Simultaneous mapping of temperature and hydration in proton-exchange membranes of fuel cells using magnetic resonance imaging

The efficiency of a proton-exchange membrane (PEM) fuel cell depends on the mobility of protons in PEMs, which in turn is determined by the hydration and temperature of the membrane. Spin-lattice relaxation time (T1) and spin-spin relaxation time (T2) contrast magnetic resonance imaging may be used to map hydration in PEMs under isothermal conditions, but not when there are thermal gradients in PEMs. In this work, we show that a combination of chemical shift and diffusion imaging can decouple and map temperature and hydration in PEMs. We demonstrate a 16 × 16 pixel magnetic resonance imaging mapping of hydration and temperature in Nafion PEMs with a spatial resolution of 1 × 1 mm and a total scan time of 3 min, with uncertainty in hydration and temperature of 15% and 6 K, respectively. The method can be generalized for exchange membranes of any flow batteries.