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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.

Gel polymer electrolytes have the advantages of both a solid electrolyte and a liquid electrolyte. As a transitional product before which a solid electrolyte can be comprehensively used, gel polymer electrolytes are of great research value. They can reduce the risk of spontaneous combustion and explosion caused by leakage during the use of conventional liquid electrolytes. Poly(vinylidene-fluoride-co-hexafluoropropylene) (PVDF–HFP), a material with excellent performance, has been widely utilized in the preparation of gel polymer electrolytes. Here, PVDF–HFP-based gel polymer membranes with polyvinyl pyrrolidone (PVP) pores were prepared using a phase inversion method, and Octavinyl-polyhedral oligomeric silsesquioxane (OVAPOSS) was doped to improve its temperature resistance as well as its ionic conductivity, to enhance its safety and electrochemical performance. The final prepared polymer membrane had a porosity of 85.06% and still had a certain mechanical strength at 160 °C without any shrinkage. The gel polymer electrolyte prepared with this polymer membrane had an ionic conductivity of 1.62 × 10−3 S·cm−1 at 30 °C, as well as an electrochemical window of about 5.5 V. The LiCoO2-Li button half-cell prepared therefrom had a specific capacity of 141 mAh·g−1 at a rate of 1C. The coulombic efficiency remained above 99% within 100 cycles and the capacity retention rate reached 99.5%, which reveals an excellent cycling stability. [ABSTRACT FROM AUTHOR]

Nowadays, the development of sustainable and wearable energy harvesters is gaining an increasing interest. Herein, an approach used to develop a high performance flexible nanogenerator based on hybrid piezoelectric composite is reported. The approach consists first of employing solution mixing method with different solvents to determine the suitable solvent for achieving higher piezoelectric property of the piezoceramic polymer composites. Then, integration of conductive silver nanoparticles is done to boost the performance of the nanogenerator (NG). Different aspects are considered which are the homogeneity of particles distribution within PVDF-HFP and the crystallinity of the composite using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). This study demonstrates the efficiency of dimethyl formamide (DMF) solvent to increase the rate of crystalline phases due to their moderate evaporation rate and their high dipole moment that leads to enhanced piezoelectric performance. This approach proves its effectiveness to strengthen the piezoelectric performance especially by doping with silver nanoparticles (Ag NPs). The composite exhibits improved output voltage around 2.21 V and an output power of 0.22 μW, which are, respectively, around three times and 9 times higher than the composite without Ag NPs. In addition, the NG shows good stability over 900 cycles illustrating their robustness. The followed approach extends the performance limits of PVDF-HFP based NGs and their potential applications. Also, we have proved the potential of the optimized NG to harvest mechanical energy from human activities, with ability to generate around 3.56 V by striking with a palm hand. Figure. Graphical abstract shows the structure of the nanogenerator and its working mechanisms and its potential applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Pouch-type hybrid Li-air batteries with an air-breathing ability and lightweight packaging provide improved specific energy compared with commercial Li-ion batteries and Li–O 2 batteries that require oxygen supply equipment. Because ceramic Li-ion conductors, used to separate aprotic and aqueous electrolytes, are brittle and inflexible, hybrid Li-air batteries are difficult to assemble into pouch cells for use in flexible device applications. A flexible pouch-type hybrid Li-air battery is realized by utilizing a flexible composite lithium-ion conducting membrane (FCLICM). This FCLICM, consisting of sol-gel-derived Li 1+x Al x Ti 2-x (PO 4) 3 (LATP) as a Li-ion conductor and a chemically compatible poly (vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) polymer matrix, is produced by the tape-casting technique and applied in hybrid Li-air batteries. An assembled pouch-type hybrid Li-air battery containing a lithium foil anode, an aprotic electrolyte, an FCLICM, an aqueous electrolyte and a platinum air cathode is operated in ambient air, exhibiting a high capacity of 200 mAh g−1 with a cycle life of 12 cycles (48 h). This pouch cell shows an open-circuit voltage of 3.16 V regardless of being flat or bent, demonstrating its flexibility and electrochemical stability and its potential for use in wearable technology. Image 1 • First reported flexible pouch-type hybrid electrolyte Li-air battery. • PVDF-HFP and LATP nanoparticles enable FCLICM to be flexible and Li-ion conductive. • FCLICM as water permeation barrier between aprotic and aqueous electrolytes. • Hybrid Li-air batteries show air-breathing and cycling abilities in ambient air. [ABSTRACT FROM AUTHOR]

• Different lithium salts at various concentrations were impregnated into PVDF:HFP polymer matrix to reveal their effects in various electrochemical performances of Li-O 2 batteries. • Opaque and transparent gel-polymer electrolytes(GPE) were obtained by changing the substrate temperature in which the GPE poured onto. • GPE was coated onto the Gas Diffusion Layer (GDL) cathode to increase the intimate contact. • FTIR analysis was carried out to ascertain the impregnation of lithium salts into PVDF:HFP matrix. • Our results indicate the need for the development of a lithium salts capable of serving decent electrochemical performance in all aspects of electrochemistry. Among rechargeable lithium batteries, lithium-oxygen batteries (Li-O 2) offer remarkable energy densities which make them to be considered as the next generation energy storage systems. However, intrinsic problems arising from the use of liquid electrolytes has to be overcome before their adoption into the market. Gel-polymer electrolytes (GPEs) are now considered as the next-generation electrolytes to be utilized in Li-O 2 systems. PVDF-HFP polymers with different lithium salts were successfully utilized as gel-polymer electrolytes to replace liquid electrolytes in Li-O 2 batteries. However, the electrochemical performance of different lithium salts dissolved in PVDF-HFP matrices are limited in different aspects, i.e. (electro)chemical stability, ionic conductivity, interfacial stability, cycle stability or lithium-ion transference number. In this study, we systematically observed the effect of different lithium salts at various concentrations on the above mentioned electrochemical properties. Our results indicate that LiPF 6 salt imparts best ionic conductivity into GPE systems while LiTFSI has both the widest electrochemical window and highest lithium-ion transference number. Our results indicate that the synthesis of new lithium salts having decent electrochemical performance in all aspects is of great importance in developing GPE systems. [ABSTRACT FROM AUTHOR]

• First preparation of 3Li 2 S-2MoS 2 as active filler. • The 3Li 2 S-2MoS 2 improves the ionic conductivity and mechanical properties. • The composite polymer electrolyte demonstrates excellent interface performance. Solid polymer electrolytes (SPEs) are close to commercialization owing to their high flexibility, low cost, and easy processing. However, the further commercial applications of SPE are hindered by low ionic conductivity and poor mechanical properties. To solve the problems, a porous and intercalated 3Li 2 S-2MoS 2 (LMS) was prepared as an active filler. LMS and lithium oxalyldifluroborate (LiODFB) were embedded with the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) in a composite intercalated solid polymer electrolyte (CSE-LMS). The CSE-LMS exhibits excellent properties such as high ionic conductivity (2.51 × 10-4 S·cm−1 at 60 ℃) with a favorable stability electrochemical window of 4.8 V (vs. Li/Li+), superior interface stability with lithium metal and outstanding mechanical strength. The LiCoO 2 /CSE-LMS/Li cell was assembled to construct a high specific energy device, which delivered excellent C-rate performance and a specific capacity of 145.79 mA·h·g−1 with a capacity retention of > 86.22% after 200 cycles at 0.5C. The LMS reduces polymer crystallinity and stablizes the interface conformation achieved by LMS interacting with PVDF-HFP and LiODFB. The results suggest that CSE-LMS12 doped with 12 wt% LMS is a promising SPE for solid-state batteries. [ABSTRACT FROM AUTHOR]

Textile-based pressure sensors have garnered considerable interest in electronic textiles due to their diverse applications, including human–machine interface and healthcare monitoring systems. We studied a textile-based capacitive pressure sensor array using a poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP)/ionic liquid (IL) composite film. By constructing a capacitor structure with Ag-plated conductive fiber electrodes that are embedded in fabrics, a capacitive pressure sensor showing high sensitivity, good operation stability, and a wide sensing range could be created. By optimizing the PVDF-HFP:IL ratio (6.5:3.5), the fabricated textile pressure sensors showed sensitivity of 9.51 kPa−1 and 0.69 kPa−1 in the pressure ranges of 0–20 kPa and 20–100 kPa, respectively. The pressure-dependent capacitance variation in our device was explained based on the change in the contact-area formed between the multi-filament fiber electrodes and the PVDF-HFP/IL film. To demonstrate the applicability and scalability of the sensor device, a 3 × 3 pressure sensor array was fabricated. Due to its matrix-type array structure and capacitive sensing mechanism, multi-point detection was possible, and the different positions and the weights of the objects could be identified. [ABSTRACT FROM AUTHOR]

• The polarization of Li+ in HAL with adsorbed H 2 O improved the dielectric constant of composites film effectively. • The adsorbed H 2 O enhanced the β-phase and d 33 by the hydrogen bonds. • The enhanced current of HAL/PVDF-HFP was due to the combined effect of triboelectricity and piezoelectricity. High dielectric material has attracted interest in applications of triboelectric nanogenerators for its high charge-trapping capability. We reported the enhancement of both dielectric and piezoelectric properties by adding modified halloysite (HAL) into PVDF-HFP. Due to the combined effect of triboelectric generation by enhanced dielectric constant and piezoelectric generation by increase of β-phase, the HAL/PVDF-HFP composites film modified by Li+ and water exhibited superior generated current of 9.23 × 10−7 A compared to the pure PVDF-HFP with 1.65 × 10−7 A and unmodified HAL/PVDF-HFP with 2.68 × 10−7 A. This work is expected to inspire the design and fabrication of high dielectric and piezoelectric material for nanogenerators. [ABSTRACT FROM AUTHOR]

Lithium-air batteries (LABs) continue to receive attention as a promising power source because they possess a high theoretical energy density of 3436 Wh L−1. However, the remaining Li2O2 resulting from the irreversible decomposition of Li2O2 during the charge process is one of the key challenges so as to address the deterioration of the cycling performance of LABs. In this study, we propose and report a redox-mediated polymer catalyst (RPC) as a cathode catalyst being composed of LiI and poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) with multi-wall carbon nanotubes (MWCNTs) as the cathode material. In the RPC, iodine molecules are chemically combined with the PVDF-HFP chain. The as-prepared RPC exhibits increased cycling performance by 194% and decreased overpotential by 21.1% at 0.1 mA cm−2 compared to the sample without LiI molecules. Furthermore, these results suggest that the RPC consisting of a polymer chain and redox mediators will be extensively utilized as highly efficient catalysts of LABs. [ABSTRACT FROM AUTHOR]

In this work, porous Cellulose/Poly (vinylidene fluoride hexafluoropropylene) membrane with the incorporation of different amount of titania nanoparticles is prepared by non solvent induced phase inversion (NIPS) method followed by hydrolysis with lithium hydroxide for deacetylation of cellulose acetate. The composite membranes provide interconnected porous structure with high porosity. Titania incorporation and surface modification of Poly (vinylidene fluoride hexafluoropropylene) in the membrane are investigated by Fourier-transform infrared absorbance and transmission tests. The results show that the modified membrane exhibits excellent thermal stability at 200 °C with just only 1% shrinkage and contains high ion conductivity (1.68 mS cm−1). Moreover for window 2.5–4.5V, the ceramic nanoparticles embedded membrane with optimal titania content enables the battery to deliver 97.34% capacity retention after running 100 cycles at 1C rate and to maintain the capacity up to 72% even for 500 cycles after continuing different cycling test with Lithium cobalt oxide/Lithium cell assembly. Image 1 • The cellulose/PVDF-HFP composite membrane with titania nanoparticles is made. • Ecofriendly phase inversion method is applied to create a porous structure. • The membrane is thermally stable at 200 °C without any structure melting. • The membrane exhibits high electrolyte and ion conductivity. • The membrane shows high discharge capacity, long cycling at high charge density. [ABSTRACT FROM AUTHOR]

The gel polymer electrolytes have attracted great attention due to their potential in uniform deposition of lithium, formation of stable SEI, nontoxicity, non-flammability and no leakage. In this work, the PVdF-HFP based gel polymer electrolytes are synthesized by UV-curing method, and the PEGMA and PEGDA are employed to enhance the mechanical properties of the electrolyte by forming 3D semi-interpenetrating polymer network. The PVdF-based gel polymer electrolyte with high ionic conductivity of 4.13 × 10−3 s/cm at room temperature shows superior cycling (140mAh g−1 at 0.5C after 200 cycles) and rate performance (142 mAh g−1 at 0.1C, 123 mAh g−1 at 1C and 90 mAh g−1 at 2C) when LiFePO 4 is used as cathode materials. Moreover, the PVdF-based gel polymer electrolyte displays promising performance under high voltage when the NCM523 is selected as cathode materials (136mAh g−1 at 0.5C after 50 cycles). The excellent electrochemical performance as well as high ionic conductivity of the electrolyte may be ascribed to the remarkable liquid absorbing ratio of PVdF-HFP and the 3D cross-linking structure with semi-interpenetrating polymer network formed during UV-curing process. Unlabelled Image • We synthesized PVdF-HFP based gel polymer electrolytes by UV-curing method. • The electrolyte possesses both high ionic conductivity and mechanical strength. • The gel polymer electrolyte delivers high reversible lithium storage capacity. • The gel polymer electrolyte exhibits superior rate performance. [ABSTRACT FROM AUTHOR]

Emerging pollutants represent a new global problem for water quality. As these compounds get into the environment, they cause severe threats to aquatic environments and human health and are typically resistant to conventional wastewater treatments. In this work, TiO 2 nanoparticles surface was functionalized with silver (Ag) nanoparticles, and solvent cast and electrospun membranes of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) were prepared with different concentrations of TiO 2 and Ag–TiO 2 to produce a multifunctional material. The photocatalytic activity of the nanocomposites was evaluated through the degradation of norfloxacin under ultraviolet (UV) and visible radiation. It is shown that nanocomposites with Ag–TiO 2 show the highest degradation efficiencies: 64.2% under UV and 80.7% under visible radiation, for 90 and 300 min, respectively. Furthermore, the recyclability of the membranes has also been demonstrated. Finally, it is shown the antimicrobial activity of the nanocomposite membranes, demonstrating the suitability of the Ag–TiO 2 /PVDF-HFP nanocomposites as multifunctional photocatalytic and antimicrobial membranes for water remediation applications. Image 1 • Synthesis of Ag–TiO 2 nanocomposites with ability to absorb visible radiation. • Production of Ag–TiO 2 /PVDF-HFP membranes with different morphologies. • Photocatalytic efficiency tested with norfloxacin under visible and UV radiation. • Antimicrobial tests were performed against two bacteria species (gram + and gram -). [ABSTRACT FROM AUTHOR]

Flexible film with both piezoelectric and dielectric properties is considered to be a potential candidate for the energy conversion and storage devices. In this study, the Li+ and H2O modified sepiolite/poly(vinylidene fluoride‐co‐hexafluoropropylene) (LiSEP‐H2O/PVDF‐HFP) composite films with both good piezoelectric and dielectric properties were prepared by traditional coating process. When the H2O content was 13 wt %, the LiSEP‐H2O/PVDF‐HFP composite exhibited high d33 of 32 and dielectric constant of 48. Moreover, the effects of the Li+ and adsorbed H2O on the d33, F(β), dielectric constant, short‐circuit currents were discussed. The adsorbed H2O enhanced the β‐phase by the hydrogen bonds and Li+ improved the polarization to realize the composite film with increased piezoelectric and dielectric properties respectively. We expected the common modification to lead other clay minerals realizing the future applications in the adjustment of composites' electric properties. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48412. [ABSTRACT FROM AUTHOR]

Sulfide-based composite solid-state electrolyte has been deemed as "Holy Grail" for unlocking solid-state lithium metal batteries (SSLMBs) with high-energy density, combining the extremely high ionic conductivity of sulfide and machinability of organic polymer. However, this appealing system is hitherto stymied by two hindrances, difficult to synthesize due to the chemical incompatibility of sulfide with moisture and polar solvents, moreover, interfacial instability with lithium (Li) anode inducing severe Li dendrite grown. Herein, by utilizing perfluoropolyethers as bifunctional adjuvant, we initiatively fabricate sulfide-based composite electrolyte, Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/Li 10 GeP 2 S 12 and assemble SSLMBs. Perfluoropolyethers with low molecular weight facilitate the stable dispersion of Li 10 GeP 2 S 12 in casting solution, ascribed to their strong electronegativity of C–F bonds. In addition, high molecular weight perfluoropolyethers function as interfacial stabilizer, dramatically improving the interfacial compatibility with Li anode by in-situ forming a LiF-rich solid electrolyte interphase layer. This composite electrolyte exhibits high room temperature ionic conductivity (0.18 mS cm−1), outstanding lithium ion transfer number (0.68), good mechanical strength and nonflammability. The solid-state LiFePO 4 ǁLi battery presents superior long-term cycling stability and rate capability. Our study paves a new way for fabricating the sulfide-based composite electrolyte, provides an effective strategy for constructing compatible solid-state electrolyteǁLi interface. Image 1 • PVDF-HFP/Li 10 GeP 2 S 12 electrolyte is prepared by binary solution casting method. • PFPE 500 as dispersing solvents exhibit good chemical compatibility with Li 10 GeP 2 S 12. • A high ion conductivity (σ RT = 10−4 S cm−1) and Li+ transfer number (0.68) are obtained. • PFPEs as interfacial stabilizers enhance the compatibility of Li 10 GeP 2 S 12 with Li. • LiFePO 4 ‖Li battery shows good cycling stability and rate capability. [ABSTRACT FROM AUTHOR]

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.

The dendrite growth of Li anodes severely degrades the performance of lithium-oxygen (Li-O 2 ) batteries. Recently, hybrid solid electrolyte (HSE) has been regarded as one of the most promising routes to tackle this problem. However, before this is realized, the HSE needs to simultaneously satisfy contradictory requirements of high modulus and even, flexible contact with Li anode, while ensuring uniform Li + distribution. To tackle this complex dilemma, here, an HSE with rigid Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) core@ultrathin flexible poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) shell interface has been developed. The introduced large amount of nanometer-sized LAGP cores can not only act as structural enhancer to achieve high Young's modulus but can also construct Li + diffusion network to homogenize Li + distribution. The ultrathin flexible PVDF-HFP shell provides soft and stable contact between the rigid core and Li metal without affecting the Li + distribution, meanwhile suppressing the reduction of LAGP induced by direct contact with Li metal. Thanks to these advantages, this ingenious HSE with ultra-high Young's modulus of 25 GPa endows dendrite-free Li deposition even at a deposition capacity of 23.6 mAh. Moreover, with the successful inhibition of Li dendrites, the HSE-based quasi-solid-state Li-O 2 battery delivers a long cycling stability of 146 cycles, which is more than three times that of gel polymer electrolyte-based Li-O 2 battery. This new insight may serve as a starting point for further designing of HSE in Li-O 2 batteries, and can also be extended to various battery systems such as sodium-oxygen batteries., (© The Author(s) 2020. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

• Efficient, in-situ poled, ZnFe 2 O 4 nanorods and PVDF-HFP based flexible piezoelectric nanogenerator (HFNG) was developed. • Incorporation of in-plane oriented ZnFe 2 O 4 nanorods assists in all-trans extended β-polymorph transformation of PVDF-HFP. • HFNG can harvest electrical power from mechanical impact with power density 3.41 μW/mm3 to enlighten 21 red LEDs. • HFNG exhibited capability to monitor height with accuracy level up to ±3 cm. • Moreover, HFNG can scavenge electricity from environmental perturbation such as air flow and muscular vibrations. Herein, an efficient, low-cost, scalable in-situ poled fabrication strategy to construct a large area, highly sensitive, flexible piezocomposite nanogenerator comprising of rod shaped Zinc Ferrite (ZF-R) and Poly(vinylidene fluoride- co -hexafluoropropylene) (PVDF-HFP) was developed. ZF-R with an average length of 330 nm was synthesized via a facile two-pot hydrothermal method and its PVDF-HFP-based composites with different weight ratio were prepared. Fabricated 3 wt% ZF-R incorporated PVDF-HFP flexible piezocomposite (3H) was used as an effective nanogenerator which could generate an output voltage of 8.5 V and current density ∼0.5 μA/cm2 upon repetitive mechanical stresses. The generated power could enlighten 21 commercial light emitting diodes (LEDs). Furthermore, 3H demonstrated the capability to monitor height with level of accuracy upto ±3 cm. Moreover, this flexible hybrid film can scavenge environmental sensations such as air flow (maximum 3.2 V peak to peak voltage) and muscular vibration when integrated with arm, wrist and finger in conjunction with superior integratebility and nontoxicity. Thus, this nanocomposite can be explored for application as ultrasensitive height monitor, mechanical energy scavenger and effective power source for driving portable electronics and wearable devices. [ABSTRACT FROM AUTHOR]

To improve the thermal shrinkage and ionic conductivity of the separator for lithium-ion batteries, adding carboxylic titanium dioxide nanofiber materials into the matrix is proposed as an effective strategy. In this regard, a poly(vinylidene fluoride-hexafluoro propylene)/dibutyl phthalate/carboxylic titanium dioxide (PVDF-HFP/DBP/C-TiO2) composite separator is prepared with the phase inversion method. When the content of TiO2 nanofibers reaches 5%, the electrochemical performance of the battery and ion conductivity of the separator are optimal. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator shows about 55.5% of porosity and 277.9% of electrolyte uptake. The PVDF-HFP/DBP/C-TiO2 (5%) composite separator has a superior ionic conductivity of 1.26 × 10 −3 S cm−1 and lower interface impedance at room temperature, which brings about better cycle and rate performance. In addition, the cell assembled with a PVDF-HFP/DBP/C-TiO2 separator can be charged or discharged normally and has an outstanding discharge capacity of about 150 mAh g−1 at 110 °C. The battery assembled with the PVDF-HFP/DBP/C-TiO2 composite separator exhibits excellent electrochemical performance under high and room temperature environments. [ABSTRACT FROM AUTHOR]

Solid electrolytes for Li transport have been prepared by melt-compounding in one single step. Electrolytes are composed of polyvinylidene fluoride–hexafluoropropylene (PVDF–HFP) with PYR13TFSI on its own or with varying concentration of LiTFSI. While the extrusion of PVDF–HFP with PYR13TFSI is possible up to relatively high liquid fractions, the compatibility of PVDF–HFP with LiTFSI/PYR13TFSI solutions is much lower. An organo-modified sepiolite with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS-S) can be used to enhance the compatibility of these blends and allows to prepare homogeneous PYR13TFSI/LiTFSI/PVDF–HFP electrolytes with controlled microphase separations by melt-compounding. The structure and morphology of the electrolytes has been studied by FTIR, differential scanning calorimetry (DSC), SEM, and AFM. Their mechanical properties have been studied by classical strain–stress experiments. Finally, ionic conductivity has been studied in the −50 to 90 °C temperature range and in diffusivity at 25 °C by PFG-NMR. These electrolytes prove to have a microphase-separated morphology and ionic conductivity which depends mainly on their composition, and a mechanical behavior typical of common thermoplastic polymers, which makes them very easy to handle. Then, in this solvent-free and scalable fashion, it is possible to prepare electrolytes like those prepared by solvent casting, but in few minutes instead of several hours or days, without solvent evaporation steps, and with ionic conductivities, which are very similar for the same compositions, above 0.1 mS·cm−1 at 25 °C. In addition, some of the electrolytes have been prepared with high concentration of Li ion, what has allowed the anion exchange Li transport mechanism to contribute significantly to the overall Li diffusivity, making DLi become similar and even clearly greater than DTFSI. [ABSTRACT FROM AUTHOR]

Polyvinylidenefluoride-co-hexafluoropropylene(PVdF-HFP) and polymethylmethacrylate (PMMA) and sodium triflate(NaTf) were used to prepare P(VdF-HFP)-PMMA-NaTf electrolytes using solution casting technique. The liquid plasticizer ethylene carbonate (EC) was added to the electrolytes in different concentrations say 10, 20, 30 and 40 wt% to achieve the enhancement of Na+ ion conduction at room temperature. Ionic conductivity of the samples was determined using AC impedance analysis and it was 7.86 × 10−8 S cm−1 for the polymer blend electrolyte at room temperature. Inclusion of EC was found to enhance the Na+ ion conduction and maximum value of ionic conductivity, 1.86 × 10−4 S cm−1, was obtained for the EC concentration of 30 wt%. This observation was explained on the basis of FTIR, XRD and AFM analysis of the samples which revealed the enhanced EC-polymer interaction and hence fast ion transport. Larger increase of dielectric constants and the reduced dielectric loss of EC added polymer blend electrolytes revealed the increase of the number of free Na+ ions. Thermal analysis of the samples was done through TGA-DTG technique and the thermal stability was found to decrease after the addition of EC. [ABSTRACT FROM AUTHOR]

The polymers poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly(n-butyl methacrylate) (PBMA) are employed in manufacturing the XIENCE family of coronary stents. PBMA serves as a primer and adheres to both the stent and the drug coating. PVDF-HFP is employed in the drug matrix layer to hold the drug everolimus on the stent and control its release. Chemical stability of the polymers of XIENCE stents in the in-vivo environment was evaluated by pyrolysis-gas chromatography with mass spectrometry (Py-GC/MS) detection. For this evaluation, XIENCE stents explanted from porcine coronary arteries and from human coronary artery specimens at autopsy after 2-4 and 5-7 years of implantation, respectively, were compared to freshly manufactured XIENCE stents (controls). The comparison of pyrograms of explanted stent samples and controls showed identical fragmentation fingerprints of polymers, indicating that PVDF-HFP and PBMA maintained their chemical integrity after multiple years of XIENCE coronary stent implantation. The findings of the present study demonstrate the chemical stability of PVDF-HFP and PBMA polymers of the XIENCE family of coronary stents in the in-vivo environment, and constitute a further proof of the suitability of PVDF-HFP as a drug carrier for the drug eluting stent applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1721-1729, 2018., (© 2017 Wiley Periodicals, Inc.)

A poly(vinylidene fluoride-co-hexafluoropropylene)-based polymer inclusion membrane (PIM) using Cyphos® IL 101 (i.e. trihexyl(tetradecyl)phosphonium chloride) as the carrier and 2-nitrophenyl octyl ether as a plasticizer in a mass ratio of 55/35/10 was employed for the on-line extractive separation of V(V) prior to its spectrophotometric determination in a flow injection analysis (FIA) system using xylenol orange as the colorimetric reagent. The selectivity of the membrane allowed the determination of V(V) in sulfate solutions in the presence of a variety of cations and anions. The interference of molybdenum(VI) was eliminated by off-line extraction using the same PIM. A univariate sequential optimization of the newly developed FIA system was conducted and under optimal conditions the system is characterized by a linear concentration range of 0.5-8.0mgL -1 , detection limit of 0.08mgL -1 and sample throughput of 4h -1 . The relative standard deviation at the 3mgL -1 level of V(V) was 2.9% based on 8 replicate determinations. The membrane was stable, which was reflected by the standard deviation value for determinations over three consecutive days (24 determinations of 3mgL -1 V(V)) of 3.6%. The newly developed FIA system was applied to the determination of V(V) in water and dietary supplements samples and a good agreement with inductively coupled plasma optical emission spectrometry was observed., (Copyright © 2018 Elsevier B.V. All rights reserved.)

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.