Intermolecular Acid–Base‐Pairs Containing Poly (p‐Terphenyl‐co‐Isatin Piperidinium) for High Temperature Proton Exchange Membrane Fuel Cells

Abstract

How to optimize and regulate the distribution of phosphoric acid in matrix, and pursuing the improved electrochemical performance and service lifetime of high temperature proton exchange membrane (HT‐PEMs) fuel cell are significant challenges. Herein, bifunctional poly (p‐terphenyl‐co‐isatin piperidinium) copolymer with tethered phosphonic acid (t‐PA) and intrinsic tertiary amine base groups are firstly prepared and investigated as HT‐PEMs. The distinctive architecture of the copolymer provides a well‐designed platform for rapid proton transport. Protons not only transports through the hydrogen bond network formed by the adsorbed free phosphoric acid (f‐PA) anchored by the tertiary amine base groups, but also rely upon the proton channel constructed by the ionic cluster formed by the t‐PA aggregation. Thorough the design of the structure, the bifunctional copolymers with lower PA uptake level (<100%) display prominent proton conductivities and peak power densities (99 mS cm−1, 812 mW cm−2 at 160 °C), along with lower PA leaching and higher voltage stability, which is a top leading result in disclosed literature. The results demonstrate that the design of intermolecular acid–base‐pairs can improve the proton conductivity without sacrificing the intrinsic chemical stability or mechanical property of the thin membrane, realizing win‐win demands between the mechanical robustness and electrochemical properties of HT‐PEMs.

Construction of Successive Proton Conduction Channels to Accelerate the Proton Conduction Process in Flexible Proton Exchange Membranes

“…By contrast, the RW values were 59.1% for (K/PA/S) 3 -f/PA and 70.0% for (K/PA/S) 3 -50/PA. Additionally, the reported RW values were 77.6% for PPB/OPBI/PA at 80 °C and 40% relative humidity (RH), (60–64)% for NbPBI-TSPDO at 80 °C and 40% RH, and 90% for P/PTIP-20 at 100 °C . Liu and co-workers believed that a quick weight decrease usually occurred in the initial period for PA-doped composite membranes …”

“…Wang and co-workers reported that the 40%-OPBI membrane exhibited the conductivity loss of 12.2% with the ultimate value of 0.16 S cm –1 after the conductivity stability test for 72 h at 160 °C . Meng and co-workers reported the 70%PA@P/PTIP-40 membrane with the proton conductivity retention of 78% for 140 h at 180 °C owing to the intermolecular interaction between components …”

“…Additionally, the reported RW values were 77.6% for PPB/OPBI/PA at 80 °C and 40% relative humidity (RH), 33 (60−64)% for NbPBI-TSPDO at 80 °C and 40% RH, 34 and 90% for P/PTIP-20 at 100 °C. 35 Liu and coworkers believed that a quick weight decrease usually occurred in the initial period for PA-doped composite membranes. 36 For the folded and stretched membranes, the decline in stiffness with withdrawing external force was a concerned issue.…”

“…57 Meng and co-workers reported the 70%PA@P/PTIP-40 membrane with the proton conductivity retention of 78% for 140 h at 180 °C owing to the intermolecular interaction between components. 35 3.10. Single Proton Exchange Membrane Fuel Cell Performance.…”

The effect of grafted alkyl side chains on the properties of poly(terphenyl piperidinium) based high temperature proton exchange membranes

“…Thus, the design and fabrication of new HT-PEMs with good thermal stability, modest mechanical properties and excellent proton conductivity have been encouraged. 5,8,15 Alternatively, a variety of potential candidate polymer materials with side-chain or main-chain basic groups have been designed and realized. For example, aromatic polymer materials containing pyridine 16 and quinolone 17 have been synthesized, and pyrrolidone 18,19 and imine 20,21 containing polyolefins have been selected as HT-PEMs as well.…”