Fuel Cell

A fuel cell is a device, which chemically oxidizes its fuel, usually hydrogen from hydrocarbons that have been reprocessed into hydrogen and carbon monoxide in the absence of a flame, generating heat and electricity. Modern fuel cells may be divided into low, medium and high temperature:

 

Proton Exchange Membrane Fuel Cells (PEM) and Direct Methanol Fuel Cells (DMFC) utilize graphite products in several parts – graphite powders are used in carbon-based bipolar plates, in gas diffusion layers and catalyst supports, while graphite dispersions can be applied to metal-based bipolar plates and to gas diffusion layers. In particular, graphite foils, machined and assembled, creates basic substrates for ultra-light and thin bipolar plates while graphite is included in thermoplastics, thermosets, and electronically conducting polymers used to manufacture the bipolar plate. At the same time, graphite has a relatively high specific BET surface area because of their mesoporous graphite structure, which combined with its electrical conductivity and purity, allows it to be used for metal catalyst supports in the electrode assembly. The isometric particle shape and bulk density result in excellent electrode performance and also make the electrode manufacturing process easier. Graphite can be used as substrates in gas diffusion layers because of the porosity, high tap density, and electrical conductivity.

As with the battery information, the table on the preceding page also includes a description of a number of the benefits, characteristics and specifications of natural graphite in these fuel cells.

Bipolar Plates are one key component in various fuel cell systems specifically PEM (proton-exchange membrane) fuel cells. The bipolar plate performs basic functions int he fuel cell stack operation:

• good electrical conductivity
• high thermal conductivity
• high chemical and corrosion resistance
• mechanical stability
• low permeability for hydrogen
• low cost material