(304b) Materials and Cell Designs for Bipolar Fuel Cells

Anionic fuel cells are a possible route to overcoming fundamental issues with acid-based fuel cells. The issues include the high cost of platinum catalysts, complex water transport, and sluggish electrochemical reactions. In particular, a bipolar membrane composed of a cation conducting material and an anion conducting material has several additional advantages because each electrode can have an optimum pH, and water can be created at the cation/anion membrane interface close to where it is used at the air cathode.

Material transport properties play an important role in determining viability of membrane and ionomer materials. Additionally, the material at the cation/anion junction is critical to device performance, as it must conduct ions to the interface in addition to mechanically binding the membranes. A series of devices using different interfacial materials has been fabricated for use in direct methanol and hydrogen fuel cells. These fuel cells were characterized by performance metrics and electroimpedance spectroscopy to determine specific areas for improvement in the bipolar devices. Operation under varying humidity was studied in order to understand water management necessary for bipolar fuel cells. This work will drive the future optimization of bipolar devices.