Workshop

AAMMFFCC PPeerrffoorrmmaannccee wwiitthh DDiiffffeerreenntt MMeemmbbrraannee

Cel

l vol

tage

/ V

1.2

1

0.8

0.6

0.4

0.2

0 0

50

100

150

200

250

350

Pow

er d

ensi

ty /

mW･cm

-2

A901/10μm

A201/28μm

H2/clean air at 50 ℃ Pt/C catalyst

0 0.2 0.4 0.6 0.8 1 1.2 1.4

Current density / A･cm-2

【MEA composition】【measurement condition】 Membrane ：A201 or A901 Cell temp. ：50℃ Ionomer ：AS－4 Anode ：95%RH H2 0.5L/min（A201）、1.0L/min（A901） Pt amount ：0.5mg/cm2 Cathode ：95%RH clean air 1.0L/min（A201）、2.0L/min（A901）


SSttaabbiilliittyy TTeesstt ooff MMeemmbbrraannee ((AA220011))

Membrane was ion-exchanged to OH- form and stored in the air before durability test.

-(maybe converted to HCO3 form)

時間／hrs

イオン交

換容

量保

持率

／％


AAcccceelleerraatteedd DDuurraabbiilliittyy TTeesstt

New membrane

・A201 vs. New membrane・12wt%-EtOH + 20wt%-KOH・80℃

･different ion-exchange group

100 ～80℃

80

・A20160 ～70℃

40

20

0 0 500 1000 1500

Time / hrs

Rem

aine

d io

n ex

chan

ge g

roup

/ %

July 28th 2009 GRC -FCs

TTookkuuyyaammaa AAkkaalliinnee IIoonnoommeerrss

N+ OH

N+ OH

N+ OH

N+

OH

□ Structural image

□ Needs for ionomers

Linear hydrocarbon backbone with quaternary ammonium group

・High ion conductivity・Solubility into solvent at preparation of catalyst ink・Non-solubility after preparation of catalyst layer・Dispersivity in catalyst ink・Durability

etc.

11 July 28th 2009 GRC -FCs

PPrrooppeerrttiieess ooff AA--IIoonnoommeerr SSoolluuttiioonn

State Features A3 ver.2 AS-4

solution Polymer concentration／wt% Solvent

Ion-exchange capacity／mmol･g-1

5 Tetrahydrofuran

& 1-Propanol 0.7

5 1-Propanol

1.4

membrane (cast film)

Ion conductivity／mS･cm-1

(HCO3 - form)

Solubility to solvent Water MeOH EtOH

2.6

not soluble not soluble not soluble

13

not soluble not soluble not soluble

1)～3) Measured using cast film -2) Measured on alternative current(40℃, wet) ,at HCO3 form

CellP

oten

tial(V)

AAMMFFCC PPeerrffoorrmmaannccee - IIoonnoommeerr TTyyppee May 8th 2011

AMFC Workshop

1.2 120

1

AS-4使用MEAH2/air at 50℃ Pt/C catalyst

A3使用MEA

100

0.8 80 AS-4

0.6 max power： 95mW/cm2 60

0.4 40

Pow

erDen

sity

(mW/c

m2)

0.2 A3V2 20

0 max power：22mW/cm2

0

0 100 200 300 400 500 600

Current Density(mA/cm2)

【MEA composition】 Membrane ：A801 Ionomer ：AS-4 or A3 ver.2 Pt amount ：0.5mg/cm2

【measurement condition】 Cell temp. ：50℃ Anode ：95% RH H2 Cathode ：95% RH air


EEffffeecctt ooff iimmpprroovveedd iioonnoommeerr

Ionomer IEC (mmol/g) Conductivity (mS/cm) AS-4 1.4 14 AS-X 1.8 17

1.2 300

AS-4 (14mS/cm) AS-X (17mS/cm)

1 250

0.8 200

0.6 150

0.4 100

Pow

er d

ensi

ty /

mW・cm

-2

0.2 50

Volta

ge /

V

0 0 0 0.2 0.4 0.6 0.8 1 1.2

Current density / A・cm-2


OOuuttlliinnee





FFaabbrriiccaattiioonn ooff CCCCMM

◎ Fabrication process （ Catalyst ： Iononer = 7:3）

Catalyst （Pt/C） De-ionized Water

Weigh and mix

Iononer solution（5wt% - AS-4）

CCM

Agitation

viscosity control

Screen painting

Stir Catalyst ink

CCM (5cm2)


EEvvaalluuaattiioonn PPrroocceedduurree

□ Evaluation of I-V curves・GDL : Toray TGP-H060 (without hydrophobic treatment)・fuel : H2 (95%RH, 1000mL/min)・oxidant : clean-air (CO2<0.1ppm, 95%RH, 2000mL/min)

or O2 (95%RH, 1000mL/min)･Temperature : 50℃

・evaluation step : MEA set into cell → pre-operation at 0.1V for 15min (for activation)

→ measurement of I-V curves

□ Optimized condition･Pt/C:ionomer = 7:3 (in case of Pt/C(Pt;46wt%), at high flow rate)･Maybe differ by catalyst and flow condition


EEffffeecctt ooff PPrree--AAccttiivvaattiioonn

-HCO3 form membrane changes to OH- form by the OH- generated at cathode through pre-operation (self-purging), and it makes the performance higher.

1.2

1

0.8

0.6

0.4

0.2

0

Cel

l vol

tage

/ V

1st scan (without pre-operation)

3rd scan

After pre-operation (0.1V-15min)

0 100 200 300 400 500 600 Current density / mA･cm-2


IInnfflluueennccee ooff IIoonnoommeerr CCoonntteenntt

Pt/C:AS-4 = 7:3 shows the best performance in this condition. Appropriate content should be differed by catalyst and operation condition.

1.2 300 Pt : 0.4mg/cm2

H2:500ml/min1 Clean-air:1000ml/min 250

Pow

er d

ensi

ty /

mW･

cm-2

Volta

ge /

V

0.8 200 Pt/C:AS-4 = 7:30.6 150

0.4 100 = 8:2

0.2 50 = 6:4 0 0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Current density / A･cm-2

200

400

mW


OOppttiimmiizzeedd PPeerrffoorrmmaannccee aatt TTookkuuyyaammaa

Menbrane:A201 → A901, Ionomer:AS-4 → AS-X, Pt/C:AS-X=7/3, 0.5mg-Pt/cm2

Cel

l vol

tage

/ V

1.2

1

0.8

0.6

0.4

0.2

0 0

100

300

500

600

Pow

er d

ensi

ty /

･ cm

-2

A201 → A901

Clean air → O2

450mW/cm2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Current density / A･cm-2

Best power density : 340mW/cm2 (using clean air) 450mW/cm2 (using O2)


AMFC Performance（MeOH/KOH-Air）

1 250

0.8 200

Pow

er density／mW･cm

-2

・Membrane ： A201・Catalyst ： Anode Pt-Ru/C

1.1mg/cm2

Cathode Pt/C 0.5mg/cm2

・Ionomer ： AS-4・Fuel ： 3wt%-MeOH

+ 5wt%-KOH 10ml/min

・Oxidant ： 95%RH Clean Air 4000ml/min

・Temp. ： 80℃

Voltage／V

0.6 150

0.4 100

0.2 50

0 0 0 300 600 900 1200 1500

Current density／mA・cm -2


OOuuttlliinnee




May 8th 011222

AMFC Workshop

CCOO22 AAbbssoorrppttiioonn iinnttoo AAllkkaalliinnee MMeemmbbrraannee --OOHH-- iiss cchhaannggeedd ttoo CCOO33

22-- iinn aa ffeeww mmiinnuutteess,, ffuurrtthheerr ttoo HHCCOO33 ..

NNeeeeddss ttoo kknnooww tthhee eeffffeecctt ooff ccoouunntteerr iioonn oonn tthhee ccoonndduuccttiivviittyy

1.6

1.4

1.2

1

0.8

0.6

0.4

0.2

0

OH-

CO3=

HCO3-

0 20 40 60 80 100 120 140

time/min Membrane:A201

ion conc./

mmol・g -

1


EEffffeecctt ooff tthhee ccoouunntteerr aanniioonn

MMeemmbbrraannee CCoonndduuccttiivviittyy ddeeppeennddss oonn tthhee mmoobbiilliittyy ooff ccoouunntteerr aanniioonn ..

110000

8800

6600

4400

2200

00

IIoonn ccoonndd

uuccttiivviittyy

((@@4400℃℃）） //

mmSS・・ccmm

--11

OH-

HCO3- Cl-

A201 membranemeasured @ 40℃

OH

HCO3 - Cl

A201 membrane measured @ 40℃

00 5500 110000 115500 220000 225500

LLiimmiittiinngg mmoollaarr ccoonndduuccttiivviittyy // SS・・ccmm 22・・mmooll--11


SSeellff--PPuurrggiinngg ((IInniittiiaall SSttaaggee))

ｅ－

H2 + 2OH

AEM Ionomer

HCO3 -

HCO3 -

HCO3 -

HCO3 -

HCO3 -

HCO3 HCO3 -

HCO3 -

HCO3 -

HCO3 -

HCO3 -

-

HCO3 -

HCO3 -

HCO3 -

HCO3 -

1/2O2 + H2O + 2e→ 2H2O + 2e

→ 2OH

lower pH higher pH

-HCO3 -OH- + HCO3→ OH- + CO2↑ → CO32- + H2O

self-purge : J.Varcoe et. al, ChemSusChem 2008, 1, 79–81


SSeellff--PPuurrggiinngg ((SStteeaaddyy SSttaattee))

ｅ－

H2 + 2OHOH-

OH-

OH-

CO3 2-

OH-

AEM

OH-

OH-

OH-

CO3 2-

OH-

1/2O2 + H2O + 2e→ 2H2O + 2e

Ionomer

OH-

OH-

OH-

CO3 2-

OH-

→ 2OH

lower pH

CO32- + H+

-→HCO3 CO2 → OH- + CO2↑

H2

e ＋－

H2 100ml/min 95%RH

Cell Temp.：50℃

OHH2 + 2OH→ 2H2O + 2e

MS


iinn--ssiittuu AAnnaallyyssiiss ooff CCOO22

Clean

Air 200ml/min 95%RH

Air

1/2O2 + H2O + 2e- → 2OH

in-situ CO2 measurement


OObbsseerrvvaattiioonn ooff CCOO 22 RReelleeaassee ffrroomm AAnnooddee

8000 0 .6

・A201、AS-4、Pt/C7000

0 .5・H2/clean air、50℃CO

2/ppm

6 0 0 0

0 .4 5 0 0 0

4 0 0 0 0 .3

3 0 0 0 0 .2

2 0 0 0

0 .1 1 0 0 0

0 0 2 5 0 0 3 5 0 0 4 5 0 0 5 5 0 0 6 5 0 0

T im e / s e c

currentdensity/A･c

m -2

CO2 is released quickly after increasing current density. Released amount seems to depend on the current density.

⇒ Ref. Z. Siroma,et. al., J. ElectroChem. Soc., 158, B682 (2011).


MMooddeelliinngg ooff CCOO22 ccoonncceennttrraattiioonn pprrooffiillee

equivalent ratio, X Assumption

electric field ・flux of carbonate ion is zero 1 throughout the membraneX0

･concentration of OH- at the end of anode is fixed to zero

XL position, x

0 L anode cathode

OH

A-

diffusion

migration

migration diffusion

COH/C0

CA/C0

membrane

Z. Siroma,et. al., J. ElectroChem. Soc., 158, B682 (2011).


Calculated COCalculated CO22 concentration profileconcentration profile

0

0.2

0.4

0.6

0.8

1

equi

vale

nt ra

tio o

f the

obs

truct

ing

ion

(loca

l)

0.2 A/cm2

0.4 A/cm2

0.6 A/cm2

0.8 A/cm2

--- for HCO3 -

for CO3 2

Released amount of CO2 after step from

0.2 to 0.4A/cm2

0 5 10 15 20 25

(anode side) position / Pm (cathode side)


OOuuttlliinnee





WWaatteerr TTrraannssppoorrtt MMeeaassuurreemmeenntt

9 To learn how the water for ORR is supplied in AMFC 9 To test the operation under the dry gas feeding condition

Humidified H2 Humidified O2

Anode Cathode

producedinouttransport nnnn ��

Net Water Flux from anode to cathode; transportn

outn

inn

transportnproducedn

The Conditions for humidification in this study

Anode (H2) Cathode (O2)

100 100

100 0 (dry gas)

0 (dry gas) 0(dry gas)

DRIERITE within bottleDRIERITE within bottle

Exhausted gasExhausted gas from the cellfrom the cell

From the presentation at 219th ECS meeting (Montreal)

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200

Current Density /mAcm 2

Cel

l Vol

tage

/V

Anode 100%RH Cathode 100%RH

Anode 100%RH Cathode Dry

Anode Dry Cathode Dry

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200

Current Density /mAcm 2

Cel

l Vol

tage

/V


AAMMFFCC PPeerrffoorrmmaannccee wwiitthh DDrryy FFeeeedd CCoonnddiittiioonnss

9 AMFC performance decreased with lowered humidity. 9 The effect of cathode humidity was quite small.

0

0.2

0.4

0.6

0.8

1

1.2

Cel

l Vol

tage

/V Anode 100%RH

Cathode 100%RH


Anode Dry Cathode Dry

0 200 400 600 800 1000 1200

Current Density /mAcm ---2

FFFiiiggg...111 PPPooolllaaarrriiizzzaaatttiiiooonnn CCCuuurrrvvveeesss uuunnndddeeerrr vvvaaarrriiiooouuusss hhhuuummmiiidddiiifffiiieeeddd cccooonnndddiiitttiiiooonnnsss AAAnnnooodddeee fffeeeeeeddd::: HHH222 222000000mmmLLLmmmiiinnn---111,,, CCCaaattthhhooodddeee fffeeeeeeddd::: OOO222 222000000mmmLLLmmmiiinnn---111 CCCeeellllll TTTeeemmmpppeeerrraaatttuuurrreee 555000oooCCC

T. Isomura et.al., Abstract of 219th ECS meeting, #221(2011)


NNeett WWaatteerr FFlluuxx ffrroomm AAnnooddee ttoo CCaatthhooddee

9 At 100%RH/100%RH, net water flux from anode to cathode was same as the theoretical amount of water required for ORR.

9 It suggested that all the water required for ORR was supplied from anode.

0

2

4

6

8

10N

etW

ater

Flux

/mg

cm-2

min

-1

Anode 100%RHCathode 100%RH

Anode 100%RHCathode Dry

Calculated Value for ORR

0

2

4

6

8

10N

etW

ater

Flux

/mg

cm-2

min

-1

0

2

4

6

8

10 N

et W

ater

Flu

x /m

g cm

-2 m

in-1

Anode 100%RH Cathode 100%RH


Calculated Value for ORR

000 222000000 444000000 666000000 888000000 111000000000 111222000000

CCCuuurrrrrreeennnttt DDDeeennnsss iiitttyyy ///mmmAAAcccmmm ---222

FFFiiiggg...222 NNNeeettt WWWaaattteeerrr FFFllluuuxxx fffrrrooommm aaannnooodddeee tttooo cccaaattthhhooodddeee uuunnndddeeerrr vvvaaarrriiiooouuusss hhhuuummmiiidddiiifffiiieeeddd cccooonnndddiiitttiiiooonnnsss DDDoootttttteeeddd llliiinnneee ssshhhooowwwsss cccaaalllcccuuulllaaattteeeddd aaammmooouuunnnttt ooofff wwwaaattteeerrr fffooorrr OOORRRRRR aaattt cccaaattthhhooodddeee,,, AAAnnnooodddeee fffeeeeeeddd::: HHH222 222000000mmmLLLmmmiiinnn---111,,, CCCaaattthhhooodddeee fffeeeeeeddd::: OOO222 222000000mmmLLLmmmiiinnn---111

CCCeeellllll TTTeeemmmpppeeerrraaatttuuurrreee 555000oooCCC

T. Isomura et.al., Abstract of 219th ECS meeting, #221(2011)


OOuuttlliinnee





DDuurraabbiilliittyy TTeesstt

□ With improved adhesion between membrane and catalyst layer, higher Pt loading seems to lead to better durability.

□ Even after long-term operation, IEC of membrane has not changed. 1 - 160

50℃, 100mA/cm2 constant current

-

-

-

-

-

- 140 0.8

- 120

- 1000.6

Res

ista

nce

/ mΩ

Vol

tage

/ V

80

60

40

0.4

0.2

0

20

0

0 100 200 300 400 500 600 700 800

Time / hr 【MEA composition】【measurement condition】 Membrane ：A201 Cell temp. ：50℃ Ionomer ：AS－4 Anode ：95%RH H2 100ml/min Pt amount ：0.8mg/cm2 Cathode ：95%RH clean air 200ml/min（A201）

PSU GDE (V) AS 4 (V)PSU GDE (Ω) AS 4 (Ω)


IImmpprroovveedd DDuurraabbiilliittyy wwiitthh CCrroossss--LLiinnkkeedd IIoonnoommeerr

□ With cross-linked Ionomer, which also has higher IEC, shows better durability.

0

10

20

30

40

50

60

70

80

90

100

0

0.2

0.4

0.6

0.8

1

1.2

0 1200 2400 3600 4800 6000

--

Volta

ge /

V

Res

ista

nce

/ mΩ

50℃, 100mA/cm2 constant current

Time / h


SSuummmmaarryy

□ By improving properties of electrolyte materials, optimizing MEA construction and operating conditions, maximum power density was increased.

・around 500mW/cm2 (H2/O2)･around 350mW/cm2 (H2/clean air)

□ CO2 in the air has large influence on the AMFC performance. To decrease the influence, AMFC operation at elevated temperature is effective, though it needs improved ionomer like cross-linked one.

・around 300mW/cm2 (at 80℃, H2/normal air) ・・・not shown, unpublished date of PSU

□ Durability at sate of the art・700hrs at standard materials・with cross-linked GDE : ＞4000hrs (50℃)

＞1200hrs (80℃) ・・・not shown, unpublished date of PSU

IIssssuueess ffoorr bbeetttteerr ppeerrffoorrmmaannccee □ Materials improvement : ion conductivity, thermal stability □ Decrease CO2 influence : new concepts other than high temp. operation □ MEA fabrication in relation with operating conditions


TThhaannkk yyoouu！！

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