Unitized Regenerative Fuel Cell Performance Using Polymer Wicks for Passive Water Management

Proton Exchange Membrane (PEM) fuel cells rely on effective internal water transport to provide stable performance. Many water management schemes require high heat, high pressure, or high flow rates — effectively introducing parasitic losses and reducing round-trip efficiency. In this work, a radial, non-recirculating, unitized regenerative fuel cell prototype with passive water transport is designed and tested. The cell features a 5 cm² active area with 1.2 mm wide by 0.6 mm high gas flow channels. Porous polymer wicks are fabricated in the cathode side flow channels and coupled with a bulk water storage structure. The resulting wicks are 0.3 mm wide and 0.6 mm high. Discharge operating voltage measured during current control testing resulted in 1 V at open circuit, 0.8 V at 0.3 A·cm⁻², and 0.2 V at 1 A·cm⁻². Charge operating current density measured during voltage control testing resulted in 0.1 A·cm⁻² at 1.5 V, 0.3 A·cm⁻² at 1.6 V, and 0.8 A·cm⁻² at 2 V. During the membrane electrode assembly (MEA) conditioning procedure, degradation in operating current density is seen over a 30–100 minute time span.