Ordered Proton Transport Channels in a Layered Host–Guest Crystal for High-Performance Fuel Cells

Developing solid electrolytes with high intrinsic proton conductivity over a broad temperature range is crucial for proton exchange membrane fuel cells. We report a new layered cadmium chlorophosphate crystal, (C 3 N 2 H 5 )[CdCl(H 3/2 PO 4 )] 2 (CdClPO 4 -ImH), featuring highly ordered one-dimensional proton transport channels formed by host–guest synergy between imidazolium cations and inorganic layers. Structural and theoretical analyses revealed a continuous hydrogen-bonding network that promotes efficient proton hopping. The material shows excellent proton conductivity from −20 to 90 °C, reaching 2.57 × 10 –2 S cm –1 at 90 °C and 95% relative humidity (RH). An undoped intrinsic membrane delivered a peak power density of 104 mW cm –2 in a H 2 /O 2 fuel cell.