Metal Oxide-Based Materials for Flexible and Portable Fuel Cells: Current Status and Future Prospects

Fuel cells are being explored as a convenient and long-lasting power source for various applications. With the increasing popularity of portable consumer electronics like smartphones and other handheld devices, significant efforts have been made in the past decade to develop flexible fuel cells to serve the demands of the portable applications sector. Low-temperature fuel cells, especially polymer electrolyte membrane fuel cells (PEMFC) and direct liquid fuel cells, employ mature membrane electrolyte technology and offer promising prospects for portable power sources. Traditionally, fuel cells utilize inflexible materials based on metal or carbon frameworks, such as graphitic bipolar plates, which may be suitable for stationary and transportation applications but would be less favorable for portable applications. In this regard, metal oxide-based systems are being investigated as more flexible substrates, as well as for catalysts, supports, additives in the membrane, etc., to exploit various beneficial physical and electrochemical properties. This chapter provides a concise overview of the current status regarding the strategic use of metal oxide-based systems for various components in flexible fuel cells. It also discusses the future prospects and directions to further develop flexible and portable fuel cells for commercial applications.