A novel PVB based polymer membrane and its application in gel polymer electrolytes for lithium-ion batteries

A Bionic Skin for Health Management: Excellent Breathability, In Situ Sensing, and Big Data Analysis

Developing an intelligent wearable system is of great significance to human health management. An ideal health-monitoring patch should possess key characteristics such as high air permeability, moisture-wicking function, high sensitivity, and a comfortable user experience. However, such a patch that encompasses all these functions is rarely reported. Herein, an intelligent bionic skin patch for health management is developed by integrating bionic structures, nano-welding technology, flexible circuit design, multifunctional sensing functions, and big data analysis using advanced electrospinning technology. By controlling the preparation of nanofibers and constructing bionic secondary structures, the resulting nanofiber membrane closely resembles human skin, exhibiting excellent air/moisture permeability, and one-side sweat-wicking properties. Additionally, the bionic patch is endowed with a high-precision signal acquisition capabilities for sweat metabolites, including glucose, lactic acid, and pH; skin temperature, skin impedance, and electromyographic signals can be precisely measured through the in situ sensing electrodes and flexible circuit design. The achieved intelligent bionic skin patch holds great potential for applications in health management systems and rehabilitation engineering management. The design of the smart bionic patch not only provides high practical value for health management but also has great theoretical value for the development of the new generation of wearable electronic devices.

Macromolecular Design of Lithium Conductive Polymer as Electrolyte for Solid-State Lithium Batteries

In the development of solid-state lithium batteries, solid polymer electrolyte (SPE) has drawn extensive concerns for its thermal and chemical stability, low density, and good processability. Especially SPE efficiently suppresses the formation of lithium dendrite and promotes battery safety. However, most of SPE is derived from the matrix with simple functional group, which suffers from low ionic conductivity, reduced mechanical properties after conductivity modification, bad electrochemical stability, and low lithium-ion transference number. Appling macromolecular design with multiple functional groups to polymer matrix is accepted as a strategy to solve the problems of SPE fundamentally. In this review, macromolecular design based on lithium conducting groups is summarized including copolymerization, network construction, and grafting. Meanwhile, the construction of single-ion conductor polymer is also focused herein. Moreover, synergistic effects between the designed matrix, lithium salt, and fillers are reviewed with the objective to further improve the performance of SPE. At last, future studies on macromolecular design are proposed in the development of SPE for solid-state batteries with high energy density and durability.

Preparation and application of a high-temperature–resistant EVOH-SO3Li/PI fiber membrane with self-closing pores

A lithium ethylene-vinyl alcohol copolymer sulfate (EVOH-SO3Li)/polyimide (PI) composite fiber membrane prepared via high-voltage electrospinning and impregnation was used as a lithium-ion battery separator for research purposes. The polyamic acid spinning solution was synthesized from 3,3′′,4,4′′-benzophenone tetracarboxylic dianhydride and 4,4-diaminodiphenyl ether. The PI fiber membrane was prepared via high-voltage electrospinning and thermal imidization, and EVOH-SO3Li was then coated on the surface of the PI fiber to prepare an EVOH-SO3Li/PI composite fiber membrane material (t-EVOH-SO3Li/PI). Overall, the EVOH-SO3Li/PI membrane exhibits excellent basic physical properties, given the clear three-dimensional network microstructure. When compared with EVOH-SO3Li/PI composite fiber membrane prepared via the cospinning method (s-EVOH-SO3Li/PI), its electrolyte uptake and tensile strength can increase to 739% and 17.56 MPa, respectively. Additionally, the EVOH-SO3Li/PI composite fiber membrane prepared via high-voltage electrospinning and impregnation exhibits better heat shrinkage stability, electrochemical performance, and high-temperature self-closing pores function. The electrochemical stability window, electrochemical impedance, and ionic conductivity correspond to 5.8 V, 310 Ω, and 3.753 × 10−3 S cm−1, respectively. Specifically, at 200°C, the internal pores can close effectively, and this is extremely important for the safety of lithium-ion batteries.

Preparation of SnO2 nanotubes via a template-free electrospinning process

A facile and environmentally friendly template-free method is developed for the fabrication of SnO2 nanotubes via electrospinning and precisely controlled heat treatment method. It is revealed that the as-spun solid SnO2 precursor fibers gradually transformed into hollow-structured nanotubes when the temperature was controlled precisely from 200 °C to 600 °C. It was confirmed, that this remarkable structural evolution corporate the respective thermal decomposition of polyvinyl butyral (PVB) at the surface and inside of the fibers. The formation mechanism of the nanotubes has been clarified by systematically investigating the morphology, phase structure, chemical state, and decomposition of the organic compounds during the heat treatment. The as-prepared SnO2 nanotubes exhibit a high specific surface area of 32.91 m2 g-1 and a porous structure with pore sizes of 2 nm and 10-25 nm. The SnO2 nanotubes were assembled as a photosensor, which demonstrates a fast response upon UV light illumination at 254 nm. From this discovery, it is expected that a new method for fabricating nanotubes will be established and the development of materials with a higher functionality will be promoted.

Consolidation of Fir Wood by Poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) Treatment: Study of Surface and Mechanical Characteristics

The ability of poly(vinyl butyral-co-vinyl alcohol-co-vinyl acetate) (PVBVA) to consolidate Fir wood was studied in terms of the surface and mechanical properties' changes. Two variables were considered to treat the wood: (i) the concentration (5 and 10 wt.%) of PVBVA solutions and (ii) the method of application (brushing and immersion). The presence of PVBVA on the wood surfaces was confirmed by infrared spectroscopy. Surface roughness measured by optical profilometry did not reveal changes in the topography of the samples, and appropriate visual appearance was confirmed. Contact angle measurements showed that a droplet of the 10%-PVBVA solution needed 50 s to reach the same contact angle decreasing rate as that measured for the 5%-PVBVA solution, suggesting there was some kind of induction time till the spreading process was no longer controlled by the viscosity, but by the solution-wood interactions. Water contact angle (WCA) measurements proved a more hydrophobic surface of the PVBVA-treated samples, compared to untreated wood. Mechanical characterization of the samples was done macroscopically by a three-point bending test and locally by the Shore D and Martens hardness (MH). Only results from MH experiments provided comparative results, indicating that treatment with PVBVA solutions increased wood hardness locally, being enhanced with solution concentration. The best surface mechanical properties were obtained for the samples immersed in the 10%-PVBVA solution.

A Review on Inorganic Nanoparticles Modified Composite Membranes for Lithium-Ion Batteries: Recent Progress and Prospects

Separators with high porosity, mechanical robustness, high ion conductivity, thin structure, excellent thermal stability, high electrolyte uptake and high retention capacity is today's burning research topic. These characteristics are not easily achieved by using single polymer separators. Inorganic nanoparticle use is one of the efforts to achieve these attributes and it has taken its place in recent research. The inorganic nanoparticles not only improve the physical characteristics of the separator but also keep it from dendrite problems, which enhance its shelf life. In this article, use of inorganic particles for lithium-ion battery membrane modification is discussed in detail and composite membranes with three main types including inorganic particle-coated composite membranes, inorganic particle-filled composite membranes and inorganic particle-filled non-woven mates are described. The possible advantages of inorganic particles application on membrane morphology, different techniques and modification methods for improving particle performance in the composite membrane, future prospects and better applications of ceramic nanoparticles and improvements in these composite membranes are also highlighted. In short, the contents of this review provide a fruitful source for further study and the development of new lithium-ion battery membranes with improved mechanical stability, chemical inertness and better electrochemical properties.

Exploring PVFM-Based Janus Membrane-Supporting Gel Polymer Electrolyte for Highly Durable Li-O2 Batteries

Electrolyte is the key to constructing the ionic transport paths and O₂ gas diffusion routes in the cathode as well as maintaining the electrode interfacial stability in view of the complex chemistry of Li-O₂ batteries. A novel poly(vinyl formal) (PVFM)-based Janus membrane, which is prepared via coating multiwalled carbon nanotubes (MWCNTs) on the porous side of the cross-linked PVFM membrane, has been proposed herein to achieve membrane-supporting gel polymer electrolyte (GPE) for Li-O₂ batteries. Within Li-O₂ batteries, the dense side of PVFM-based Janus membrane demonstrates a good compatibility with lithium metal anode, while the other side with MWCNTs coating reserves much more solvent on the surface, assisting the cathode to form enlarged electrolyte-wetted interface. Moreover, the comparative studies indicate that PVFM-based Janus membrane also can provide a conductive pathway, modulate the morphology of the discharge products, and produce accommodation space for the products. So, the Li-O₂ batteries containing PVFM-based Janus membrane-supporting GPE not only demonstrate significantly improved discharge capacity and cycling stability, i.e., 150 times at 1000 mAh g^-1 capacity limitation, but also a narrow voltage gap of 0.90 V and an excellent rate performance up to 1000 mA g^-1.

Thermally induced chemical cross-linking reinforced fluorinated polyurethane/polyacrylonitrile/polyvinyl butyral nanofibers for waterproof-breathable application

Thermally induced chemical cross-linking could enhance the FPAN/PVB/BIP composite nanofibrous membranes with robust mechanical, waterproof and breathable performance.

Progress in polymeric separators for lithium ion batteries

This study reviews the recent developments and the characteristics of polymeric separators used for lithium ion batteries.