A passive microfluidic hydrogen-air fuel cell with exceptional stability and high performance

Area of Science:

• Electrochemistry
• Materials Science
• Chemical Engineering

Background:

• Microfluidic fuel cells (FCs) offer miniaturized power solutions but often face challenges with durability and complex fluid management.
• Conventional designs rely on external pumps and separator membranes, limiting their passive operation and long-term stability.
• Developing membrane-less, passively operated microfluidic FCs with high performance is crucial for portable electronics and distributed power generation.

Purpose of the Study:

• To develop and characterize an advanced, membrane-less microfluidic hydrogen-air fuel cell (FC) with exceptional durability and high performance.
• To investigate the influence of electrolyte composition and anode material on the operational stability and power output of the passive FC.
• To demonstrate the potential of this novel FC architecture for powering portable electronic devices.

Main Methods:

• Fabrication of a poly(dimethylsiloxane) (PDMS)-based microfluidic network housing high surface area metal and metal alloy electrodes.
• Immersive electrode design within a liquid electrolyte, enabling passive reagent supply via gas permeation through the PDMS network.
• Systematic evaluation of different anode materials (Pt, Pd, Pd/Pt) and electrolytes (5 M H2SO4, 2.5 M NaOH) to determine optimal performance and stability.

Main Results:

• Stable power output exceeding 100 days was achieved without an anode-cathode separator membrane, showcasing exceptional durability.
• The fuel cell demonstrated high performance, particularly when utilizing a palladium adlayer on a porous platinum electrode (Pd/Pt) in a 5 M H2SO4 electrolyte.
• The passive device architecture, relying on gas permeation through PDMS and optimized anode selectivity, effectively managed reagent flow and minimized performance degradation.

Conclusions:

• The developed membrane-less, passive microfluidic hydrogen-air fuel cell offers a promising pathway towards highly durable and efficient portable power sources.
• The choice of electrolyte and anode material significantly impacts operational stability, with the Pd/Pt anode in acidic electrolyte showing superior performance.
• The intrinsic properties of the PDMS network, combined with optimized electrode design, facilitate long-term operation and mitigate issues like carbonate formation.