Akshaya Jena and Krishna Gupta

Porous Materials, Inc.NY, USA

Fuel Cells R&DEnhancing Performance through Pore

Structure

Dependence of Performance of Fuel Cells on Pore Structure of its Components

Many fuel cell porous components Examples: Membranes, GDLs, Separators, Electrodes

Pore structure governs fluid flowPore structure influences kinetics of physico-

chemical processes occurring in fuel cellsPore structure characteristics are critical

factors that determine performance of fuel cells

Dependence of Performance of Fuel Cells

on Pore Structure of its Components

Important and relevant pore structure characteristics, which need to be determined: Pore diameter Pore throat diameter Pore volume Pore distribution Graded pore structure Surface area External surface area Total porosity Hydrophobic and hydrophilic nature of pores in a

mixture Liquid and gas permeability Diffusional flow

Influence of working environment on pore structure needs to be determined Chemical environment Operating temperature Humidity Stress generated during operation

Dependence of Performance of Fuel Cells

on Pore Structure of its Components

Many techniques are available for evaluation of pore structure characteristics of fuel cell components:

Capillary Flow Porometry Measures:

Wide range of through pore throat diameters Pore distribution Gas permeability Structure over a range of:

Temperature Stress Chemical environment Controlled humidity

Techniques for Measurement of Pore Structure Characteristics

Techniques for Measurement of Pore Structure Characteristics

Liquid Extrusion Porosimetry Measures:

Through pore volume Through pore diameters Pore distribution Hydrophobic pores Hydrophilic pores Structure over a range of:

TemperatureStressChemical environmentControlled humidity

Capillary Condensation Flow Porometry Measures:

Through nanopore diameter Distribution Flow rate Without structural distortion (Negligible pressure, Ambient

temperature)Permeametry

Measures: Gas, vapor, and liquid transmission rates Many chemical species Over a wide range of temperature, pressure, and

concentration

Techniques for Measurement of Pore Structure Characteristics

Vacuapore Measures:

Through and blind hydrophobic pore volume Pore diameter Pore distribution

Mercury Intrusion Porosimetry Measures:

Through and blind pore volume Pore diameter Pore distribution

Techniques for Measurement of Pore Structure Characteristics

BET Sorptometry Measures:

Surface area Very small through and blind pore volume Distribution Chemisorptions of many chemicals over a wide range of

temperature and pressure

Pycnometry Measures:

True and bulk density

Techniques for Measurement of Pore Structure Characteristics

About PMI Porous Materials, Inc. designs, manufactures, and

sells instruments for pore structure characterization Has vast experience in patenting of novel technology

for pore structure characterization and developing custom instruments for a wide variety of applications

Has published many papers and presented many oral and poster papers in conferences on pore structure, characterization of fuel cells, and battery components

Has supplied instruments to many fuel cell and battery related industries and research laboratories all over the globe

How Can PMI Help?

Pore Structure Characterization Instruments by PMI

PMI Fuel Cell Porometer

and Advanced Capillary Flow Porometer

Specially designed for fuel cell components

Other unique instruments

Liquid Extrusion Porosimeter

and Vacuapore

Pore Structure Characterization Instruments by PMI

Click here to download a full

PDF on this subject.

Pore Structure Characterization Instruments by PMI

The Capillary Condensation Flow Porometer

Specifically designed for

membranes with fine pores.

Pore Structure Characterization Instruments by PMI

All the instruments needed for pore

structure characterization of fuel

cell components are manufactured by PMI.

Fully automated: Test execution Data acquisition Data storage Data reduction

Windows-based menu driven simple operation

Objective, accurate, and reproducible results

The Fully Automated Instruments

PMI In-House Contract Testing Laboratory

We test fuel cell components of many customers from all over the globe.

Test time can be as low as two days.

What is Toray Paper? A carbon coated material extensively used in the fuel

cell industryVolume of Different Kinds of Pores

Different functions of fuel cell components are governed by different kinds of pores

PMI instruments used to measure pore volumes Volume of the through pores:

PMI Liquid Extrusion Porosimeter Volume of through and blind pores:

PMI Mercury Intrusion Porosimeter Volume of through and blind hydrophobic pores:

PMI Vacuapore

Example of Application of PMI Instruments:

Pore Structure Characterization of Toray Paper

Measured Pore Volume

Through Pores:

75% of the pore volume

Blind Pores:

25% of the pore volume

Hydrophobic Pores:

29% of pore volume

Hydrophilic Pores:

71% of pore volume Click here to download a full PDF on this subject.

Pore volume distribution given as distribution function

Differences between peaks used to estimate distribution of blind pores and hydrophilic pores

Pore Volume Distribution of Different Kinds of Pores

Pore Volume Distribution of Different

Kinds of Pores

Median pore diameters of various kinds of pores are shown in the table on the

following slide.Click here to download a PDF on the subject.

Characteristics

Through Pores

Blind Pores Hydrophobic Pores

Hydrophilic Pores

% of Pore Volume

75% 25% 29% 71%

Median Pore Diameter

60 m 40 m 35 m 50 m

Kind of Pore Hydrophilic

Hydrophobic

Blind Pores Through Pores

Median Pore Diameters of Various Pores

Through pores primarily hydrophilic

Blind pores primarily hydrophobic

Hydrophilic through pores also measurable by PMI Water Extrusion Porosimeter

Pore throat diameters determine Flow rate of fluid through the through pores Restrictions for passage of large particles through the

through pores Through pore throat diameters measurable by:

PMI Capillary Flow Porometer

Characteristics of Through Pores Responsible for Fluid Flow

Characteristics Values

The Largest Throat Diameter 50.43 m

Mean Flow Throat Diameter 32.48 m

Range of Throat Diameters 20 – 45 m

Change of Pore Diameter Along Pore Length

Small

Median Pore Diameter based on Volume

60 m

Volume of Pores 75%

Nature of Pores Hydrophilic

Pore Throat Characteristics of Through Pores

Distribution of Pore Throat Diameters

Most of the through pore throat diameters are in the range of 20-45 m

Comparison of Pore Throat Diameters and Volume Based Pore

Diameters

Comparison with volume based values suggests that shapes of through pores are not like hour glasses

Through pore diameters do not change appreciably along the pore length and are similar in magnitude

Click here to download a PDF on the subject.

You can visit our website to see the wide spectrum of pore structure capability that our instruments offer

If you have a special need that is not part of PMI’s standard test list, the engineers at PMI will be happy to talk to you about your testing requirements and come up with a suitable solution.

Special Needs

Have a nice day!

Thank you!