The document discusses a fuel cell characterization system from LXinstruments that uses Agilent Technologies equipment. The system allows for multi-channel electrochemical impedance spectroscopy (EIS) measurements of fuel cells in both stacked and segmented configurations. It utilizes an Agilent L4534A digitizer with four channels for measurements and Agilent electronic loads modulated by a function generator to provide variable load conditions. Proprietary software implements a lock-in amplifier algorithm to accurately measure frequency and phase responses from individual fuel cells. The system provides an affordable solution for comprehensive fuel cell testing and analysis.

1. Fuel Cell Characterization
Agilent Technologies and LXinstruments
Modular, multi-channel characterization of stacked
and segmented fuel cells Electrochemical
Research into the development of fuel LXI Digitizers provide 20 MHz simul-
Impedance
cell technologies requires exhaustive taneous acquisition with floating AC Spectroscopy
characterization of devices in both coupled measurements for increased
stacked and segmented configurations resolution. Agilent’s N3302A Electronic Fuel cells, in common with other
using Electrochemical Impedance Loads, modulated with the Agilent electrochemical cells, exhibit com-
Spectroscopy. 33220A Function/Arbitrary Waveform plex impedance characteristics that
Generator, are used to provide synchro- result in a non-linear voltage/current
In a stacked configuration multiple fuel nized, variable load conditions. relationship. In order to measure
cells are connected in series and mea- electrochemical impedance an AC
surements are made across each cell. The system is controlled by a personal current is applied to the cell and the
In a segmented configuration the fuels computer that includes a software resulting voltage is measured. The
cells are connected to a common anode implementation of a lock-in amplifier. response is an AC voltage signal
and then measurements are made at The Lock-In Algorithm allows accurate that is out of phase with the applied
each cathode in turn. measurement of frequency and current. To ensure that the cell’s
phase and eliminates the need for a response is pseudo-linear a small
The characterization of both of these hardware-based implementation using input signal is used that constrains
configurations requires multi-channel DSP. The LXI connectivity provided the output range to the linear portion
measurements to be made under by the L4534A digitizers allows com- of the curve.
variable loads and under controlled munication between the system and the
environmental and gas conditions. controlling PC over an industry standard The analysis of the response requires
GBit LAN. This supports the fast trans- frequency and phase components to
fer of the large blocks of data necessary be extracted. This is commonly
to calculate the frequency and phase undertaken using Fast Fourier
response of the individual cells. Transforms or a Lock-in Amplifier
and is displayed with Nyquist Plots.
The LXinstruments Fuel Cell Test EIS measurements have traditionally
System uses standard equipment from required specialized test equipment
Agilent Technologies together with that is high cost and limited in
proprietary software to provide a fully channel count. The LXinstruments
The LXinstruments Fuel Cell Test modular and affordable system for Fuel Cell Test System overcomes this
System uses the Agilent L4534A making EIS measurements allowing you by utilizing commercial off-the-shelf
LXI Digitizer with four differential float- to characterize your fuel cell designs test equipment and a software imple-
ing inputs to provide the multi-channel in both stacked and segmented mentation of a Lock-in Amplifier.
measurement capability required. The configurations.

2. Fuel Cell Characterization
www.agilent.com
cathode Agilent
membrane L4534A For more information on Agilent
Agilent Technologies’ products, applications
anode Digitizer 33220A or services, please contact your local
AFG Agilent office. The complete list is
available at:
cathode Agilent Agilent Agilent www.agilent.com/find/contactus.
membrane L4534A N3302A N3302A
anode Digitizer Load Load www.agilent.com/find/lxi
Agilent is co-founder of the LXI
Fuel Cell in Consortium. For specifications visit
Stacked Configuration the LXI Consortium web site at
www.LXIstandard.org
Agilent
33220A
AFG
Agilent Agilent
N3302A N3302A For more information on
Load Load LXinstruments
www.lxinstruments.com
cathode cathode
E-Mail: info@lxinstruments.com
LXinstruments GmbH
membrane membrane
Herrenberger Str. 130
anode 71034 Böblingen
Fuel Cell in
Segmented Configuration Agilent Tel: 07031 410089-0
L4534A
Digitizer
Ordering Information LAN eXtensions for instrumentation
Agilent Technologies
Product specifications and descriptions in
L4534A 4 CH, 20 MSa/s Digitizer this document subject to change without
N3300A Electronic Load Mainframe notice.
N3302A Electronic Load
© Agilent Technologies, Inc. 2010
33220A Arbitrary Function Generator Printed in USA, February 26, 2010
5990-5371EN
LXinstruments
System Design & Engineering Services
• Customized Fuel Cell Test System with 19” Rack, integrated
Industrial PC and internal wiring
• Customized Fuel Cell Test Software (functionality based on
customer requirements)
• On site installation Customer Education and Uptime Support Services