8. Task ８ Development of Hydrogen Production Technology
8.1 Research and Development Goals
This study is directed to establish hydrogen production technology inelectrolysis of water by means of Solid Macromolecular Electrolyte Method that is
expected to be more efficient and less costly than traditional hydrogen production
methods. In the fiscal year 2001 as third year of WE-NET 2 nd stage, along with thedevelopment of large area electrolysis cell lamination (electrolysis area:2,500cm 2
10 cells ) and continuous operation of the electrolyte for commercialization of,
production

technology,

manufacturingofelectrolysis

cell(electrodearea

1,000cm 2 ,25cells) for hydrogen refueling station in connection with the Task 7(the development of hydrogen refueling station) will be implemented.
And, also, a few different type of high temperature resistant molecule electrolyte
membrane to be usable in high temperature will be manufactured and evaluatedits ion conductivity and electrolysis performance of the membrane.
Outline of this report is presented below.
8.2 Results in fiscal year 2001
8.2.1 Development of Hydrogen Production Technology by Electroless Plating
8.2.1.
8.2. 1.1
1. 1 Targets of Research & Development Work
1.1 Improvement of the long-term durability
1.2 Study of optimization of the cell construction
1.3 Development of large-area cell stacking technology
1.4 Experimental production of the cell stack for hydrogen refueling station
8.2.1.2
8.2.1. 2 Improvement of the longlong - term durability
Considering its practical operation, we conducted a long-term durability
evaluation using the water electrolysis cell stack. The result is shown in Fig.8.2.1-1.
As shown in the figure, there was little decrease of energy efficiency even after 400
cycles of operation starts and stops and it was also confirmed that energy efficiency
of about 90％ could be kept at operating temperature of 373K even after 400 cycles
of starts and stops. Fig.8.2.1-2 shows appearance of 10 cells layered stack used forthis electrolysis test. We decided to adopt the equivalents of the cells used in thisdurability test to the electrolysis stack for hydrogen refueling station.

‑63‑

100

Energy Efficiency (%)

90

80

70
10 cells stack
2 hours operation
30 minutes pause
2 - 3 times start and stop per day

60

50

0

50

100

150

200

250

300

350

400

Number of Operation Cycles

Fig.8.2.1
Fig. 8.2.18.2.1 - 1

1010 - cells stack electrolysis test results, 1,000cm 2 cells＜Testconditions＞･ Cell area size: 1,000cm 2 (10 cells)･ Operating pattern: Electrolysis 2Hr/Pause 30min.
･Operatingconditions:Temp.353K/Press.0.7MPa･ Current density: 1A/cm 2

Fig.8.2.1
Fig. 8.2.18.2.1 - 2

Appearance of electrolysis test using 10 cells layered stack(Cell electrode area size: 1,000cm 2 )8.2.1.3.
8.2.1. 3. Study of optimization of the cell construction
Based on the flow analysis results of the water distribution (header part) fromthe separator and the layered cell stacks, we designed and trially made a 2,500 cm 2
separator, and 1,000cm 2 separator for H 2 refueling station, as well as cell stacks forboth of them, to conduct their evaluation tests.
8.2.1.4.
8.2.1. 4. Development of largelarge - area cell stacking technology‑64‑For the evaluation test of 2,500cm 2 cell stack, we enhanced our test facilities by
newly adding a D.C. current power source (DC50V-7, 500A spec.), etc. We produced
and assembled the 2,500cm 2 cell stack using the same production method for thecell stack for H 2 refueling station.
Fig.8.2.1-3 shows the membrane electrode assembly as produced and Fig8.2.1-4 theappearance of the separator. The cell showed a very good catalyst support condition
to the electrolyte membrane without showing appearance of non-uniformity.
Regarding the 2,500cm 2 cell, we produced and evaluated 2-cells stack. Fig.8.2.1-5
shows the view of the experiment and Table8.2.1-1 the test results. The targetedenergy efficiency of over 90% could be achieved as in the case of the 1,000cm 2 cellstack.

Fig.8.2.1
Fig. 8.2.18.2.1 - 3 M embrane electrode assembly
assembl y (entire view)(cell electrode area size: 2,500cm 2 )Fig.8.2.1
Fig. 8.2.18.2.1 - 4 Separator (entire view)‑65‑

Table 8.2.18.2.1 - 1 Test results of 22 - cells layeredstack(cell area size: 2,500cm 2 )ItemSpecification

Cell area size

2,500cm 2

Number of cells

2Electrolysis temp.

353K

Current density

1A/cm 2Current efficiency

98.8％

Energy efficiency

91.1％

Fig.8.2.1Fig.8.2.1 - 5 (２( ２ cells stack,2500cm 2 )8.2.1.5

Experimental production of cell stack for H 2 refueling station

The cell stack for the H 2 refueling station uses 25 cells of 1,000 cm 2 layered
per stack, and this cell stack has been installed for two units of the station system.
Appearance of the 25-cells stack is shown in Fig. 8.2.1-6. Also, the systemelectrolysis pressure has been set at 0.6MPaG, and the system configuration is suchthat no further gas compressor is required after the gas production.
The PEM water electrolysis hydrogen production system for H 2 refueling station
was installed at Shikoku Research Institute Inc. (in Takamatsu City, Japan) in
December 2001, and its operational adjustment and its initial performance test
have been conducted since January, 2002. Results of its initial performance test are
given in Table 8.2.1-2. As shown in the table, achievements of its initial target
performances as the water electrolysis unit could be successfully confirmed.
We are planning to have test operation connecting metal hydride, high pressure gas
compressor, and dispenser to verify the adaptability for H 2 refueling station.

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Specification of the 25 cells layered stack
Cell area size

: 1,000cm 2

Layered cells/stack : 25 cells/stack
Electrolysis press. : 0.6MPaG

F i g .8 .2 .1 - 6 1 ,0 00 c m ２ 、 25 c el ls s t a c k
Table8.2.1
Table 8.2.18.2.1 - 2

Item
H2
production rate
Current
density

Results of initial performance
performan ce test of PEM water electrolysis
system for H 2 refueling station
Test results
Specification(normal)20/30Nm 3 /h
20.6Nm 3 /h(Nor./Max.)

Test results(max.)
30.3Nm 3 /h

1.0/1.5A/cm 2

1.0A/cm 2

1.5A/cm 2

Pressure

0.5MPa G

0.507MPa G

0.522MPaG

Energyefficiency＞90％ (at normal)

90.3%

85％
(Reference value)

Dew point＜−213K

−213K

−213K

Oxygen conc.

＜10ppm1ppm

1ppm

Test conditions
Cell area size; 1,000cm 2
Numbers of cells/stacks; 50 cells (25 cells×2 stacks)
Electrolysis temperature; 354K

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8.2.1.6.
8.2.1.6 . Conclusion
In the first half of this fiscal year, we devoted our research anddevelopmental efforts especially to optimization of the specification for thecell stacks for H 2 refueling station as well as their production technology.
As a result, we could achieve the successful results of development of the PEM
water electrolysis type H 2 production system as shown in this paper bytackling development of 1,000cm 2 -cell stack which could be available forpractical operation in terms of its performance and durability. We are now inthe stage of our evaluation of the initial performances of the cell, stack andsystem unit through production of the water electrolysis cell stacks and theirassembly into the PEM water electrolysis type H 2 production system for H 2
refueling station.
In future, we will advance the system verification as the H 2 refuelingstation to conduct its adaptability assessment.
With regard to 2,500cm 2 cell stack, we could also verify its targeted
performance by experimentally producing the cell stack through utilization of
our know-how on the 1,000cm 2 cell stack for H 2 refueling station. In future, we
intend to utilize those successful results to advance practical use of this cellstack.

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8.2.2Development of Hydrogen Production Technology by Hot Press Method
Met hodThis is to develop manufacturing technology of a large-scale electrolytic cell
utilizing solid high molecule electrolytic membrane. A large-scale electrolytic cellwith 10 cell- laminated electrolytic cell manufactured in the previous year wastested for continued operation. Further, improved production technology for thelarge-scale electrolytic cell and operation technology under high pressure andtemperature were developed. Following results are noteworthy.
8.2.2.1.
8.2.2.1 . Result of Continued Operation Test
Te st for a Large Scale Electrolytic Cell with
10 CellCell - Laminated Electrolytic Cell
A large-scale electrolytic cell with 10 cell- laminated electrolytic cell manufactured
in the end of the year 2000 was tested for continued operation. The accumulated
test duration was extended to approximately 5,700 hours. The operation history of
the test is shown in Fig. 8.2.2-1.
As observed, the initial energy efficiency was 94% but it started to drop after 1100
hours when average electrolytic pressure of the cells rose all of sudden. Thereafter
the efficiency kept dropping as the electrolytic pressure kept rising. Currently theenergy efficiency is in the level of 84%.
A sudden increase of electrolytic pressure at 1100 hour operation is considered as aresult of deterioration of electrolyte water quality.

Current Effic ienc y %Efficiency %

100
90
80
Energy Effic ienc y %7060

Average Cell Voltage (V)

50
0

1000

2000

3000

4000

5000

6000

7000

0

1000

2000

3000

4000

5000

6000

7000

1.90
1.85
1.80
1.75
1.70
1.65
1.60
1.55
1.50
Cumulative O peration time (hour)

Operating condition : 80℃, Atmospheric pressure
Fig8.2.2-1 History of Electrolysis Operation Test in the 2,500cm 2 , 10-Cell Stack Electrolyzer‑69‑8.2.2.2
8.2.2. 2 Development of Manufacturing Technology of Large Scale Membrane
E lectrode AssemblyWith the purpose of improvement in stabilizes production quality of a large scale
cell, further improvement in production method of MEA (Membrane Electrode
Assembly) was implemented in this year. Specific emphasis was made in thefollowing aspects.
(1) Improvement in catalytic layer production procedure.
In the catalytic layer production of a large scale MEA, following two aspects areimportant for production stabilization, which were thoroughly reviewed.
①

Deviation of catalytic suction.

Deviation of catalytic suction is caused by insufficient hydrophilitic treatment of
membrane filter used for production of catalytic layer. Relationship among theamount of solvent added during hydrophilitic treatment, homogeneous catalytic
suction and the repeatability was studied, and the optimum mixing ratio wasattained so that catalytic layer without deviation in the catalytic suction was madeproduced.
② Damage of MEA and sealing defective (Review of strainer frame dimensions.).
Review of strainer frame dimensions was made to protect from MEA damage andsealing defective. On the electrolytic membrane adjacent to the edges of thecatalytic layers, there observed phenomena in the mechanical shortcomings such as
emergence of wrinkles caused by dimensional change when MEA hot water
expanded. It was presumed that MEA damage and sealing defective were caused by
too close a position or direct contact of seal packing to edges of catalytic layers.
Thus, analyzing dimensional deviations when MEA hot water expanded, optimum
dimensions of the frame for catalytic layer formation( the frame for strainer) not tointerfere with sealing area were developed.
(2) Improvement in assembly procedure of MEA free from assembly defect andwrinkling.
When a large scale MEA is hot-pressed, fine wrinkles on the electrolytic surface
around edges in the lengthwise were generated. These wrinkles result in MEA
defective in the production process or damage of the membrane. In view of expected
longer life of the cells, such wrinkles should be minimized. The cause of thewrinkles was found to be the heterogeneous pressure applied during hot-pressing.
Some countermeasures were developed not to generate heterogeneous pressure
application. As the result, wrinkles particularly around boundaries of catalytic
layers and electrolytic membranes were significantly reduced.

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(3) Research of internal characteristic distribution of a large scale cells.
On a large scale cell produced being incorporated to above descried improvements,
internal deviations of the cell characteristics was studied. A part of the prototype
large scale cell, 50 cm 2 in size, was cut off for the analysis. It was confirmed that
there was no difference in the extent of deviation of electrolytic characteristics
comparing to the whole cell as a unit.
8.2.2.3 Improvement in characteristics of power feed assembly on the anode side
It was noted in the prototype manufacturing of the large scale power feed
assembly in the previous year that the cause of deviated thickness was thedeflected loading plate of the horizontal pressing machine. Thus it was intended to
improve the problem in the particular area by modifying the design of the loadingplate, which was the plate directly press the material.
A spherical supporting plate was considered and applied. But there was no
improvement in the deviation of the thickness. Then, a liner was inserted aroundcircumference of the spherical supporting plate. The result was almost the same aswithout the liner in general, however, there was a certain improvement in thedeviation of the thickness in the widthwise of power feed assembly comparing to thelast year output. This achievement was the result of improvement in the stability ofan angle of the plate thickness of the power feed assembly. This was considered asignificant improvement for production of multi layer lamination of cells.
8.2.2.4
8.2.2. 4 Development of High Pressure and High Temperature Operation
Technology(1) Test for High Pressure and High Temperature Electrolysis of Large Scale Cell
High pressure tests for a large scale laminated electrolytic cell with two setsof cells with 2500cm 2 area each were conducted at 80℃ temperature and theheat balance was calculated. The test units are shown in Fig 8.2.2-2 andFig.8.2.2-3. Result of heat balance calculation based on electrolysis
characteristic under high pressure is shown in Table 8.2.2-1, fromwhich it was confirmed that there was no need of supplemental heating unit tomaintain temperature in the electrolytic cell as long as the pressure was morethan 0.2Mpa at 80℃ temperature. It was also found that the energy efficiencyof 90% was maintained under atmospheric pressure but it dropped under highpressure due to increased electrolytic pressure.

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T a b l e 8 .2 .2 - 1

Computation results of heat balance

Operatingpressure
MPa

Average cellvoltageV

UsableenergyW

01.605

2108.2

63.6

0.2
0.4
0.6
0.8

1.619
1.628
1.643
1.659

2178.22223.22298.22378.21353.61544.71676.51786.5Heat balance in electrolyzer cell
W
Deficiency in heatconsidering released heat
Excess in heat
Excess in heat
Excess in heat
Excess in heatFig.8.2.2Fig.8.2.2 - 2 Compression Unit of

Fig.8.2.2Fig.8.2.2 - 3 Water/Gas Supply/Discharge

Electrolyzer and 2 - Cell Stack

Unit in Test Stand(2) Evaluation of Characteristics for High Pressure/Temperature Operation ofElectrolytic Cell with 200cm 2 Area Cells.
In order to examine high pressure/temperature conditions, tests for theelectrolytic cell with two units of 200cm 2 area cell were conducted under theconstant temperature 80 ℃ but under various pressures, namely atmospheric,
0.4Mpa and 0.7Mpa. The result of the characteristic is shown in Fig. 8.2.2-4. As
noticed, as the operating pressure increases, cell voltage increases and energy
efficiency decreases. In the case of current density 1A/cm 2 , the cell voltage was
1.56V and the energy efficiency was 94% under atmospheric pressure, while thevoltage was 1.62V and the energy efficiency was 90.5% under 0.7Mpa pressure
condition.
Further the tests proceeded under a constant operating pressure 0.7Mpa but undervaried temperature, namely 80℃, 100℃ and 120℃. Fig. 8.2.2-5 shows the relation
between cell voltage and electrolytic temperature at the current density 1A/cm 2 . As
noticed, as the temperature increases, the electrolytic voltage decreases and the‑72‑

セル電圧V

Average cell voltage

energy efficiency increases.

2.0

80℃ 3A/cm2

1.9
80℃ 2A/cm2

1.8

80℃ 1A/cm2

1.7
1.6
1.5
0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

運転圧力MPa
Operatingpressure MPa

Fig.8.2.2
Fig. 8.2.28.2.2 - 4 Charactaristics of Cell voltage vs. Operating pressure

1.80

100

Operating 圧力0.7MPa一定
Pressure: 0.7MPa

95

1.70

90
1.60

85

1.50
60

80

100

120

80
140

EnergyEfficiency %ｴﾈﾙｷﾞｰ効率%

Averagecell voltage
セル電圧V

at 1A/cm 2 ,2A/cm 2 and 3A/cm 2 in 200cm 2 - Cell

電解温度℃
Operating Temperature℃
Fig.8.2.2Fig.8.2.2 - 5 Charactaristics of Cell voltage and Energy efficiency vs. Operating
temperature at the operating pressure 0.7MPa in 200cm 2 - Cell

5. Endurance Test of Small Cell
Endurance test of the small cell had been conducted in the two aspects. One was forsmoothness of the cell surface as electrical feed material and another was the life of
the cell itself. In order to improve smoothness of the cell surface, introduction of
new materials and improvement of a material by means of additives had beenstudied. In the current year, influence of gaps generated when the cell was formedby pressing and evaluation of two kinds of new material were studied.
Study was made in the following aspects.
(1) Cell No. 3 : Titanium Fine Fiber Sintered Plate.( There were gaps from pressing)
Currently the test duration of the cell No. 3 has been passed over 1500 hours.
It was proved that this cell had the highest stability in characteristics among‑73‑

those produced in 2001. Smoothness on the feed surface processed by pressing
must be in the high grade.
(2)Cell No. 4: Titanium Ultra Fine Fiber Sintered Plate.
(Fiber diameter φ20μm. It was intended without pressing.)
Cell No. 4 was tried with an intention to eliminate pressing process, howevera short circuit was noted after 500 hours of continuous test of the small cell.
The unit was examined in detail and it was found that Ry (Rmax) value of thesurface roughness of the feed material supplied by Company A was no better
than conventional titanium fine fiber sintered plate. On the other hand,surface roughness of the titanium ultra fine fiber sintered plate, a feedmaterial proposed by Company B consisting of the same fiber with diameter φ
20μm, was found to be better in grade comparing to one supplied by Company
A. The test is planned in the future.
(3)Cell No. 5: Titanium Spherical Powder Sintered Plate.
(The new material and the processing method were evaluated.)
Because of spherical powder of the element, the feed material made of
Titanium spherical powder sintered plate should have better smoothness
without showing sharp bosses on the surface. It was wondered if internalcleanliness was improved by means of platinum spattering plating comparing
to conventional electrolytic plating which had been applied to titanium powder
sintered plate made in the year 2000. But in the actual operation, majority of
the influence was apparent on the part of the quality of the circulating waterthat was affected by the cell voltage. In the future, the cause of the increased
cell voltage needs to be studied considering quality of the circulating waterand deterioration of the cell material.

8.2.3 Development of High Temperature Resistant Molecule Electrolytic‑74‑

Membrane
In order to newly develop a high molecule electrolytic membrane with improved
conductivity and mechanical properties, three kinds of membrane were synthesized.
They were developed by adding optimized amount of PBI on the composite primarily
made of sulfonic acid etherketone molecule. Those membranes were given to
National Institute of Advanced Science and Technology (AIST) for performance
evaluation.
High molecule membrane 13752-52 ( delivered on 9/2001) and 13752-63 (deliveredon 4/12/2001) were derived from FSPEEK synthesized by optimum sulfonation
method to enable precise control of the extent of sulfonation.

High molecule

membrane 13752-52 (delivered on 9/2001) was derived from FSPEEK that had low
sulfonation. Thus water absorption rate and ion conductivity were rather low,while high molecule membrane 13752-63 (delivered on 4/12/2001, 12x12cm in size)
was derived from FSPEEK of which sulfonation was known to be optimum(sulfonation 80%). On the other hand, development of synthesis of PEEK based on
fluorinated sulfonic acid by applying amino-functional silica instead of PBI wasstarted.
It was found that the high molecule membrane 13752-63 had 52% of water
absorption rate (weight% after boiling for 1 hour), 0.073 S/cm of conductivity basedon dried membrane thickness under the room temperature and 0.4 S/cm ofconductivity based on dried membrane thickness of 3.2 μ under 150 ℃ . Thisparticularmembrane

is

the

only

membraneprocessedbyacoater.

The

characteristics of the membrane processed by the coater was found to be different
from those processed by manual casting even though chemical properties were thesame. It is considered that mechanical properties of the membrane processed in thethe coater facility was improved protecting the separation of high moleculecomposite (FSPEEK and PBI) resulted from extremely quick drying process of themembrane.A membrane in the size of 12x90cm was produced in the coater facility
as shown below(Fig8.2.3-1).

Fig.8.2.3Fig.8.2.3 - 1 FSPEEK and PBI A membrane‑75‑

8.2.4 Evaluation of high temperature resistant molecule electrolytic membrane
Evaluation of conductivity rate and water electrolytic performance of the newly
developed temperature resistant high molecule electrolytic membrane have been
conducted. This year, they conducted evaluation of ion conductivity and electrolysis
performance of the membrane in the pure water with varied temperature condition
from 100 ℃ to 150 ℃ . For the membrane with 3.3 mil thickness, relatively
satisfactory performance was obtained at the temperature below100 ℃ , but theperformance dropped at the temperature higher than 100℃. As to ion conductivity,
they were 0.006S/cm at 80℃, 0.07S/cm at 100℃, 0.03S/cm at 120℃ and 0.02S/cm at
150℃. As to electrolytic performance at 1A/cm 2 of the current density, they were
1.7V at 80℃, 1.64V at 100℃ and 1.82V at 120℃.
Voltage efficiencies were approximately 87%, 90% and 81% ( on Δ H basis)
respectively. At the temperature 100℃, the current density was raised to 3A/cm 2 .
The result was 1.95V for electrolytic performance and 75% for voltage efficiency.
It is required to evaluate the membrane at higher temperature and higher current
zone and to develop membrane equipped with improved mechanical properties,
durability and reliability. The currently available membranes are still in the stageof development, thus the mechanical strength of the membrane and its assembly is
far from the required level. Unexpected voltage increase and damage of membrane
happened during evaluation process. Thus, be minded there are still no data
available being measured under stable and sustainable conditions.
8.2.5 Research of Documents related to Water Electrolysis
Water electrolysis is one of the important industrial processes that has beenindustrially practiced to produce hydrogen that is required in the chemical
processing particularly in the ammonia synthesis plant. In these days, hydrogenproduction by steam reformed process on the fossil fuels such as oil and natural gas
seems more dominant in the economical viewpoint, however the importance toproduce hydrogen through water electrolysis that is the only established industrial
method to produce the clean secondary energy has never be faded away. Thoroughreview and study of the research documents in this aspect are extremely important.
Subsequent to the policy in the last year, research of the documents related towater electrolysis published in the technical magazines or similar publications wascontinued in this year limiting the period for one year from 7/2000 to 6/2001. A listof the documents was prepared with description of outline of each report. The
purpose of the list is to enable foreseeing general trend of the researches in thisfield. Thus the details of the individual content should be obtained from theoriginal publication.

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