High ionic conductivity, good mechanical strength, strong electrode adhesion, and low volatilization are highly desired properties for flexible solid electrolytes. However, it is difficult to realize all these properties simultaneously, which needs a rational synergy of different electrolyte constituents. Here, we present the use of polyoxometalates as versatile enhancers to fabricate nonvolatile flexible hybrid polymer electrolytes with improved conductive, stretchable, and adhesive properties. These electrolytes are based on the molecular hybridization of a polyacrylate elastomer, phosphoric acid, and a commercial polyoxometalate H3PW12O40 (PW). PW can serve as a nanosized plasticizer to favor the chain relaxation of polyacrylate and improve stretchability. Meanwhile, PW as a solid acid can increase the proton concentration and form a hybrid hydrogen-bonding network to facilitate proton conduction. Besides, the strong adsorption ability of PW on solid surfaces enables the electrolytes with enhanced adhesion. The hybrid electrolyte with 30 wt % PW shows a break stress of 0.28 MPa, a break elongation of 990%, and a conductivity of 0.01 S cm–1 at 298 K, which are 1.8, 1.8, and 2.5 times higher compared to the case without PW, respectively. Moreover, PW enhances the adhesive strength of hybrid electrolytes on polypropylene, steel, and glass substrates. The flexible supercapacitors based on the hybrid electrolytes and polyaniline electrodes hold a stable electrode–electrolyte interface and exhibit a high specific capacitance of 592 mF cm–2 and an excellent capacitance retention of 84% after 6000 charge–discharge cycles. These results demonstrate great potential of polyoxometalates as multifunctional enhancers to design hybrid electrolyte materials for energy and electronic applications.

Supramolecular polymers (SPs) exhibit intriguing benefits in functional soft materials due to their dynamic bonding feature. However, most SPs can only exist in the solution state and fail to form bulk materials, which limits their applications. Here, we report the fabrication of semi-solid bulk SP materials by using polyoxometalate (POM) nanoclusters as supramolecular cross-linkers to solidify a deep eutectic solvent (DES). The abundant protons and strong hydrogen bonds afforded by POMs enable these SP materials as superprotonic conductive electrolytes with sufficient mechanical strength, showing a proton conductivity more than 1 × 10 À 4 S cm À 1 and a breaking strength exceeding 1 MPa at room temperature. Moreover, the thermodynamic reversibility of the SP electrolytes allows them to form a stable electrode-electrolyte interface by a facile meltinfiltration strategy upon mild heating, which leads to improved performance in supercapacitors. This work presents an innovative DES/POM hybrid system as a promising platform to develop functional supramolecular materials for energy and electronic applications.

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High-temperature proton exchange membranes (HT-PEMs) are key components in high-temperature energy storage and conversion technologies, which require excellent proton conductivity and mechanical strength. However, it is difficult for HT-PEMs to balance their mechanical and conductive properties. Here, we present a strategy to prepare HT-PEMs based on the combination of polyoxometalate (POM)-dominated noncovalent cross-linking and H 3 PO 4 (PA)-induced post-assembly. Hybrid membranes containing polyvinylpyrrolidone (PVP), poly(terphenyl piperidine) (PTP), and H 3 PW 12 O 40 (PW) are prepared, where the polymers are electrostatically cross-linked by PW and maintain certain mobility. When the membranes adsorb PA, the polarity difference between the PVP−PW−PA moieties and the PTP−PW−PA moieties increases, causing the chains to rearrange into bicontinuous structures via a post-assembly process. The resultant membranes show a break strength over 7 MPa and a proton conductivity of ∼55 mS cm −1 at 160 °C. The high-temperature supercapacitors based on such membranes exhibit a specific capacitance of 145.4 F g −1 and a capacitance retention of 80% after 3000 charge−discharge cycles at 150 °C. Their H 2 /air fuel cells display a peak power of 273.6 mW cm −2 at 160 °C. This work provides a paradigm for using POMs as dynamic cross-linkers to fabricate nanostructured PEMs, which paves a feasible route to developing high-performance electrolyte materials.

Nafion, as the mostly used proton exchange membrane material in vanadium redox flow batteries (VRFBs), encounters serious vanadium permeation problems due to the large size difference between its anionic nanophase (3–5 nm) and cationic vanadium ions (∼0.6 nm). Bulk hybridization usually suppresses the vanadium permeation at the expense of proton conductivity since conventional additives tend to randomly agglomerate and damage the nanophase continuity from unsuitable sizes and intrinsic incompatibility. Here, we report the ionic-nanophase hybridization strategy of Nafion membranes by using fluorinated block copolymers (FBCs) and polyoxometalates (POMs) as supramolecular patching additives. The cooperative noncovalent interactions among Nafion, interfacial-active FBCs, and POMs can construct a 1 nm-shrunk ionic nanophase with abundant proton transport sites, preserved continuity, and efficient vanadium screeners, which leads to a comprehensive enhancement in proton conductivity, selectivity, and VRFB performance. These results demonstrate the intriguing potential of the supramolecular patching strategy in precisely tuning nanostructured electrolyte membranes for improved performance.