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With the escalating issue of air pollution, the development of air filtration materials that can efficiently remove particulate pollutants, particularly nanosized particles, from air has attracted more and more research attention in recent years. Electrospun nanofiber membranes with a nanoscale pore structure have been widely used as air filtration materials. Along these lines, in this work, polyvinylidene fluoride-co-hexafluoropropyle (PVDF-HFP) nanofiber membranes with a multihierarchical gradient structure were fabricated by varying the sodium dodecyl sulfate (SDS) concentration. The proposed multihierarchical gradient structure was composed of upper, middle, and lower nanofiber layers, which could effectively filter PM0.3. The decreased nanofiber diameter by increasing the SDS concentration was attributed to the low surface tension and high charge balance. Compared with the single- and double-hierarchical PVDF-HFP nanofiber membranes, the triple-hierarchical PVDF-HFP nanofiber membranes demonstrated excellent air filtration performance. Among them, F014 yielded optimal air filtration performance, exhibiting a high filtration efficiency of 99.50%, a low pressure drop of 71.4 Pa, and a quality factor of 0.0878 Pa–1. Furthermore, the filtration efficiency was maintained above 99% and the pressure drop just increased by 27.4% over a 40 min air filtration test, which indicated that F014 showcased exceptional durability, owing to the multihierarchical gradient structure. Our work paves the way for the fabrication of electrospun nanofiber membranes with a multihierarchical gradient structure using a straightforward method, highlighting their potential as an alternative to traditional air filter materials for various practical applications. [ABSTRACT FROM AUTHOR]

Wrinkling phenomena has attracted wide attention owing to its applications in anticounterfeiting patterns, smart windows, flexible devices, and sensors, and the dynamic morphological transformations of wrinkle structure extend the application in dynamic displays, patterning, and surface wetting. However, developing simple and effective wrinkle morphology transformation strategies to design smart windows with good repeatability and stable properties presents ongoing challenges. In this paper, morphology transition of the wrinkle structure is presented to develop potential applications in smart window and pattern fabrication. At first, a nanoscale wrinkled structure was fabricated by immersing an ionic liquid mixed solution with poly-(vinylidene fluoride)-hexafluoropropylene over a colloidal assembly based on the mismatch modulus between the surface layer and the interior during solvent evaporation. The wrinkle structure can be erased to form a pattern by inkjet printing based on the ink-induced dispersion of the ionic liquid. Interestingly, the wrinkled and erased structures have completely opposite optical reversible responsiveness to humidity changes, which forms the basis of a smart window. This wrinkled structure shows promising applications in anticounterfeit patterning, smart windows, and antiglare materials, which provides guidelines for the development of wrinkled-based optic materials and devices. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) have revolutionized the energy storage landscape and are the preferred power source for various applications, ranging from portable electronics to electric vehicles. The constant drive and growth in battery research and development aim to enhance their performance, energy density, and safety. Advanced lithium batteries (LIBs) are considered to be the most promising electrochemical storage devices, which can provide high specific energy, volumetric energy density, and power density. However, the trade-off between ionic conductivity and cycling stability is still a major contradiction for SPEs. In this work, a novel hydroxylated PAF-1 was designed and synthesized through post-modification, and the lithium-rich single-ion porous aromatic framework PAF-1-OLi was thereafter prepared by lithiation, achieved with a specific surface area to be 155 m 2 g -1 and a lithium content of 2.01 mmol g -1 . PAF-1-OLi, lithium bis(trifluoromethanesulfony)limine (LiTFSI), and poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) were compounded to obtain PAF-1-OLi/PVDF by solution casting, which had good mechanical, thermodynamic, and electrochemical properties. The ion conductivity of PAF-1-OLi/PVDF infiltrated with plasticizer was 2.93 × 10 -4 S cm -1 at 25 °C. The t Li + was 0.77, which was much higher than that of the traditional dual-ion polymer electrolytes. The electrochemical window of PAF-1-OLi/PVDF can reach 4.9 V. The Li//PAF-1-OLi/PVDF//LiFePO 4 battery initial discharge specific capacity was 147 mAh g -1 and reached 134.9 mAh g -1 after 600 cycles with a capacity retention rate of 91.2%, demonstrating its good cycling stability. The anionic part of lithium salt was fixed on the framework of PAF-1 to increase the Li + transfer number of PAF-1-OLi/PVDF. The lithium-rich PAF-1-OLi and the LiTFSI provided abundant Li + sources to transfer, while PAF-1-OLi helped to form a continuous Li + transport channel, effectively promoting the migration of Li + in the PAF-1-OLi/PVDF and effectively improving the Li + conductivity. This study afforded a novel polymer electrolyte based on lithium-rich PAF-1-OLi, which has excellent electrochemical performance, providing a new choice for the polymer electrolyte of lithium batteries.

Solid polymer electrolytes (SPEs) are regarded as a superior alternative to traditional liquid electrolytes of lithium-ion batteries (LIBs) due to their improved safety features. The practical implementation of SPEs faces challenges, such as low ionic conductivity at room temperature (RT) and inadequate interfacial contact, leading to high interfacial resistance across the electrode and electrolyte interfaces. In this study, we addressed these issues by designing a quasi-gel polymer electrolyte (QGPE), a blend of poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP), poly(ethylene oxide) (PEO), and succinonitrile (SN), with the desired mechanical strength, ionic conductivity, and interfacial stability through a simple solution casting technique. The QGPE features a thin solvated PEO layer on its surface, which wets the electrode, reducing the interfacial resistance and ensuring a homogeneous Li-ion flux across the interface. The optimized QGPE exhibits a good lithium-ion conductivity of 1.14 × 10 -3 S cm -1 with a superior lithium-ion transference number of 0.7 at 25 °C. The Li/QGPE/Li symmetric cell exhibits a highly reversible lithium plating/stripping process for over 1300 h with minimal voltage polarization of ∼20 mV. The Li/QGPE/LiFePO 4 full cell demonstrates good rate capability and excellent long-term cycling performance at a 0.1 C rate at 25 °C, maintaining a specific discharge capacity of 148 mAh g -1 over 200 cycles. The effectiveness of QGPE for LIBs is proven using a graphite/QGPE/LiFePO 4 4 × 4 cm pouch cell, showcasing outstanding flexibility and tolerance against intentional abuse.

To further advance the application of flexible piezoelectric materials in wearable/implantable devices and robot electronic skin, it is necessary to endow them with a new function of antibacterial properties and with higher piezoelectric performance. Introducing a specially designated nanomaterial based on the nanocomposite effect is a feasible strategy to improve material properties and achieve multifunctionalization of composites. In this paper, carbon dots (CDs) were sensitized onto the surface of ZnO to form ZnO@CDs nanoparticles, which were then incorporated into polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) to obtain a multifunctional composite. On the one hand, the antibacterial property of ZnO was improved because CDs had good optical absorption of visible light and their surface functional groups were favorable for electrostatic adsorption with bacteria. Therefore, ZnO@CDs endowed the composite with an outstanding antibacterial rate of 69.1% for Staphylococcus aureus . On the other hand, CDs played a bridging role between ZnO and PVDF-HFP, reducing the negative effect of ZnO aggregation and interface incompatibility with PVDF-HFP. As a result, ZnO@CDs induced β-phase formation of 80.4% in PVDF-HFP with a d 33 value of 33.8 pC N -1 . The multifunctional device exhibited excellent piezoelectric and antibacterial performance in the application of energy harvesters and self-powered pressure sensors.

Aqueous rechargeable zinc-based batteries have recently gained tremendous attention because of their low cost and high safety. However, the issues associated with the zinc metal anode, including corrosion, H 2 evolution, and dendrite growth, hinder their practical applications. Herein, we design a hybrid organic/inorganic interphase composed of poly(vinylidene fluoride-co-hexafluoropropylene), silica, and zinc triflate to stabilize the zinc metal anode in a mild aqueous electrolyte. It is proven that the artificial interphase reduces corrosion of the Zn metal in the ZnSO 4 electrolyte and suppresses dendrite growth by regulating Zn 2+ deposition. Therefore, the lifespan of symmetrical cells with coated Zn could be enhanced to over 960 h with a stripping/plating capacity of 0.5 mAh cm -2 . In addition, zinc-ion batteries including a sodium vanadate cathode and a coated Zn anode could achieve 3000 cycles with nearly no capacity fading at 5 A g -1 .

The demand for more efficient energy storage devices has led to the exponential growth of lithium-ion batteries. To overcome the limitations of these systems in terms of safety and to reduce environmental impact, solid-state technology emerges as a suitable approach. This work reports on a three-component solid polymer electrolyte system based on poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP), the ionic liquid 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]), and clinoptilolite zeolite (CPT). The influences of the preparation method and of the dopants on the electrolyte stability, ionic conductivity, and battery performance were studied. The developed electrolytes show an improved room temperature ionic conductivity (1.9 × 10 -4 S cm -1 ), thermal stability (up to 300 °C), and mechanical stability. The corresponding batteries exhibit an outstanding room temperature performance of 160.3 mAh g -1 at a C/15-rate, with a capacity retention of 76% after 50 cycles. These results represent a step forward in a promising technology aiming the widespread implementation of solid-state batteries.

Sulfide-based lithium (Li)-ion conductors represent one of the most popular solid electrolytes (SEs) for solid-state Li metal batteries (SSLMBs) with high safety. However, the commercial application of sulfide SEs is significantly limited by their chemical instability in air and electrochemical instability with electrode materials (metallic Li anode and oxide cathodes). To address these difficulties, here, we design and successfully demonstrate a novel sulfide-incorporated composite electrolyte (SCE) through the combination of inorganic sulfide Li argyrodite (Li 7 PS 6 ) with poly(vinylidenefluoride- co -hexafluoropropylene) (PVDF-HFP) polymer. In this composite structure, Li 7 PS 6 is embedded in PVDF-HFP polymer matrix, making the SCE flexible and air-stable and achieve great chemical and electrochemical stability. Meanwhile, the presence of sulfide facilitates Li-ion transport in SCE, leading to a superior room-temperature ionic conductivity of 1.1 × 10 -4 S cm -1 . Using the SCE with enhanced stability while maintaining high conductivity, Li||Li symmetric cells achieved stable cycling up to 1000 h at 0.2 mA cm -2 . In addition, LiFePO 4 (LFP)||SCE||Li cells can deliver an impressive specific capacity of 160 mAh g -1 over 150 cycles. These features indicate that Li 7 PS 6 /PVDF-HFP SCE is a promising candidate to contribute to the practical development of SSLMBs.

A stretchable transparent double network ionogel composed of physically cross-linked poly(vinylidene fluoride- co -hexafluoropropylene) (P(VDF- co -HFP)) and chemically cross-linked poly(methyl methacrylate- co -butylmethacrylate) (P(MMA- co -BMA)) elastomer networks within [EMIM][TFSI] ionic liquid was fabricated through a facile one-pot thermal polymerization. The dual-network (DN) ionogel presents good mechanical performance (failure tensile stress 2.31 MPa, strain 307%) with a high loading of ionic liquid (70 wt %) for achieving required ionic conductivity (>0.1 S/m at room temperature). The transparent chemical cross-linked P(MMA- co -BMA) elastomer network endows high transparency (>93%) and high stretchability to the DN ionogel. The DN ionogel maintains good toughness, elasticity, and transparency in a wide temperature range (-40 to 80 °C) for the application in a harsh environment. In addition, the sensitivity of the DN ionogel to the change of environment temperature and deformation was detected and described. The practical potential of the DN ionogel in flexible electronic devices is further revealed by fabricating DN ionogel strain sensors to detect the movement of different human limbs including the bending of the finger, wrist, and elbow as well as the slight throat jitter during the swallowing and vocalization, showing fast response, high sensitivity, and good repeatability.

The rational design and exploration of safe, robust, and inexpensive energy storage systems with high flexibility are greatly desired for integrated wearable electronic devices. Herein, a flexible all-solid-state battery possessing competitive electrochemical performance and mechanical stability has been realized by easy manufacture processes using carbon nanotube enhanced phosphate electrodes of LiTi 2 (PO 4 ) 3 and Li 3 V 2 (PO 4 ) 3 and a highly conductive solid polymer electrolyte made of polyphosphazene/PVDF-HFP/LiBOB [PVDF-HFP, poly(vinylidene fluoride- co -hexafluoropropylene)]. The components were chosen based on their low toxicity, systematic manufacturability, and (electro-)chemical matching in order to ensure ambient atmosphere battery assembly and to reach high flexibility, good safety, effective interfacial contacts, and high chemical and mechanical stability for the battery while in operation. The high energy density of the electrodes was enabled by a novel design of the self-standing anode and cathode in a way that a large amount of active particles are embedded in the carbon nanotube (CNT) bunches and on the surface of CNT fabric, without binder additive, additional carbon, or a large metallic current collector. The electrodes showed outstanding performance individually in half-cells with liquid and polymer electrolyte, respectively. The prepared flexible all-solid-state battery exhibited good rate capability, and more than half of its theoretical capacity can be delivered even at 1C at 30 °C. Moreover, the capacity retentions are higher than 75% after 200 cycles at different current rates, and the battery showed smaller capacity fading after cycling at 50 °C. Furthermore, the promising practical possibilities of the battery concept and fabrication method were demonstrated by a prototype laminated flexible cell.

This paper presents a simultaneous microscopic structure characteristic of shape-memory (SM) poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) inverse opals together with a bulk PVDF-HFP by scanning electron microscopy (SEM). The materials show a thermo-sensitive micro-SM property, accompanied with a reversible and modulated optical property. The introduction of the inverse opal structure into the shape-memory polymer material renders a recognition ability of the microstructure change aroused from complex environmental signals by an optical signal, which can be simultaneously detected by SEM. Furthermore, this feature was applied as a reversible write/erase of fingerprint pattern through the press-stimulus and solvent-induced effect, together with the changes of morphology/optical signal. This micro-SM property can be attributed to the shrink/swell effect of the polymer chain from external stimuli combined with the microscopic structure of inverse opals. It will trigger a promising way toward designing reversible micro-deformed actuators.