atomic layer deposition of zirconium oxide for fuel cell applications uic reu – summer 2011 amrel...

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Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department of Chemical Engineering Christine James University of Michigan, Department of Chemical Engineering

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Page 1: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications

UIC REU – Summer 2011AMReL Lab, UIC

Department of Bioengineering andDepartment of Chemical Engineering

Christine JamesUniversity of Michigan, Department of Chemical Engineering

Page 2: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Overview

• Background• Atomic Layer Deposition• Data Collected• Future Work

Page 3: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Fuel Cell Advantages

• Provides clean energy– Hydrogen fuel cells – only emit water

• Very efficient– Fuel Values

• Hydrogen: 141.8 kJ/g• Gasoline: 48 kJ/g • Coal: 15-27 kJ/g

Santhanam et al., Introduction to Hydrogen Technology, 2009, Hoboken, NJ: J. Wiley.

Fossil fuel

2007

Environmentally friendly

Coal 23 %

Nuclear Power 8 %

Renewable Energy 6 %

Petroleum 40 %

Natural Gas 23 %

Source: US Energy Information Agency

Page 4: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Sections of the Fuel Cell

• Cathode– Oxygen is reduced

• Anode– Hydrogen is oxidized

• Electrolyte– Transports the oxygen ions

www1.eere.energy.gov

SOFC FUEL CELL

Fuel In Air In

Unused Gases Out

Excess Fuel and

Water

Electrical Current

Page 5: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Solid Oxide Fuel Cells (SOFCs)• Current SOFCs are high temperature– Temperature: about 1000 °C

• Intermediate Temperature Fuel Cells– Temperature: 600-800°C– Smaller scale applications– Allows use of alternate materials– Starts and stops faster– Reduces corrosion – Offers a wide range of possibilities

Page 6: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Problem with Reducing Temperature• High temperatures needed to transport O2- ions – Requirement can be as high as 1200° C– Low temperatures cause ionic resistance

• Deposit electrolytes and analyze– Samples from atomic to bulk-like thickness– Method to be used:

• Atomic Layer Deposition

• Deposit oxide layers on silicon then platinum (Pt)

Approach

Page 7: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Atomic Layer Deposition (ALD)

www.cambridgenanotech.com/ald

H2O

Tri-methyl aluminumAl(CH3)3(g)

Methyl group(CH3)3(g)

Hydroxyl (OH) from surface absorbed H2O

Reaction of TMA with OH

Methane reaction product CH4

Page 8: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Chosen Precursor

www.aloha.airliquide.com

Niinistö, et al., Advanced Engineering Materials, 2009, 11, No.4, 223.

Precursors   Growth Temperature   ImpuritiesMetal Precursor O source   Range (°C) Preferred (°C) Saturation verified   C [-at%] H [-at%]

          at 300 °C      ZyALD Ozone   250-400 300 Yes   <1 N.R.

Page 9: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

ALD System

ZyALD

ZyALD

Page 10: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Pulse and Purge times requiredReactor Temperature: 300°CBubbler Temperature: 50°CBubbler Pressure: 10 torrPrecursor: ZyALDPrecursor Pulse Time:

Precursor Purge Time:Oxidizer Pulse Time:Oxidizer Purge Time:Run for 40 cycles

Varied6 s

20 sVaried1.5 s

Varied

2 2.5 3 3.5 4 4.5 5 5.5 6 6.50.4

0.5

0.6

0.7

0.8

0.9

1

Precursor Pulse Time (s)

Gro

wth

Rat

e (Å

/cyc

le)

2 4 6 8 10 12 140.700000000000001

0.750000000000001

0.800000000000001

0.850000000000001

0.900000000000001

0.950000000000001

1

Precursor Purge Time (s)

Grow

th R

ate

(Å/c

ycle

)

10 s

0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.80.600000000000001

0.650000000000001

0.700000000000001

0.750000000000001

0.800000000000001

0.850000000000001

0.900000000000001

0.950000000000001

1

Oxidizer Pulse Time (s)

Gro

wth

Rat

e (Å

/cyc

le)

12 13 14 15 16 17 180.600000000000001

0.650000000000001

0.700000000000001

0.750000000000001

0.800000000000001

0.850000000000001

0.900000000000001

0.950000000000001

1

Oxidizer Purge Time (s)

Gro

wth

Rat

e (Å

/cyc

le)

17 s

1 s

Varied

Zr

www.cambridgenanotech.com/ald

Page 11: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Temperature WindowReactor Temperature: VariedBubbler Temperature: 50°C

Bubbler Pressure: 10 torrPrecursor: ZyALD

50 100 150 200 250 300 350 4000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Temperature (°C)

Gro

wth

Rat

e (Å

/cyc

le)

Precursor Condensation Precursor Decomposition

Temperature Window

Page 12: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Comparison to Work from another group

225 250 275 300 325 3500

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Temperature (°C)

Gro

wth

Rat

e (Å

/cyc

le)

Niinistö, et al., J. Mater. Chem. 18, 5243 (2008).

Page 13: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Thickness vs. Cycles RunReactor Temperature: 300°CBubbler Temperature: 50°C

Bubbler Pressure: 10 torrPrecursor: ZyALD

0 20 40 60 80 100 120 140 160 1800

20

40

60

80

100

120

140

160

Number of Cycles Run

Thic

knes

s (Å

) Slope: .87R² = 0.9973

Page 14: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Future Work

1. Deposit the zirconium oxide on Platinum2. Run electrochemical analysis

Silicon Substrate

Electrolyte: Zirconium Oxide

Platinum

Page 15: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Summary• Goal is to lower operating temperature of the fuel cell– By decreasing electrolyte layer thickness

• Atomic Layer Deposition (ALD) is being used• Have determined some necessary parameters:– Pulse and Purge times– Temperature Window for ALD

• Have compared cycles and thickness– Proved linear relationship

• Next Steps: – Deposit on Platinum – Run Electrochemical analysis

Page 16: Atomic Layer Deposition of Zirconium Oxide for Fuel Cell Applications UIC REU – Summer 2011 AMReL Lab, UIC Department of Bioengineering and Department

Acknowledgements

• National Science Foundation– EEC-NSF Grant # 1062943

• Graduate Mentor: Runshen Xu• Professor Takoudis and Professor Jursich