Fuel Cell Characterization Agilent Technologies and LXinstrumentsModular, multi-channel characterization of stackedand segmented fuel cells ElectrochemicalResearch into the development of fuel LXI Digitizers provide 20 MHz simul- Impedancecell technologies requires exhaustive taneous acquisition with floating AC Spectroscopycharacterization of devices in both coupled measurements for increasedstacked and segmented configurations resolution. Agilent’s N3302A Electronic Fuel cells, in common with otherusing 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/currentIn a stacked configuration multiple fuel nized, variable load conditions. relationship. In order to measurecells are connected in series and mea- electrochemical impedance an ACsurements are made across each cell. The system is controlled by a personal current is applied to the cell and theIn a segmented configuration the fuels computer that includes a software resulting voltage is measured. Thecells are connected to a common anode implementation of a lock-in amplifier. response is an AC voltage signaland then measurements are made at The Lock-In Algorithm allows accurate that is out of phase with the appliedeach 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 smallThe characterization of both of these hardware-based implementation using input signal is used that constrainsconfigurations requires multi-channel DSP. The LXI connectivity provided the output range to the linear portionmeasurements 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 LXinstrumentsThe LXinstruments Fuel Cell Test modular and affordable system for Fuel Cell Test System overcomes thisSystem uses the Agilent L4534A making EIS measurements allowing you by utilizing commercial off-the-shelfLXI 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.