Tubular polymer electrolyte membrane fuel cell stack

A fuel cell stack with a tubular polymer electrolyte membrane, the fuel cell stack comprising:

• a plurality of fuel cell units having a truncated cone shape and connected in series, the plurality of fuel cell units comprising at least a first fuel cell unit and a second fuel cell unit adjacent to each other,
• wherein a relatively small outer diameter portion of the first fuel cell unit is inserted into a relatively large outer diameter portion of the second fuel cell unit,
• wherein each of the first and second fuel cell units comprises:
• a truncated cone-shaped current collector layer,
• an anode diffusion layer wound around the current collector layer to absorb gas or liquid to be supplied to an anode electrode,
• a membrane electrode assembly layer wound around the anode diffusion layer, comprising an electrolyte membrane, an anode electrode, and a cathode electrode, and configured such that gas or liquid supplied from the anode diffusion layer ionizes at the anode electrode and the resulting ions move to the cathode electrode through the electrolyte membrane, and
• a cathode diffusion layer wound around the membrane electrode assembly to absorb gas or liquid that is configured to chemically react with the ions supplied to the cathode electrode through the electrolyte membrane,
• wherein:
• the anode diffusion layer is wound within a predetermined region of the current collector layer, the predetermined region being positioned in a range from a first side having a relatively small outer diameter to a second side having a relatively large outer diameter, of both sides of the current collector layer,
• the membrane electrode assembly layer is wound over an extended range that includes the entire region of the anode diffusion layer,
• the cathode diffusion layer is wound within a predetermined region of the membrane electrode assembly layer, the predetermined region spaced from both sides of the membrane electrode assembly layer,
• the anode diffusion layer is wound around an upper portion of the second fuel cell unit having a smaller diameter than a lower portion of the second fuel cell unit, the cathode diffusion layer is wound over and covers the anode diffusion layer,
• the cathode diffusion layer along with the upper portion of the second fuel cell unit covered by the cathode diffusion layer is inserted into the first fuel cell unit such that the anode and cathode diffusion layers of the second fuel cell unit are radially compressed in the assembled state, the resulting gap between the current collector layers of the first and second fuel cell units being smaller than the combined uncompressed thicknesses of the anode and cathode diffusion layers of the second fuel cell unit, so as to reduce electrical contact resistance between the current collector layers of the first and second fuel cell units, and
• no separate clamping member or end plate is used to maintain the compression or electrical contact.