Self-assembled lamellar nanochannels in polyoxometalate-polymer nanocomposites for proton conduction

The construction of nanostructured ion-transport channels is highly desirable in the design of advanced electrolyte materials,as it can enhance ion conductivity by offering short ion-transport pathways.In this work,we present a supramolecular strategy to fabricate a nanocomposite electrolyte containing highly ordered lamellar proton-conducting nanochannels,by the electrostatic self-assembly of a polyoxometalate H_(3)PW1_(2)O_(4)O(PW)and a comb copolymer poly(4-methlstyrene)-graft-poly(N-vinyl pyrrolidone).PW can effectively regulate the self-assembling order of polymer moieties to form a large-ra nge lamellar structure,meanwhile,introducing protons into the nanoscale lamellar domains to build proton transport channels.Moreover,the rigid PW clusters contribute a remarkable mechanical reinforcement to the nanocomposites.The lamellar nanocomposite exhibits a conductivity of 4.3×10^(-4)S/cm and a storage modulus of 1.1×10^(7)Pa at room temperature.This study provides a new strategy to construct nanostructured ion-conductive pathways in electrolyte materials.

Nanostructured Polymer Composite Electrolytes with Self-Assembled Polyoxometalate Networks for Proton Conduction

The key challenge for the use of polymer electrolytes is to realize a high ionic conductivity without scarifying their mechanical performance.Herein,we report a facile strategy to prepare a nanostructured polymer electrolyte with both high proton conductivity and high modulus,based on the electrostatic self-assembly of polyoxometalate cluster H_(3)PW_(12)O_(40)(PW)and comb copolymer poly(ether-etherketone)-grafted-poly(vinyl pyrrolidone)(PEEK-gPVP).The incorporation of protonic acid PW can enable the PEEK-g-PVP to be highly proton conductive and create flexible composite electrolyte membranes.Moreover,nanoscale phase separation between PEEK domains and PVP/PW domains spontaneously occurs in these membranes,forming a bicontinuous structure with three-dimensional(3D)-connected PW networks.Due to the dual role of PW networks as both proton transport pathways and mechanical enhancers,these membranes exhibit proton conductivities higher than 30 mS cm^(−1) and modulus over 4 GPa.Notably,the direct methanol fuel cells equipped with these membranes show good cell performance.Given the wide tunability of comb copolymers and polyoxometalates,this system can be extended to develop a variety of functional electrolyte materials,for example,the lithium-ion conductive electrolytes by using polyoxometalatebased lithium salts,which provides a promising platform to explore versatile electrolyte materials for energy and electronic applications.