Sulfonation modification of halloysite nanotubes for the in-situ synthesis of polybenzimidazole-based composite proton exchange membranes in wide-temperature range applications

•The sHNT improved the interfacial compatibility between the inorganic particles and the polymer matrix due to the acid–base interactions.•High proton conductivity was due to the fast proton conduction paths of the sHNT and the well-constructed interface.•The peak power density of the PA-doped 3 % sHNT/ABPBI composite membrane reached 0.212 W cm−2 at 160 °C under anhydrous conditions.