Solid acid fuel cell

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Solid acid fuel cells (SAFCs) are a class of fuel cells characterized by the use of a solid acid material as the electrolyte. Similar to proton exchange membrane fuel cells and solid oxide fuel cells, they extract electricity from the electrochemical conversion of hydrogen- and oxygen-containing gases, leaving only water as a byproduct. Current SAFC systems use hydrogen gas obtained from a range of different fuels, such as industrial-grade propane and diesel. They operate at mid-range temperatures, from 200 to 300 °C. [1] [2]

Contents

Design

Solid acids are chemical intermediates between salts and acids, such as CsHSO4. [3] Solid acids of interest for fuel cell applications are those whose chemistry is based on oxyanion groups (SO42-, PO43−, SeO42−, AsO43−) linked together by hydrogen bonds and charge-balanced by large cation species (Cs+, Rb+, NH4+, K+). [1]

At low temperatures, solid acids have an ordered molecular structure like most salts. At warmer temperatures (between 140 and 150 degrees Celsius for CsHSO4), some solid acids undergo a phase transition to become highly disordered "superprotonic" structures, which increases conductivity by several orders of magnitude. [3] When used in fuel cells, this high conductivity allows for efficiencies of up to 50% on various fuels. [4]

The first proof-of-concept SAFCs were developed in 2000 using cesium hydrogen sulfate (CsHSO4). [1] However, fuel cells using acid sulfates as an electrolyte result in byproducts that severely degrade the fuel cell anode, which leads to diminished power output after only modest usage. [5]

Current SAFC systems use cesium dihydrogen phosphate (CsH2PO4) and have demonstrated lifetimes in the thousands of hours. [6] When undergoing a superprotonic phase transition, CsH2PO4 experiences an increase in conductivity by four orders of magnitude. [7] [8] [9] In 2005, it was shown that CsH2PO4 could stably undergo the superprotonic phase transition in a humid atmosphere at an "intermediate" temperature of 250 °C, making it an ideal solid acid electrolyte to use in a fuel cell. [10] A humid environment in a fuel cell is necessary to prevent certain solid acids (such as CsH2PO4) from dehydration and dissociation into a salt and water vapor. [11]

Electrode Reactions

Hydrogen gas is channeled to the anode, where it is split into protons and electrons. Protons travel through the solid acid electrolyte to reach the Cathode, while electrons travel to the cathode through an external circuit, generating electricity. At the cathode, protons and electrons recombine along with oxygen to produce water that is then removed from the system.

Anode: H2 → 2H+ + 2e−

Cathode: ½O2 + 2H+ + 2e− → H2O

Overall: H2 + ½O2 → H2O

The operation of SAFCs at mid-range temperatures allows them to utilize materials that would otherwise be damaged at high temperatures, such as standard metal components and flexible polymers. These temperatures also make SAFCs tolerant to impurities in their hydrogen source of fuel, such as carbon monoxide or sulfur components. For example, SAFCs can utilize hydrogen gas extracted from propane, natural gas, diesel, and other hydrocarbons. [12] [13] [14]

Fabrication and Production

Sossina Haile developed the first solid acid fuel cells in the 1990s.

In 2005, SAFCs were fabricated with thin electrolyte membranes of 25 micrometer thickness, resulting in an eightfold increase in peak power densities compared to earlier models. Thin electrolyte membranes are necessary to minimize the voltage lost due to internal resistance within the membrane. [15]

According to Suryaprakash et al. 2014, the ideal solid acid fuel cell anode is a "porous electrolyte nanostructure uniformly covered with a platinum thin film." This group used a method called spray drying to fabricate SAFCs, depositing CsH2PO4 solid acid electrolyte nanoparticles and creating porous, 3-dimensional interconnected nanostructures of the solid acid fuel cell electrolyte material CsH2PO4. [16]

Electrode Catalysts

SAFCs, like many other types of fuel cells, utilize electrochemical catalysts on the electrodes to increase cell efficiency. Platinum is the most common choice for SAFCs due to its high reaction activity and stability. [17] [18] Initially, platinum nanoparticles were deposited directly on the electrode surface, but these nanoparticles agglomerated throughout fuel cell operation. [19] [20] Recent studies have incorporated carbon-based supports (carbon nanotubes, graphene, etc.) to reduced agglomeration. [21] [22] Here platinum nanoparticles are deposited directly onto the carbon-based support via processes like atomic layer deposition [23] or metal-organic chemical vapor deposition. [24]

SAFCs have a high tolerance to catalyst poisoning due to the stability of CsH2PO4 at operating temperatures. [25] However, one recent study has proposed local hotspots around the current collector fibers can cause catalyst poisoning. [26] According to Wagner et al. 2021, local hotspots can form a liquid phase of CsH2PO4 that introduces phosphate groups to the platinum catalyst, degrading fuel cell operation. The introduction of a microporous current collector was found to improve the morphological stability of CsH2PO4 and, consequently, mitigate catalyst poisoning.

Mechanical Stability

Compared to their high operating temperature counterparts such as high temperature protonic ceramic fuel cells or solid oxide fuel cells, solid acid fuel cells benefit from operating at low temperatures where plastic deformation and creep mechanisms are less likely to cause permanent damage to the cell materials. Permanent deformation occurs more readily at elevated temperatures because defects present within the material have sufficient energy to move and disrupt the original structure. Lower temperature operation also allows for the use of non-refractory materials which tends to decrease the cost of the SAFC.  

However, solid acid fuel cell electrolyte materials are still susceptible to mechanical degradation under normal operating conditions above their superprotonic phase transition temperatures due to the superplasticity enabled by this transition. [6] [27] [28] For instance in the case of CsHSO4, a study has shown that the material can undergo strain rates as high as for an applied compressive stress in the range of several MPa. Since fuel cells often require pressures in this range to properly seal the device and prevent leaks, creep is likely to degrade the cells by creating a short circuiting path. The same study showed that the strain rate, as modeled using the standard steady-state creep equation , has a stress exponent of  typically associated with a dislocation glide mechanism, and an activation energy of 1.02 eV. [27] n is the stress exponent, Q is the creep activation energy, and A is a constant that depends on the creep mechanism.

Creep resistance can be obtained by precipitate strengthening using a composite electrolyte whereby ceramic particles are introduced to prevent dislocation motion. For example, the strain rate of CsH2PO4 was reduced by a factor of 5 by mixing in SiO2 particles with a size of 2 microns, however resulting in a 20% decrease in protonic conductivity. [6]

Other studies have looked at CsH2PO4/epoxy resin composites where micron size particles of CsH2PO4 are embedded in a cross-linked polymer matrix. A comparison between the flexural strength of an SiO2 composite versus an epoxy composite demonstrated that while the strengths themselves are similar, the flexibility of the epoxy composite is superior, a property which is essential in preventing electrolyte fracture during operation. The epoxy composite also shows comparable but slightly lower conductivities than the SiO2 composite when operating at temperatures below 200 °C. [28]

Applications

Because of their moderate temperature requirements and compatibility with several types of fuel, SAFCs can be utilized in remote locations where other types of fuel cells would be impractical. In particular, SAFC systems for remote oil and gas applications have been deployed to electrify wellheads and eliminate the use of pneumatic components, which vent methane and other potent greenhouse gases straight into the atmosphere. [4] A smaller, portable SAFC system is in development for military applications that will run on standard logistic fuels, like marine diesel and JP8. [29]

In 2014, a toilet that chemically transforms waste into water and fertilizer was developed using a combination of solar power and SAFCs. [30]

Related Research Articles

<span class="mw-page-title-main">Fuel cell</span> Device that converts the chemical energy from a fuel into electricity

A fuel cell is an electrochemical cell that converts the chemical energy of a fuel and an oxidizing agent into electricity through a pair of redox reactions. Fuel cells are different from most batteries in requiring a continuous source of fuel and oxygen to sustain the chemical reaction, whereas in a battery the chemical energy usually comes from substances that are already present in the battery. Fuel cells can produce electricity continuously for as long as fuel and oxygen are supplied.

<span class="mw-page-title-main">Electrolysis</span> Technique in chemistry and manufacturing

In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity."

A regenerative fuel cell or reverse fuel cell (RFC) is a fuel cell run in reverse mode, which consumes electricity and chemical B to produce chemical A. By definition, the process of any fuel cell could be reversed. However, a given device is usually optimized for operating in one mode and may not be built in such a way that it can be operated backwards. Standard fuel cells operated backwards generally do not make very efficient systems unless they are purpose-built to do so as with high-pressure electrolysers, regenerative fuel cells, solid-oxide electrolyser cells and unitized regenerative fuel cells.

<span class="mw-page-title-main">Nafion</span> Brand name for a chemical product

Nafion is a brand name for a sulfonated tetrafluoroethylene based fluoropolymer-copolymer discovered in the late 1960s by Dr. Walther Grot of DuPont. Nafion is a brand of the Chemours company. It is the first of a class of synthetic polymers with ionic properties that are called ionomers. Nafion's unique ionic properties are a result of incorporating perfluorovinyl ether groups terminated with sulfonate groups onto a tetrafluoroethylene (PTFE) backbone. Nafion has received a considerable amount of attention as a proton conductor for proton exchange membrane (PEM) fuel cells because of its excellent chemical and mechanical stability in the harsh conditions of this application.

<span class="mw-page-title-main">Proton-exchange membrane fuel cell</span> Power generation technology

Proton-exchange membrane fuel cells (PEMFC), also known as polymer electrolyte membrane (PEM) fuel cells, are a type of fuel cell being developed mainly for transport applications, as well as for stationary fuel-cell applications and portable fuel-cell applications. Their distinguishing features include lower temperature/pressure ranges and a special proton-conducting polymer electrolyte membrane. PEMFCs generate electricity and operate on the opposite principle to PEM electrolysis, which consumes electricity. They are a leading candidate to replace the aging alkaline fuel-cell technology, which was used in the Space Shuttle.

<span class="mw-page-title-main">Solid oxide fuel cell</span> Fuel cell that produces electricity by oxidization

A solid oxide fuel cell is an electrochemical conversion device that produces electricity directly from oxidizing a fuel. Fuel cells are characterized by their electrolyte material; the SOFC has a solid oxide or ceramic electrolyte.

<span class="mw-page-title-main">Alkaline fuel cell</span> Type of fuel cell

The alkaline fuel cell (AFC), also known as the Bacon fuel cell after its British inventor, Francis Thomas Bacon, is one of the most developed fuel cell technologies. Alkaline fuel cells consume hydrogen and pure oxygen, to produce potable water, heat, and electricity. They are among the most efficient fuel cells, having the potential to reach 70%.

A proton-exchange membrane, or polymer-electrolyte membrane (PEM), is a semipermeable membrane generally made from ionomers and designed to conduct protons while acting as an electronic insulator and reactant barrier, e.g. to oxygen and hydrogen gas. This is their essential function when incorporated into a membrane electrode assembly (MEA) of a proton-exchange membrane fuel cell or of a proton-exchange membrane electrolyser: separation of reactants and transport of protons while blocking a direct electronic pathway through the membrane.

<span class="mw-page-title-main">Electrolysis of water</span> Electricity-induced chemical reaction

Electrolysis of water is using electricity to split water into oxygen and hydrogen gas by electrolysis. Hydrogen gas released in this way can be used as hydrogen fuel, but must be kept apart from the oxygen as the mixture would be extremely explosive. Separately pressurised into convenient 'tanks' or 'gas bottles', hydrogen can be used for oxyhydrogen welding and other applications, as the hydrogen / oxygen flame can reach approximately 2,800°C.

<span class="mw-page-title-main">Protonic ceramic fuel cell</span>

A protonic ceramic fuel cell or PCFC is a fuel cell based around a ceramic, solid, electrolyte material as the proton conductor from anode to cathode. These fuel cells produce electricity by removing an electron from a hydrogen atom, pushing the charged hydrogen atom through the ceramic membrane, and returning the electron to the hydrogen on the other side of the ceramic membrane during a reaction with oxygen. The reaction of many proposed fuels in PCFCs produce electricity and heat, the latter keeping the device at a suitable temperature. Efficient proton conductivity through most discovered ceramic electrolyte materials require elevated operational temperatures around 600-700 degrees Celsius, however intermediate temperature (200-400 degrees Celsius) ceramic fuel cells and lower temperature alternative are an active area of research. In addition to hydrogen gas, the ability to operate at intermediate and high temperatures enables the use of a variety of liquid hydrogen carrier fuels, including: ammonia, and methane. The technology shares the thermal and kinetic advantages of high temperature molten carbonate and solid oxide fuel cells, while exhibiting all of the intrinsic benefits of proton conduction in proton-exchange membrane fuel cells (PEMFC) and phosphoric acid fuel cells (PAFC). PCFCs exhaust water at the cathode and unused fuel, fuel reactant products and fuel impurities at the anode. Common chemical compositions of the ceramic membranes are barium zirconate (BaZrO3), barium cerate (BaCeO3), caesium dihydrogen phosphate (CsH2PO4), and complex solid solutions of those materials with other ceramic oxides. The acidic oxide ceramics are sometimes broken into their own class of protonic ceramic fuel cells termed "solid acid fuel cells".

Gas diffusion electrodes (GDE) are electrodes with a conjunction of a solid, liquid and gaseous interface, and an electrical conducting catalyst supporting an electrochemical reaction between the liquid and the gaseous phase.

The Glossary of fuel cell terms lists the definitions of many terms used within the fuel cell industry. The terms in this fuel cell glossary may be used by fuel cell industry associations, in education material and fuel cell codes and standards to name but a few.

Sossina M. Haile is an American chemist, known for developing the first solid acid fuel cells. She is a professor of materials science and engineering at Northwestern University, Illinois, US.

<span class="mw-page-title-main">Alkaline anion-exchange membrane fuel cell</span>

An alkaline anion-exchange membrane fuel cell (AAEMFC), also known as anion-exchange membrane fuel cells (AEMFCs), alkaline membrane fuel cells (AMFCs), hydroxide-exchange membrane fuel cells (HEMFCs), or solid alkaline fuel cells (SAFCs) is a type of alkaline fuel cell that uses an anion-exchange membrane to separate the anode and cathode compartments.

<span class="mw-page-title-main">Proton exchange membrane electrolysis</span> Technology for splitting water molecules

Proton exchange membrane(PEM) electrolysis is the electrolysis of water in a cell equipped with a solid polymer electrolyte (SPE) that is responsible for the conduction of protons, separation of product gases, and electrical insulation of the electrodes. The PEM electrolyzer was introduced to overcome the issues of partial load, low current density, and low pressure operation currently plaguing the alkaline electrolyzer. It involves a proton-exchange membrane.

Solid acids are acids that are insoluble in the reaction medium. They are often used as heterogeneous catalysts.

<span class="mw-page-title-main">Caesium bisulfate</span> Chemical compound

Caesium bisulfate or cesium hydrogen sulfate is an inorganic compound with the formula CsHSO4. The caesium salt of bisulfate, it is a colorless solid obtained by combining Cs2SO4 and H2SO4.

High Temperature Proton Exchange Membrane fuel cells (HT-PEMFC), also known as High Temperature Polymer Electrolyte Membrane fuel cells, are a type of PEM fuel cells which can be operated at temperatures between 120 and 200°C. HT-PEM fuel cells are used for both stationary and portable applications. The HT-PEM fuel cell is usually supplied with hydrogen-rich gas like reformate gas formed by reforming of methanol, ethanol, natural gas or LPG.

The Iron Redox Flow Battery (IRFB), also known as Iron Salt Battery (ISB), stores and releases energy through the electrochemical reaction of iron salt. This type of battery belongs to the class of redox-flow batteries (RFB), which are alternative solutions to Lithium-Ion Batteries (LIB) for stationary applications. The IRFB can achieve up to 70% round trip energy efficiency. In comparison, other long duration storage technologies such as pumped hydro energy storage provide around 80% round trip energy efficiency.

References

  1. 1 2 3 Calum R.I. Chisholm, Dane A. Boysen, Alex B. Papandrew, Strahinja Zecevic, SukYal Cha, Kenji A. Sasaki, Áron Varga, Konstantinos P. Giapis, Sossina M. Haile. "From Laboratory Breakthrough to Technological Realization: The Development Path for Solid Acid Fuel Cells." The Electrochemical Society Interface Vol 18. No 3. (2009).
  2. ↑ Papandrew, Alexander B.; Chisholm, Calum R.I.; Elgammal, Ramez A.; Özer, Mustafa M.; Zecevic, Strahinja K. (2011-04-12). "Advanced Electrodes for Solid Acid Fuel Cells by Platinum Deposition on CsH2PO4" (PDF). Chemistry of Materials. 23 (7): 1659–1667. doi:10.1021/cm101147y. ISSN   0897-4756.
  3. 1 2 Sossina M. Haile, Dane A. Boysen, Calum R. I. Chisholm, Ryan B. Merle. "Solid acids as fuel cell electrolytes." Nature 410, 910-913 (19 April 2001). doi:10.1038/35073536.
  4. 1 2 “SAFCell – Oil and Gas.” http://www.safcell.com/oil-gas/
  5. ↑ Ryan B. Merle, Calum R. I. Chisholm, Dane A. Boysen, Sossina M. Haile. "Instability of Sulfate and Selenate Solid Acids in Fuel Cell Environments." Energy Fuels, 2003, 17 (1), pp 210–215. DOI: 10.1021/ef0201174
  6. 1 2 3 Sossina M. Haile, Calum R. I. Chisholm, Kenji Sasaki, Dane A. Boysen, Tetsuya Uda. "Solid acid proton conductors: from laboratory curiosities to fuel cell electrolytes." Faraday Discuss., 2007, 134, 17-39. DOI: 10.1039/B604311A
  7. ↑ Baranov, A. I.; Khiznichenko, V. P.; Sandler, V. A.; Shuvalov, L. A. (1988-05-01). "Frequency dielectric dispersion in the ferroelectric and superionic phases of CsH2PO4". Ferroelectrics. 81 (1): 183–186. Bibcode:1988Fer....81..183B. doi:10.1080/00150198808008840. ISSN   0015-0193.
  8. ↑ Baranov, A. I.; Khiznichenko, V. P.; Shuvalov, L. A. (1989-12-01). "High temperature phase transitions and proton conductivity in some kdp-family crystals". Ferroelectrics. 100 (1): 135–141. Bibcode:1989Fer...100..135B. doi:10.1080/00150198908007907. ISSN   0015-0193.
  9. ↑ Baranov, A. I.; Merinov, B. V.; Tregubchenko, A. V.; Khiznichenko, V. P.; Shuvalov, L. A.; Schagina, N. M. (1989-11-01). "Fast proton transport in crystals with a dynamically disordered hydrogen bond network". Solid State Ionics. 36 (3): 279–282. doi:10.1016/0167-2738(89)90191-4.
  10. ↑ Otomo, Junichiro; Tamaki, Takanori; Nishida, Satoru; Wang, Shuqiang; Ogura, Masaru; Kobayashi, Takeshi; Wen, Ching-ju; Nagamoto, Hidetoshi; Takahashi, Hiroshi (2005). "Effect of water vapor on proton conduction of cesium dihydrogen phosphateand application to intermediate temperature fuel cells". Journal of Applied Electrochemistry. 35 (9): 865–870. doi:10.1007/s10800-005-4727-4. ISSN   0021-891X. S2CID   96019963.
  11. ↑ Boysen, Dane A.; Uda, Tetsuya; Chisholm, Calum R. I.; Haile, Sossina M. (2004-01-02). "High-Performance Solid Acid Fuel Cells Through Humidity Stabilization" (PDF). Science. 303 (5654): 68–70. Bibcode:2004Sci...303...68B. doi:10.1126/science.1090920. ISSN   0036-8075. PMID   14631049. S2CID   10829089.
  12. ↑ Cheap Diesel-Powered Fuel Cells. Bullis, Kevin. October 21, 2010. MIT Technology Review.
  13. ↑ Diesel: The Fuel of the Future? February 11, 2013. Discovery News.
  14. ↑ Running fuel cells on biodiesel. Claude R. Olsen, Else Lie. October 8, 2010. The Research Council of Norway.
  15. ↑ Uda, Tetsuya; Haile, Sossina M. (2005-05-01). "Thin-Membrane Solid-Acid Fuel Cell" (PDF). Electrochemical and Solid-State Letters. 8 (5): A245–A246. doi:10.1149/1.1883874. ISSN   1099-0062.
  16. ↑ Suryaprakash, R. C.; Lohmann, F. P.; Wagner, M.; Abel, B.; Varga, A. (2014-11-10). "Spray drying as a novel and scalable fabrication method for nanostructured CsH2PO4, Pt-thin-film composite electrodes for solid acid fuel cells". RSC Advances. 4 (104): 60429–60436. Bibcode:2014RSCAd...460429S. doi:10.1039/C4RA10259B. ISSN   2046-2069.
  17. ↑ Lohmann, F. P.; Schulze, P. S. C.; Wagner, M.; Naumov, O.; Lotnyk, A.; Abel, B.; Varga, Á. (2017). "The next generation solid acid fuel cell electrodes: stable, high performance with minimized catalyst loading". Journal of Materials Chemistry A. 5 (29): 15021–15025. doi:10.1039/c7ta03690f. ISSN   2050-7488.
  18. ↑ Papandrew, Alexander B.; John, Samuel St.; Elgammal, Ramez A.; Wilson, David L.; Atkinson, Robert W.; Lawton, Jamie S.; Arruda, Thomas M.; Zawodzinski, Thomas A. (2016). "Vapor-Deposited Pt and Pd-Pt Catalysts for Solid Acid Fuel Cells: Short Range Structure and Interactions with the CsH2PO4Electrolyte". Journal of the Electrochemical Society. 163 (6): F464–F469. doi: 10.1149/2.0371606jes . ISSN   0013-4651. S2CID   100764488.
  19. ↑ Monzó, J.; Vliet, D. F. van der; Yanson, A.; Rodriguez, P. (2016-08-10). "Elucidating the degradation mechanism of the cathode catalyst of PEFCs by a combination of electrochemical methods and X-ray fluorescence spectroscopy". Physical Chemistry Chemical Physics. 18 (32): 22407–22415. Bibcode:2016PCCP...1822407M. doi:10.1039/C6CP03795J. ISSN   1463-9084. PMID   27464340. S2CID   38976147.
  20. ↑ Zhang, Shengsheng; Yuan, Xiao-Zi; Hin, Jason Ng Cheng; Wang, Haijiang; Friedrich, K. Andreas; Schulze, Mathias (December 2009). "A review of platinum-based catalyst layer degradation in proton exchange membrane fuel cells". Journal of Power Sources. 194 (2): 588–600. Bibcode:2009JPS...194..588Z. doi:10.1016/j.jpowsour.2009.06.073.
  21. ↑ Thoi, V. Sara; Usiskin, Robert E.; Haile, Sossina M. (2015). "Platinum-decorated carbon nanotubes for hydrogen oxidation and proton reduction in solid acid electrochemical cells". Chemical Science. 6 (2): 1570–1577. doi:10.1039/c4sc03003f. ISSN   2041-6520. PMC   5811139 . PMID   29560244.
  22. ↑ Wang, Cheng; Waje, Mahesh; Wang, Xin; Tang, Jason M.; Haddon, Robert C.; Yan (2003-12-30). "Proton Exchange Membrane Fuel Cells with Carbon Nanotube Based Electrodes". Nano Letters. 4 (2): 345–348. doi:10.1021/nl034952p. ISSN   1530-6984.
  23. ↑ Liu, Chueh; Wang, Chih‐Chieh; Kei, Chi‐Chung; Hsueh, Yang‐Chih; Perng, Tsong‐Pyng (2009-06-30). "Atomic Layer Deposition of Platinum Nanoparticles on Carbon Nanotubes for Application in Proton‐Exchange Membrane Fuel Cells". Small. 5 (13): 1535–1538. doi:10.1002/smll.200900278. ISSN   1613-6810. PMID   19384876.
  24. ↑ Vijayaraghavan, Ganesh; Stevenson, Keith J. (2008-05-27). "Chemical Vapor Deposition of Nanocarbon-Supported Platinum and Palladium Catalysts for Oxygen Reduction". ECS Transactions. 6 (25): 43–50. Bibcode:2008ECSTr...6y..43V. doi:10.1149/1.2943223. ISSN   1938-5862. S2CID   100769294.
  25. ↑ Sossina M. Haile, Calum R. I. Chisholm, Kenji Sasaki, Dane A. Boysen, Tetsuya Uda. "Solid acid proton conductors: from laboratory curiosities to fuel cell electrolytes." Faraday Discuss., 2007, 134, 17-39. DOI: 10.1039/B604311A
  26. ↑ Wagner, Maximilian; Lorenz, Oliver; Lohmann-Richters, Felix P.; Varga, Áron; Abel, Bernd (2021). "Study on solid electrolyte catalyst poisoning in solid acid fuel cells". Journal of Materials Chemistry A. 9 (18): 11347–11358. doi:10.1039/D1TA01002F. ISSN   2050-7488. S2CID   234910940.
  27. 1 2 Ginder, Ryan S.; Pharr, George M. (October 2017). "Creep behavior of the solid acid fuel cell material CsHSO4". Scripta Materialia. 139: 119–121. doi: 10.1016/j.scriptamat.2017.06.019 .
  28. 1 2 Qing, Geletu; Kikuchi, Ryuji; Takagaki, Atsushi; Sugawara, Takashi; Oyama, Shigeo Ted (July 2015). "CsH2PO4/Epoxy Composite Electrolytes for Intermediate Temperature Fuel Cells". Electrochimica Acta. 169: 219–226. doi:10.1016/j.electacta.2015.04.089.
  29. ↑ SAFCell Inc. awarded Enhancement grant from US Army. Pasadena, California. SAFCell, Inc. May 16, 2016. http://www.ultracell-llc.com/assets/UltraCell_BT-press-release-17-May-2016-FINAL.pdf
  30. ↑ Solar/Fuel Cell-Powered Caltech-Designed Enviro-Toilet to Debut in India. Pasadena, California. The Hydrogen and Fuel Cell Letter. February 2014. http://www.hfcletter.com/Content/EnviroToilet.aspx
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