The dilemma of employing high-capacity battery materials and maintaining the electrodes’ electrical and mechanical integrity requires a unique binder system design. Polyoxadiazole (POD) is an n-type conductive polymer with excellent electronic and ionic conductive properties, which has acted as a silicon binder to achieve high specific capacity and rate performance. However, due to its linear structure, it cannot effectively alleviate the enormous volume change of silicon during the process of lithiation/delithiation, resulting in poor cycle stability. This paper systematically studied metal ion (i.e., Li+, Na+, Mg2+, Ca2+, and Sr2+)-crosslinked PODs as silicon anode binders. The results show that the ionic radius and valence state remarkably influence the polymer’s mechanical properties and the electrolyte’s infiltration. Electrochemical methods have thoroughly explored the effects of different ion crosslinks on the ionic and electronic conductivity of POD in the intrinsic and n-doped states. Attributed to the excellent mechanical strength and good elasticity, Ca-POD can better maintain the overall integrity of the electrode structure and conductive network, significantly improving the cycling stability of the silicon anode. The cell with such binders still retains a capacity of 1770.1 mA h g–1 after 100 cycles at 0.2 C, which is ∼285% that of the cell with the PAALi binder (620.6 mA h g–1). This novel strategy using metal-ion crosslinking polymer binders and the unique experimental design provides a new pathway of high-performance binders for next-generation rechargeable batteries.

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Dihydroxyl poly(1,3,4‐oxadiazole) (DHPOD) polymers are synthesized by copolymerization of 2,5‐dihydroxyterephthalic acid (2,5‐DHTA) and terephthalic acid with hydrazine sulfate in oleum, and then DHPOD fibers are prepared by wet‐spinning. The effects of UV irradiation on POD fibers' mechanical properties and surface morphology with and without hydroxyl groups were investigated. As proved by tensile testing and scanning electron microscope measurement, the UV resistance of DHPOD fibers is improved compared to that of p‐POD fibers. Besides, the heat resistance of POD fibers is not damaged by the introduction of phenolic hydroxyl groups. The UV and fluorescence spectra are used to analyze the UV resistance mechanism of the POD containing phenolic hydroxyl groups. Results show that the UV resistance mechanism of DHPOD is related to the proton transfer reaction between the 1,3,4‐oxadiazole ring and ortho phenolic hydroxyl group.

Flame retardant poly(ethylene terephthalate) (FRPET) fabrics are widely used in daily life. However, the meltdrop and visible smoke produced during combustion significantly limit its further application. This study proposes a simple but effective method of fiber-blending to improve the above shortcomings. On the basis of synergistic flame retardancy of nitrogen and phosphorus, the FRPET was blended with flame retardant viscose (FRV) and intrinsic nitrogen-containing flame retardant fibers (NIFRFs), to prepare the binary and ternary blended FRPET samples labeled as NIFRF/FRPET and FRV/NIFRF/ FRPET, respectively. The limiting oxygen index and cone calorimeter test show that the ternary-blending could effectively suppress the combustion of FRPET fiber composite. The smoke density test and UL-94 vertical combustion test indicate that ternary-blending could better improve the meltdrop characteristics and smoke suppression property than binary-blending. Among all samples, FRV/PMIA/FRPET (1:4:5) owns the highest LOI of 32.6% and lowest smoke density of 61.37. The investigation of residual char utilizing scanning electron microscopy, the X-ray photoelectron spectroscopy and the Laser Raman spectroscopy demonstrates that the FRPET meltdrop would adhere to the surface of component fibers to avoid droplets. Besides, fiber-blending could increase the yield and degree of graphitization of residual char, which is conducive to improving samples' flame retardancy through the condensed phase. This work may provide a workable strategy to expand the application areas of FRPET fabrics.