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GB/T 20042.5-2009 English PDF (GBT20042.5-2009)

GB/T 20042.5-2009 English PDF (GBT20042.5-2009)

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GB/T 20042.5-2009: Proton exchange membrane fuel cell -- Part 5: Test method for membrane electrode assembly

This part of GB/T 20042 specifies the terminology and definition, thickness uniformity test, Pt loading test, single cell polarization curve test, hydrogen crossover current density test, activation overpotential and ohmic polarization overpotential test, electrochemical active area test of membrane electrode assembly (MEA) test methods for proton exchange membrane fuel cells.
GB/T 20042.5-2009
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 27.070
K 82
Proton exchange membrane fuel cell ?€?
Part 5. Test method for membrane electrode assembly
ISSUED ON. APRIL 21, 2009
IMPLEMENTED ON. NOVEMBER 01, 2009
Issued by. General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of the People's Republic of
China.
Table of Contents
Foreword . 3
1 Scope .. 4
2 Normative references . 4
3 Terms and definitions . 4
4 Thickness uniformity test . 7
5 Pt loading test . 8
6 Single cell polarization curve test . 11
7 Hydrogen crossover current density test . 18
8 Activation overpotential and ohmic overpotential test .. 20
9 Electrochemical active area test . 22
Appendix A (Informative) Test preparation . 24
Appendix B (Informative) Test report .. 25
Appendix C (Informative) Fuel cell internal resistance and reaction resistance test . 28
Proton exchange membrane fuel cell ?€?
Part 5. Test method for membrane electrode assembly
1 Scope
This part of GB/T 20042 specifies the terminology and definition, thickness uniformity test, Pt loading test, single cell polarization curve test, hydrogen crossover current density test, activation overpotential and ohmic polarization overpotential test, electrochemical active area test of membrane electrode assembly (MEA) test methods for proton exchange membrane fuel cells.
This part applies to various types of proton exchange membrane fuel cells. 2 Normative references
The provisions in following documents become the provisions of this part through reference in GB/T 20042. For the dated references, the subsequent amendments (excluding corrections) or revisions do not apply to this Standard; however, parties who reach an agreement based on this Standard are
encouraged to study if the latest versions of these documents are applicable. For undated references, the latest edition of the referenced document applies. GB/T 5816-1995 Catalyst and adsorbents - Determination of surface area
GB/T 6672-2001 Plastics film and sheeting - Determination of thickness by mechanical scanning (ISO 4593.1993, IDT)
GB/T 19596 Terminology of electric vehicles (GB/T 19596-2004, ISO
8713.2002, NEQ)
GB/T 20042.1 Proton exchange membrane fuel cell - Terminology
3 Terms and definitions
The terms and definitions defined in GB/T 19596 and GB/T 20042.1 and the following terms and definitions apply to this part.
3.1
Platinum loading
Ri,e - Electronic resistance, in ohm square centimeter (??? ?€? cm2);
Ri,c - Contact resistance, in ohm square centimeters (??? ?€? cm2).
3.6
Activation overpotential
The electrode potential loss as caused by the accumulation of particles of certain charge at the electrode surface when the electrochemical reaction speed of the electrode surface is fast, whilst the kinetic speed of the electrode process is slow, it is also known as the electrochemical polarization overpotential. The unit is V.
Note. The activation polarization overpotential usually consists of anodal activation polarization overpotential and cathodic activation polarization overpotential. For PEMFC, since the exchange current density of the
cathode reaction is much smaller than the exchange current density of the anode reaction (about 106), the activation polarization overpotential of the cell is mainly caused by the cathode activation polarization overpotential. 3.7
Ohmic overpotential
The potential loss due to the ohmic polarization of the fuel cell, in units of V. Note. The ohmic overpotential mainly comes from the electrolyte resistance (such as proton exchange membrane and proton conductor) against the flow of ions. Ohmic loss follows Ohm's law.
Where.
??ohm - Ohmic overpotential, in volts (V);
i - Current flowing through the fuel cell, in amperes (A);
Ri - Fuel cell internal resistance, in ohm square centimeters (??? ?€? cm2). 3.8
Reaction resistance
The magnitude of electrochemical resistance in the catalytic layer, in units of ??? ?€? cm2.
??d - The difference between the maximum and minimum thickness of the
membrane, in micrometers (??m);
dmax - The maximum thickness of the membrane electrode, in micrometers
(??m);
dmin - The minimum thickness of the membrane electrode, in micrometers
(??m).
4.4.2 The average thickness is calculated in accordance with formula (4) Where.
di - Measured thickness of membrane electrode at a certain point, in
micrometers (??m);
n - Number of measurement data point.
4.4.3 Relative thickness deviation is calculated in accordance with formula (5) Where.
S - The relative thickness deviation of the membrane electrode;
di - Measured thickness of membrane electrode at a certain point, in
micrometers (??m);
d - The average membrane electrode thickness, in micrometers (??m).
5 Pt loading test
5.1 Test instruments and equipment
5.1.1 Ion-coupled emission spectroscopy (ICP). The minimum detection limit is ??? 1 ??g/L.
5.1.2 Analytical balance. the precision is 0.1 mg.
5.1.3 Vernier caliper. Measuring range 0 mm ~ 200 mm, measuring precision 0.02 mm.
5.1.4 Muffle furnace.
pressure difference is caused by unstable gas pressure or due to the
MEA leakage.
6.6 Single cell activation
6.6.1 INSTALL the single cell on the fuel cell test platform.
6.6.2 USE the reaction gas as the activation medium, to activate the single cell in accordance with the following operating conditions.
- The cell reaction temperature is 75 ??C;
- Reaction gas relative humidity. relative humidity (RH) 100%;
- Reaction gas stoichiometric ratio. St H2. 1.2, St Air. 2.5;
- Outlet back pressure. gauge pressure 0.1 MPa;
- Current density of cell operation. i ??? 500 mA/cm2;
- Cell operation time. ??? 4h.
Note. The activation condition of the cell may also be provided by the sample supplier or determined by both the testing party and the sample supplier through negotiation.
6.7 Polarization curve test
6.7.1 Cell operating conditions
Single cell polarization curve test is divided into two kinds. normal pressure test and pressurization test.
6.7.1.1 Normal pressure test
- Fuel. H2 with a purity of 99.999%, stoichiometric ratio of 1.2, RH 100%; - Oxidant. standard air composed of 99.999% high purity nitrogen and high purity oxygen, containing oxygen 21%, stoichiometric ratio in 2.5, RH 100%; - Cell temperature. 75 ??C;
- Outlet back pressure. gauge pressure 0 MPa.
6.7.1.2 Pressurization test
- Fuel. H2 with a purity of 99.999%, stoichiometric ratio of 1.2, RH 100%; - Oxidant. standard air composed of 99.999% high purity nitrogen and high purity oxygen, containing oxygen 21%, stoichiometric ratio in 2.5, RH 100%; sample;
Icross - The current value read from the plateau part of the I-t curve of the electrochemical method test (generally taking the current value of about 0.4 V), in the unit of Ampere (A);
SMEA - The effective area of the membrane electrode sample, in square
centimeters (cm2).
8 Activation overpotential and ohmic overpotential
test
8.1 Test instruments
8.1.1 Digital storage oscilloscope.
Note. Recommended bandwidth ??? 500 MHz, sampling rate ??? 1 Gs/s (potential step test time 10 ??s - number 100 ??s; the shorter the sampling period, the better to satisfy the requirements).
8.1.2 Controllable electronic load for fuel cells. current regulation accuracy ??? 0.1 A.
8.2 Test samples
a) sample size. ??? 25 cm2;
b) The test specimen shall be free of wrinkles and shall not be defective or damaged;
c) The number of samples shall meet the requirements of 3 valid tests.
8.3 Test methods
USE the current interruption technology for testing.
8.3.1 ASSEMBLE the membrane electrode test sample into a single cell in accordance with the method in 6.4, CONDUCT single cell leakage test and activation in accordance with the methods described in 6.5 and 6.6.
8.3.2 In accordance with the circuit diagram in Figure 5, CONNECT the
oscilloscope into the fuel cell test system. CONTROL the operating conditions as follows.
8.3.2.1 Normal pressure test
- Fuel. H2 with a purity of 99.99%, stoichiometric ratio of 1.2, RH 100%; From the voltage-time changing curve of the oscilloscope, READ the sudden increase in voltage, as the ohmic loss polarization overpotential Vr, the slow increase in voltage corresponds to the activation polarization overpotential Va. 9 Electrochemical active area test
9.1 Test instruments
9.1.1 Electrochemical potentiometric tester.
9.1.2 Proton exchange membrane fuel cell test platform. Current minimum resolution ??? 0.1 A, voltage corresponding speed ??? 100 ms.
9.2 Test sampling
a) Sample size. ??? 1 cm2, and sealing treatment shall be carried out for the periphery of the effective area of the sample;
b) Test specimens shall be free of oil stain, wrinkles, and defects and damage; c) The number of samples shall meet the requirements of 3 valid tests.
9.3 Test methods
9.3.1 ASSEMBLE the membrane electrode test samples into single cells in accordance with the method in 6.4.
9.3.2 PERFORM single cell leak testing and activation as described in 6.5 and 6.6.
9.3.3 USE high purity N2 to purge the working electrode and its reaction chamber, gas pipeline, etc., the purge time is not less than 4 h.
9.3.4 CONNECT the single cell to the electrochemical integrated test system. 9.3.5 FILL the RH100% H2 into the anode side, as the reference electrode and counter electrode, FILL the RH 100% N2 into the cathode side, as the working electrode.
9.3.6 CONTROL the H2 flow rate to 10 mL/min and the N2 flow rate to 20 mL/min. 9.3.7 CONDUCT the cyclic voltammetry (CV) scan of the single cell in
accordance with the following experimental conditions. After the CV curve is stable, RECORD it.
CV experiment scan...

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