026007
SOFC Technology Trend in Japan
"2007 Fuel Cell Technology Trend Research Report in
Japan", recently released from JPO,
is 421 pages long. A digest version of the report is about 50 pages. The
digest version is available through the internet.
The papers as
well as the patent applications were searched for in the research report.
A table of contents of the research report is attached to the
end of this report, for reference.
The types of
fuel cells searched are PEFC, DMFC, PAFC, and SOFC.
Only SOFC is selected from those fuel cells and reported here referring
to the digest version. It is believed that the FC technology trend research
is very high in completeness and accuracy since it was made by JPO.
It is also believed
that the technology trend research is based on the analysis of the patent
application information and the papers, and provides various and useful
information in selecting and determining research/development themes
and directions and in building management and research/development strategies.
To learn more
and if you have some questions, ask JPO.
The research report is available only in Japanese.
1. Introduction
2. SOFC
Patent Applications
2.1 Transition of SOFC Patent Applications
2.2 Application Trend for Each technical items
2.3 Electrolyte Patent Applications
2.4 Application Trends in Selected Industrial Fields
a) Automobile
b) Electric/Electronics
c) Heavy Industry
d) Energy
e) Material
3. Pedigree
Diagram Of Low/Medium Temperature Electrolyte Key Patents
1) To thin YSZ electrolyte
2) To use other electrolytes than YSZ electrolyte of high conductivity
4. Small/Micro SOFC Stacks
5. SOFC Technology
Trend Based on Analysis of Non-patent Documents (Papers)
1. Introduction
SOFC uses a ceramic solid electrolyte and operates at high
temperature, 1000oC or higher, and has a high energy conversion efficiency.
It is expected as the next generation fuel cell. Westinghouse (U.S.A.)
has developed this technology. SOFC has been developed as the fuel cell
for large-scale combined generator of several hundreds kW since it operates
at high temperatures.
Recently, the
SOFC electrolytes operable at medium and low temperatures have been
developed. The SOFC, which uses the electrolyte of the medium-low temperature
type, is operable at medium-low temperature. In case where the SOFC
is operable at medium-low temperature, many advantages are produced.
Start/stop operation of the fuel cell is simple. Ceramic deterioration
by thermal impact at the time of raising temperature is lessened, leading
to durability improvement. Manufacturing cost is reduced. Further, relatively
inexpensive and easy-to-be worked material, for example, stainless steel,
may be used for manufacturing the SOFC, while using SOFC's special feature
of the internal reforming (hydrogen generation within the module) to
full advantage. Use of such a material leads to remarkable reduction
of material and manufacturing cost.
A residential SOFC
cogeneration system of 1 kW was developed by KYOCERA Corporation and
has been demonstration tested from November 2005. SOFC cogeneration
systems of 1 to 2 kW were developed by KYOCERA Corporation, Mitsubishi
Materials Corporation, and TOTO Ltd. , and have been demonstration tested.
Those cogeneration systems will actually be marketed in around 2008.
Those cogeneration systems have already been reported in our site. If
interested, please make search from the "Search Our site"
window in the site.
Small and micro-SOFCs have trially been manufactured.
2. SOFC Patent Applications
2.1 Transition of SOFC Patent Applications
The research period: 1998 to 2004.
A curve representative of the number of the patent applications in Japan
relatively sharply ascends from 2001 to 2003.
Curve profiles of the application number increase in the US and Europe
during this period resemble that in Japan.
In Japan, the number of patent applications in 2003 is substantially
equal to that in 2004.
The number of SOFC applications is a little over 10% of the total number
of fuel cell patent applications (PEFC, DMFC, MCFC, PAFC, SOFC). <Fig.
2-7-1>.
2.2 Patent Applications
of Selected Technical Items
The technical items selected for the search are: electrolyte,
fuel electrode, air electrode, support member, separator, unit cell,
module, operation, reforming, power generation, and others.
The number of the patent applications of the modules is ranked at the
top, and the electrolyte, which is ranked next to the module, the operation
and the single cell are descendingly ranked in this order.
The number of the module patent applications is much larger than those
of other technical items.
This trend of the patent applications is found also in the US and Europe.
<Fig. 2-7-3>
2.3 Electrolyte Patent
Applications
The research indicates that the SOFC research/development
is targeted mainly at module manufacturing processes and increasing
the ion conductivity of electrolytes, particularly those operating at
medium and low temperatures.
The patent applications of medium-low temperature operating electrolyte
occupy 66 % of the total number of electrolyte patent applications.
The YSZ (of the high temperature type) patent applications reduced in
number, while the number of patent applications of medium-low temperature
electrolytes and the low-temperature type electrolyte having proton
conductivity increased.
From this, it is seen that how to increase the ion conductivity is the
most important technical subject for the medium-low temperature electrolyte
and the electrolyte having proton conductivity.
For this reason,
the SOFC research was made only of the medium-low temperature SOFC.
The types of the electrolytes
that were searched are:
YSZ type electrolyte, high-, medium- and low-temperature type electrolytes,
proton-conduction type electrolyte, and others.
The percentages of those electrolytes patent applications are:
YSZ : 17%
High temperature: 2%
Medium temperature: 34%
Low-temperature: 19%
Proton conduction: 13
Others: 15%
The percentage
of the patent applications of the medium-low temperature electrolytes,
including the low-temperature proton conduction electrolyte is 66%.
The number of the YSZ electrolyte patent applications decreased. <Fig.
2-7-5>
Correlations
were made between the YSZ type electrolyte, high-, medium- and low-temperature
type electrolytes, proton-conduction type electrolyte, and others, and
ion conductivity, gas permeability, membrane pressure control, mechanical
strength, chemical stability, high temperature stability, low temperature
stability, impurity, and others.
The largest degree of the correlation was present between the medium-low
temperature electrolytes and the proton conduction electrolyte.
<Fig. 2-7-6>
Correlations were
made also between current-collection/power, fuel supply, air/oxygen,
humidifying/temperature, water-exhaustion/air discharge, cooling/heat
exchange, start/stop, low output recovery, safety management, overall
control, and others, and stationary operation, load variation, start
operation, stop operation, emergency operation, outside environment,
sensing, fuel supply system, output utilization system, and others.
The largest degree of correlation was present between the start/stop
and the start operation. This fact implies that the temperature-raising
control is important. <Fig. 2-7-7>
2.4 Patent Applications
in Selected Industrial Fields
a) Automobiles
The basic components of the fuel cell, such as electrolyte,
electrodes fuel electrode, air electrode), support, separator, and module
were applied for patents.
A variety of other technical items than the above were applied for
patents.
b) Electric/electronics
None
c) Heavy Industry
Most of SOFC technologies for patents in this field were
developed by Mitsubishi Heavy Industries, Ltd. and Siemens AG.
Mitsubishi Heavy Industries, Ltd. is constructing the SOFC combined
power generation plant, and continuously and steadily develops the large
scale SOFC.
d) Energy
In this field, the number of SOFC patent applications
sharply increased from 2001. Those patents were applied mainly from
Tokyo Gas Co., Ltd.
The patent applications on operation method and module such as the plate
assembly type cells are relatively large in number.
e) Material
In this field, the companies actively files many applications.
The number of patent applications increased from around 2001. Many technologies
on the cell assembling and module constructing process were applied
for patents.
Development on the electrolyte actively progresses.
Commercialization of the residential SOFC power source comes in sight.
List Of Companies
Searched For
A. Automobiles
1. Nissan Motor Co., Ltd.
2. Toyota Motor Corporation
3. Honda Motor Co., Ltd.
4. Aisin Seiki Co., Ltd.
5. DENSO Corporation
6. Toyota Central R&D Labs., Inc.
7. AQUEOUS RES:KK
8. General Motors (U.S.A.)
9. Ballard Power Systems (Canada)
10. Plug power (U.S.A.)
11. DaimlerChrysler (Europe)
B. Electric/Electronic
12. Matsushita Electric Industrial Co., Ltd.
13. SANYO Electric Co., Ltd.
14. Sony Corporation
15. TOSHIBA Corporation
16. Hitachi, Ltd.
17. Mitsubishi Electric Corporation
18. SAMSUNG SDI Co., Ltd. (Korea)
C. Heavy Industry
19. Mitsubishi Heavy Industries, Ltd.
20. Fuji Electric Holdings Co., Ltd.
21. Ishikawajima-Harima Heavy Industries Co., Ltd.
22. Siemens (Europe)
D. Energy
23. Tokyo Gas Co., Ltd.
24. Osaka Gas Co., Ltd.
E. Materials
25. KYOCERA Corporation
26. Mitsubishi Materials Corporation
27. TOTO Ltd.
3. Pedigree Diagram
Of Low/Medium Temperature Electrolyte Key Patents
Where the operation temperature is lowered, the ion conductivity
of the electrolyte decreases and the power generation performance degrades.
We may have two approaches to the ion conductivity decrease problem;
1) to thin the YSZ electrolyte, and 2) to use other types of electrolytes
than the YSZ electrolyte.
Pedigree charts of key patents of the two approaches were formed.
1) To thin the YSZ electrolyte
The plasma thermal spraying method has been known as
a process for thinning the YSZ electrolyte.
The slurry coat method by TOTO Ltd. has greatly affected later film
thinning processes. < Fig. 2-9-3>
2) to use other types of electrolytes than the
YSZ electrolyte
LSGM electrolyte, SCSZ electrolyte, CeO electrolyte,
etc. are know sfor those electrolytes. The LSGM electrolyte is an LaGaO3
oxide having a perovskite structure, and exhibits an excellent oxygen
ion conductivity. This electrolyte was developed by Oita University
and Mitsubishi Materials Corporation. It was applied for patent in 1997.
This technology has greatly affected later development of medium-low
temperature electrolyte. < Fig. 2-9-4>
4. Small/Micro SOFC
Stacks
To lower the operation temperature of SOFC, the development
to create or find new materials and to thin the membrane is continuously
and powerfully carried out. The patent applications on portable micro-SOFCs,
which are frequently started and stopped, have begun to appear. A small
SOFC having a plane integrated stack structure, developed by KRK, Inc.,
leads others. The patent applications from Hewlett-Packard, Motorola,
etc. follow the KRK's SOFC.
5. SOFC Technology
Trend Based on Analysis of Non-patent Documents (Papers)
The research period: 1990 to 2006.
The following ten journals, which frequently publish the articles concerning
the fuel cell and its related technologies were adopted, and 3,603 papers
were selected for the research.
1. POWER SOURCES
2. ELECTROCHEM SOC
3. US DOE Rep
4. SOLID STATE IONICS
5. Fuel Cell Symposium Proceedings.
6. ELECTROCHIM ACTA
7. HYDROGEN ENERGY
8. J APPL ELECTROCHEM
9. Electrochemistry and Industrial Physical Chemistry
10. SAE TECH PAP SER
The number of papers greatly increased from around 1998.
The percentage of SOFC papers is high, 37%. This figure is comparable
with 39% of PEFC. In the case of the patent applications, PEFC is 83%.
This percentage is outstandingly different from that of the non-patent
documents. In other words, the patent trend is different from the research/development
trend. Recently, the difference becomes smaller. From the data, it will
be understood that many researchers have strong interesting in the SOFC
technology. < Fig. 3-1-1>
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