A novel cathode gas diffusion layer for water management of passive μ-DMFC

Micro Direct Methanol Fuel Cell (μDMFC) has been a promising new type of portable energy device due to its high energy density, quick start features and simple operation environment. Water management is one of the most crucial problems for hindering the development of passive μDMFC. A novel cathode structure of passive μDMFC controlling water management and increasing methanol concentration is proposed and fabricated. The reduced graphene oxide deposited in stainless steel fiber felt (SSFF) as gas diffusion layer (GDL) and cathode electrode plate enhances water back diffusion which passively prevents water flooding in the cathode and promotes low methanol crossover in the anode at the same time. Contact angle indicates that the composite structure has a hydrophilic contact angle, spreading water adhering on it rapidly. The passive μDMFC with novel cathode structure exhibits significantly higher performance than traditional μDMFC, especially in high concentration, with peak power density of 23.8 mW cm−2 at 3 M at room temperature. EIS (electrochemical impedance spectroscopy, EIS) test results show that the novel structure helps reduce the internal resistance. The power density at 4 M and 5 M of novel μDMFC is distinctly higher than that of the conventional, which demonstrates that the novel μDMFC with novel cathode gas diffusion layer has a higher performance than the traditional one, especially at high concentration.