FOCUS ON MATERIALS
By
Stefan Lindner ,
Lead Technical Manager , Outokumpu Oy .
Hydrogen is gaining rapid momentum as the ‘ fuel of the future .’ According to some estimates , Europe ’ s hydrogen economy is already worth around € 2 billion , with predictions that it could grow to € 140- billion by 2030 ( source : Pangea Strategic Intelligence ).
A critical element in the success of the hydrogen economy will be electric vehicles ( EVs ), powered by fuel cells . This means that fuel cell design and manufacturing must be adapted for cost-effective mass production . That is where stainless steel offers particular promise . It is ideal for pressing and welding the very thin bipolar plates that are a critical element in the low-temperature Polymer Electrolyte Membrane ( PEM ) fuel cells which are typically used in EVs .
PEM fuel cells
A fuel cell is simply a device that enables the well-known electrochemical process of electrolysis to happen in reverse . In electrolysis , a current is passed through liquid water ( H 2
O ), causing it to break down into hydrogen ( H 2
) and oxygen ( O 2 ) gas . In contrast , the fuel cell causes H 2 and O 2 gases to react together . This produces a current , with water as the harmless byproduct .
A PRESSING PERFORMANCE
Stefan Lindner , lead technical manager for Outokumpu , explains why thin stainless-steel foil offers particular benefits for mass production of the bipolar plates at the heart of fuel cell stacks .
Many different types of fuel cell have been designed to operate at a range of temperatures . Low-temperature designs , operating at around 70 to 90 º C , are of most interest for EVs . One of the most promising types is the PEM fuel cell . This design offers the benefits of higher power density
A critical element in the success of the hydrogen economy will be electric vehicles ( EVs ), powered by fuel cells
“ Stainless steel is ideal for pressing and welding the very thin bipolar plates used in PEM fuel cells for electric vehicles .”
( 1kW / kg ) and flexible performance at a lower cost per unit power (€/ W ) in a compact , lightweight package .
One of the most critical elements in the construction of a PEM fuel cell are the bipolar plates – see Figure 1 below .
The bipolar plates provide a passageway for transporting the H 2 gas to the anode and the
O 2 gas to the cathode , bringing them into close proximity ( separated only by the electrolyte membrane ) so that they can react with each other . In a transportation fuel cell , the membrane is very thin , sometimes only around 20 microns . The plates must also enable the current produced to be transported from the fuel cell , as well as managing the water and
Figure 1 : Bipolar plates are the fundamental elements in the PEM fuel cell .
28 | sheetmetalplus . com | ISMR February 2022