Background: This graphene-based proton exchange membrane improves direct methanol fuel cells\\\' performance. Because methanol has a high energy density and is easy to store direct methanol fuel cells (DMFCs) could become viable energy sources for portable applications enabling users to charge notebook computers mobile phones vehicles and military or medical equipment when wall plugs are inaccessible. The proton exchange membranes (PEMs) now found in DMFCs experience excessive swelling at high fuel concentrations and allow for undesirable fuel crossover. By using graphene as a starting material University of Florida researchers created a PEM layer that is highly selective to proton transport. PEMs made from graphene survive concentrated methanol solutions without swelling. Sufficiently large platelets suppress methanol crossover improving PEM stability and resulting in direct methanol fuel cells with higher power density and higher energy output. This new proton exchange membrane will simplify DMFCs fabrication removing a barrier to widespread adoption. The market for DMFCs is expected to grow 45 percent a year until 2016 when annual revenue will reach approximately $109 million. Technology Description: University of Florida researchers have developed a graphene-based proton exchange membrane that addresses the problems of excessive swelling at high fuel concentrations and undesirable fuel crossover. It boasts three orders of magnitude lower methanol diffusion coefficient and two orders of magnitude higher proton selectivity compared to Nafion. At high fuel concentrations the membrane also outperforms Nafion by showing almost no drop in open circuit potential (OCP) and a 120 percent increase in power density at 10 M methanol. The membrane does not exhibit swelling and mechanical failure at high methanol concentrations and under significant electro-osmotic drag. Applications: Graphene-based proton exchange membrane that creates more efficient direct methanol fuel cells for better-performing electronic devices.
1) Allows for the creation of DMFCs with improved energy output and power density providing a competitive advantage over available direct methanol fuel cells 2) Prevents swelling at higher temperatures improving performance and durability 3) Functions better in highly concentrated methanol solutions than existing PEMs enhancing reliability 4) Represents an essential advancement in PEMs removing a barrier to widespread commercialization of DMFCsve (relating SERS signal intensity to heavy metal ion concentration).