Formic acid fuel cell
Encyclopedia
Direct-formic acid fuel cells or DFAFCs are a subcategory of proton exchange membrane fuel cell
Proton exchange membrane fuel cell
Proton exchange membrane fuel cells, also known as polymer electrolyte membrane fuel cells , are a type of fuel cell being developed for transport applications as well as for stationary fuel cell applications and portable fuel cell applications. Their distinguishing features include lower...

s where, the fuel, formic acid, is not reformed, but fed directly to the fuel cell. Their applications include small, portable electronics such as phones and laptop computers.

Advantages

Similar to methanol
Methanol
Methanol, also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits, is a chemical with the formula CH3OH . It is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to, but slightly sweeter than, ethanol...

, formic acid
Formic acid
Formic acid is the simplest carboxylic acid. Its chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in the venom of bee and ant stings. In fact, its name comes from the Latin word for ant, formica, referring to its early...

 is a small organic molecule fed directly into the fuel cell, removing the need for complicated catalytic reforming
Catalytic reforming
Catalytic reforming is a chemical process used to convert petroleum refinery naphthas, typically having low octane ratings, into high-octane liquid products called reformates which are components of high-octane gasoline...

. Storage of formic acid is much easier and safer than that of hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 because it does not need to be done at high pressures and (or) low temperatures, as formic acid is a liquid at standard temperature and pressure. Formic acid does not cross over the polymer membrane, so its efficiency can be higher than that of methanol.

Reactions

DFAFCs convert formic acid and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 into carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 and water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 to produce energy. Formic acid oxiation occurs at the anode
Anode
An anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID ....

 on a catalyst layer. Carbon dioxide is formed and protons (H+) are passed through the polymer membrane to react with oxygen on a catalyst layer located at the cathode
Cathode
A cathode is an electrode through which electric current flows out of a polarized electrical device. Mnemonic: CCD .Cathode polarity is not always negative...

. Electrons are passed through an external circuit from anode to cathode to provide power to an external device.

Anode: HCOOH → CO2 + 2 H+ + 2 e-

Cathode: 1/2 O2 + 2 H+ + 2 e- → H2O

Net reaction: HCOOH + 1/2 O2 → CO2 + H2O

History

During previous investigations, researchers dismissed formic acid as a practical fuel because of the high overpotential
Overpotential
Overpotential is an electrochemical term which refers to the potential difference between a half-reaction's thermodynamically determined reduction potential and the potential at which the redox event is experimentally observed. The term is directly related to a cell's voltage efficiency...

 shown by experiments: this meant the reaction appeared to be too difficult to be practical. However, in 2005- 2006, other researchers (in particular Richard Masel's group at the University of Illinois at Urbana-Champaign
University of Illinois at Urbana-Champaign
The University of Illinois at Urbana–Champaign is a large public research-intensive university in the state of Illinois, United States. It is the flagship campus of the University of Illinois system...

) found that the reason for the low performance was the usage of platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...

 as a catalyst, as it is common in most other types of fuel cells: using palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...

 instead, they claim to have obtained better performance than equivalent direct methanol fuel cells.
Tekion holds the exclusive license to formic-acid fuel cell technology from the University of Illinois at Urbana-Champaign. The company now is focusing on developing a miniature hybrid battery/fuel-cell unit called the Formira Power Pack and hopes to introduce the packs in the fourth quarter of 2007. The Power Packs rely on the fuel cell, instead of a conventional electrical source like a wall outlet, to recharge the batteries. When the fuel is exhausted, users simply replace the empty fuel cartridge with a fresh one. Because of the high power density of the fuel cell, it should provide about double the time between charges. This technology is expected to only cost about 10-15% more than traditional batteries.

See also

  • Glossary of fuel cell terms
    Glossary of fuel cell terms
    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. –...

  • Portable fuel cell applications
    Portable fuel cell applications
    Fuel cell applications are stationary fuel cell applications and portable fuel cell plications...

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