Coordination polymer glass from a protic ionic liquid: proton conductivity and mechanical properties as an electrolyte

High proton conducting electrolytes with mechanical moldability are a key material for energy devices. We propose an approach for creating a coordination polymer (CP) glass from a protic ionic liquid for a solid-state anhydrous proton conductor. A protic ionic liquid (dema)(H2PO4), with components which also act as bridging ligands, was applied to construct a CP glass (dema)(0.35)[Zn(H2PO4)(2.35)(H3PO4)(0.65)]. The structural analysis revealed that large Zn-H2PO4-/H3PO4 coordination networks formed in the CP glass. The network formation results in enhancement of the properties of proton conductivity and viscoelasticity. High anhydrous proton conductivity ( s = 13.3 mS cm(-1) at 120 degrees C) and a high transport number of the proton (0.94) were achieved by the coordination networks. A fuel cell with this CP glass membrane exhibits a high open-circuit voltage and power density (0.15 W cm(-2)) under dry conditions at 120 degrees C due to the conducting properties and mechanical properties of the CP glass.