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.