Phosphoric acid-imbibed three-dimensional polyacrylamide/poly(vinyl alcohol) hydrogel as a new class of high-temperature proton exchange membrane

This paper reports the first study that investigates H3PO4-imbibed polyacrylamide/poly(vinyl alcohol) (PAM/PVA) semi-interpenetrating polymer network (semi-IPN) hydrogel as a high-temperature proton exchange membrane (PEM). The extraordinary ability of the PAM/PVA hydrogel to absorb a large quantity of aqueous solution is fully utilized to achieve a high H3PO4 loading, resulting in high proton conductivity membranes. The anhydrous proton conductivity of a PAM/PVA semi-IPN hydrogel loaded with 73.5 wt% H3PO4 reaches 0.0525 S cm−1 at 183 °C in dry air. A fuel cell using the thick-film PAM/PVA hydrogel exhibits a peak power density of 0.225 W cm−2 at 183 °C with pure O2 and H2 as the oxidant and fuel, respectively. The synthesized membrane also shows excellent acid retention under mechanical load and high humidity, a valued characteristic for high-temperature PEMs. These performance-ensuring properties paired with a low-cost synthesis approach demonstrate the new membrane to be a viable candidate as a high-temperature PEM.

Graphical abstractA new class of high-temperature proton exchange membrane is synthesized through imbibing H3PO4 into 3D framework of PAM/PVA hydrogel. The measured proton conductivity reaches 0.0525 S cm−1 at 183 °C under anhydrous conditions. The high proton conductivity, along with good H3PO4 retention ability, thermal, chemical and mechanical stabilities, reasonable fuel cell performance, low-cost, simple and scalable synthesis procedure, and competitive cost, promises the new PEM to find applications in high-temperature PEMFCs.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► PAM/PVA semi-IPN hydrogel membranes were employed to fabricate HTPEMFCs. ► The anhydrous proton conductivity reached 0.0525 S cm−1 at 183 °C. ► The unique absorption and retention of hydrogel membranes make them candidates in HTPEMs.