Single cell test methods for polymer electrolyte fuel cell (PEFC)
1 Scope
This document covers cell assemblies, test station setup, measuring instruments and measuring methods, performance test methods, and test reports for PEFC single cells.
Note: The PEFC specified in this document is gaseous hydrogen.
This document is used for evaluating:
a) the performance of membrane electrode assemblies (MEAs) for PEFCs in a single cell configuration;
b) materials or structures of PEFCs in a single cell configuration; or,
c) the influence of impurities in fuel and in air on the fuel cell performance.
Note: This document is only applicable to proton exchange membrane fuel cells, and the test contents may be used as reference to other PEFCs.
2 Normative reference
The following documents contain provisions which, through reference in this text, constitute indispensable provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
ISO/TS 14687-2 Hydrogen fuel — Product specification — Part 2: Proton exchange membrane (PEM) fuel cell applications for road vehicles
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
anode
electrode (3.8) at which the oxidation of fuel (3.11) takes place
3.2
catalyst
substance that accelerates (increases the rate of) a reaction without being consumed itself
Note: The catalyst lowers the activation energy of the reaction, allowing for an increase in the reaction rate.
3.3
catalyst-coated membrane
CCM
membrane whose surfaces are coated with a catalyst layer (3.4) to form the reaction zone of the electrode (3.8)
Note: See also membrane electrode assembly (MEA) (3.19).
3.4
catalyst layer
porous region adjacent to either side of the membrane containing the catalyst (3.2), typically with ionic and electronic conductivity
Note: The catalyst layer comprises the spatial region where the electrochemical reactions may take place.
3.5
cathode
electrode (3.8) at which oxidant (3.22) reduction takes place
3.6
clamping plate
pressure plate
frame used to compress the cell components together to maintain electrical conductivity and sealing
3.7
current collector
conductive material in a fuel cell (3.12) that collects electrons from the anode (3.1) side or conducts electrons to the cathode (3.5) side
3.8
electrode
electronic conductor (or semi-conductor) through which an electric current enters or leaves the electrochemical cell as the result of an electrochemical reaction
Note: An electrode may be either an anode (3.1) or a cathode (3.5).
[Source: GB/T 28816-2020, 3.33]
3.9
electrolyte
liquid or solid substance containing mobile ions that render it ionically conductive
Note: The electrolyte is the main distinctive feature of the different fuel cell technologies (e.g. a liquid, polymer, molten salt, solid oxide) and determines the usable operating temperature range.
[Source: IEC 60050-482: 2004, 482-02-29, modified — the note has been modified]
3.10
flow plate
conductive plate made of metal, a material such as graphite, or a conductive polymer that may be a carbon-filled composite, which is incorporated with flow channels for fuel (3.11) or an oxidant (3.22) gas feed and has an electrical contact with an electrode (3.8)
3.11
fuel
hydrogen or hydrogen-containing gas that reacts at the anode (3.1)
3.12
fuel cell
electrochemical device that converts the chemical energy of a fuel (3.11) and an oxidant (3.22) to electrical energy (DC power), heat and reaction products
Note : The fuel and oxidant are typically stored outside of the fuel cell and transferred into the fuel cell as they are consumed.
[Source: GB/T 28816-2020, 3.43]
3.13
gas diffusion electrode
GDE
component on the anode (3.1) or cathode (3.5) side comprising all electronic conductive elements of the electrode (3.8), i.e. gas diffusion layer (3.14) and catalyst layer (3.4)
3.14
gas diffusion layer
GDL
porous substrate placed between the catalyst layer (3.4) and the flow plate (3.10) to serve as electric contact and allow the access of reactants to the catalyst layer and the removal of reaction products
Note: The gas diffusion layer is also called a porous transport layer (PTL).
[Source: GB/T 28816-2020, 3.57, modified — "flow plate" replaces "bipolar plate" and note modified.]
3.15
gasket
sealing component which prevents the reactant gas from leaking out of a cell
3.16
internal resistance
ohmic resistance inside a fuel cell (3.12), measured between current collectors (3.7), caused by the electronic and ionic resistances of the different components (electrodes (3.8), electrolyte (3.9), flow plates (3.10) and current collectors)
Note : The term ohmic refers to the fact that the relation between voltage drop and current is linear and obeys Ohm’s Law.
[Source: GB/T 28816-2020, 3.66, modified — "flow plates" replaces "bipolar plates"]
3.17
limiting current density
maximum current density that can be attained by the cell under a given set of test conditions where the cell voltage sharply decreases to near zero
3.18
maximum current density
highest current density allowed for a short time as specified by the manufacturer
3.19
membrane electrode assembly
MEA
component of a fuel cell (3.12), usually PEFC (3.24), consisting of an electrolyte membrane with gas diffusion electrodes (3.13) on either side, or consisting of CCM (3.3) and gas diffusion layer
Note: Membrane electrode assembly is abbreviated as membrane electrode.
3.20
minimum cell voltage
lowest permitted cell voltage specified by the manufacturer
3.21
open circuit voltage
OCV
voltage across the terminals of a fuel cell (3.12) with fuel (3.11) and an oxidant (3.22) present and in the absence of external current flow
Note : The open circuit voltage is expressed in V.
Note : Also known as "no-load voltage".
[Source: GB/T 28816-2020, 3.117.2]
3.22
oxidant
oxygen or oxygen-containing gas (e.g. air) that reacts at the cathode (3.5)
3.23
polymer electrolyte
polymer material containing mobile ions that render it ionically conductive
3.24
polymer electrolyte fuel cell
PEFC
fuel cell (3.12) that employs a polymer with ionic exchange capability as the electrolyte (3.9)
Note: The polymer electrolyte fuel cell is also called a proton exchange membrane fuel cell (PEMFC) and solid polymer fuel cell (SPFC).
[Source: GB/T 28816-2020, 3.43.7]
3.25
power
energy per unit time, calculated from the voltage multiplied by the current
3.26
power density
measure calculated by dividing the power by the geometric electrode area
Note: Power density is expressed in W/cm2.
3.27
rated current density
maximum current density specified by the manufacturer of the MEA (3.19) or single cell (3.29) for continuous operation
3.28
rated voltage
minimum cell voltage specified by the manufacturer of the MEA (3.19) or single cell (3.29) for continuous operation
3.29
single cell
cell typically consisting of an anode flow plate (3.10), MEA (3.19), cathode flow plate (3.10) and sealing gaskets (3.15)
Note: See Annex B for additional information.
3.30
single cell test
test of the fuel cell (3.12) performance based on a single cell (3.29)
[Source: GB/T 28816-2020, 3.112.5]
3.31
stoichiometry
molar ratio of the fuel (3.11) or oxidant (3.22) gas flow rate supplied to the cell to that required by the chemical reaction, as calculated from the current
Note: This is the inverse value of fuel (or oxidant) utilization as defined in GB/T 28816-2020.
4 General requirements for safety
An operating fuel cell uses oxidizing and reducing gases. Typically, these gases are stored in high-pressure containers. The fuel cell itself may or may not be operated at pressures greater than atmospheric pressure.
Those who carry out single cell testing shall be trained and experienced in the operation of single cell test systems and specifically in safety procedures involving electrical equipment and reactive, compressed gases. Safely operating a single cell test station requires appropriate technical training and experience as well as safe facilities and equipment, all of which are outside the scope of this document.
5 Cell components
5.1 General
The following components are typically used:
a) an MEA,
b) gaskets,
c) an anode-side flow plate and a cathode-side flow plate,
d) an anode-side current collector and a cathode-side current collector,
e) an anode-side clamping plate and a cathode-side clamping plate,
f) electrically insulating sheets,
g) clamping or axial load hardware which may include bolts, washers, springs, etc., and,
h) temperature control devices.
5.2 Membrane electrode assembly (MEA)
The electrode area shall be as large as needed to measure desired parameters. A suggested electrode size should be approximately 25 cm2, though cells having larger electrodes may give more relevant data for practical applications. The active electrode area shall be recorded. The approximate uncertainty in the area measurement shall also be recorded.
Note: For a larger active area, heterogeneities in parameters such as temperature, flow rate, and/or compression can become significant.
Foreword i
1 Scope
2 Normative reference
3 Terms and definitions
4 General requirements for safety
5 Cell components
5.1 General
5.2 Membrane electrode assembly (MEA)
5.3 Gasket
5.4 Flow plate
5.5 Current collector
5.6 Clamping plate (or pressure plate)
5.7 Clamping hardware
5.8 Temperature-control device
6 Cell assembly
6.1 Assembly procedure
6.2 Cell orientation and gas connections
6.3 Leak check
7 Test station setup
7.1 Minimum equipment requirement
7.2 Schematic diagram
7.3 Maximum variation in test station controls (inputs to test)
8 Measurements
8.1 Instrument uncertainty
8.2 Measuring instruments and measuring methods
8.3 Measurement units
9 Gas composition
9.1 Fuel composition
9.2 Oxidant composition
10 Test preparation
10.1 Standard test conditions
10.2 Ambient conditions
10.3 Data sampling rate
10.4 Repeatability and reproducibility
10.5 Number of test samples
10.6 Leak check of gas circuit with inert or test gas
10.7 Initial conditioning and stable state check
10.8 Shutdown
10.9 Reconditioning
11 Basic performance test methods
11.1 General
11.2 Polarization curve tests
11.3 Steady-state test
11.4 Long-term operation test
11.5 Voltammetry
11.6 Internal resistance (IR) measurement
11.7 Electrochemical impedance spectroscopy (EIS)
12 Applied performance test methods
13 Test report
13.1 General
13.2 Report items
13.3 Test data description
13.4 Description of measurement conditions
13.5 Test cell parameter description
Annex A (Informative) Flow plate
Annex B (Informative) Cell component alignment
Annex C (Informative) Air tightness test
Annex D (Informative) Initial conditioning
Annex E (Informative) Shutdown
Annex F (Informative) Reconditioning protocols
Annex G (Informative) Polarization curve test supplement
Annex H (Normative) Applied performance tests
Annex I (Informative) Test report for polarization curve tests
Annex J (Informative) Polarization curves in helox
Annex K (Informative) Test report for subzero start test
Annex L (Informative) Start/stop cycling test supplement
Annex M (Informative) Load cycling supplement
