Ultra‐Stable, Highly Proton Conductive, and Self‐Healing Proton Exchange Membranes Based On Molecule Intercalation Technique and Noncovalent Assembly Nanostructure

Proton exchange membranes (PEMs) that can heal mechanical damage to restore original functions are imperative for fabricating reliable and durable proton exchange membrane fuel cells (PEMFCs). Here, an ultra‐stable, highly proton conductive self‐healing PEM via hydrogen‐bonding complexation between Nafion and poly(vinyl alcohol) (PVA) followed by incorporation of sodium lignosulfonate (SLS) intercalation‐modified graphene oxide (GO) and post‐modification with 4‐formylbenzoic acid (FBA) is presented. Notably, the introduction of GO complexes and post‐modification of FBA molecules effectively improves the stability of composite membranes and also participate in the establishment of proton‐conducting nanochannels. Compared with recast Nafion, the FBA‐Nafion/PVA@SLS/GO composite membranes exhibit enhanced mechanical properties (36.2 MPa at 104.8% strain) and higher proton conductivity (0.219 S cm−1 at 80 °C‐100% RH and 23.861 mS cm−1 at 80 °C‐33% RH, respectively). More importantly, the incorporated PVA gives the FBA‐Nafion/PVA@SLS/GO composite membranes superior self‐healing capabilities that can heal mechanical damage of several tens of micrometers in size and restore their original proton conductivity under the operating conditions of the PEMFCs. This study opens an avenue toward the development of reliable and durable PEM for PEMFCs. A complex with intrinsic self‐healing ability by blending poly(vinyl alcohol) (with abundant hydroxyl groups) with Nafion is successfully developed. Subsequently, graphene oxide modified by sodium lignosulfonate intercalation and the post‐modification of 4‐formylbenzoic acid molecules, is introduced. The resulting composite membrane exhibits low sensitivity to moisture and defects, superior stability, and surprisingly high proton conductivity.