Effect of different contents of organic-inorganic hybrid particles poly(methyl methacrylate) ZrO 2 on the properties of poly(vinylidene fluoride-hexafluoroprolene)-based composite gel polymer electrolytes

Efficient Improvement of Lithium Ionic Conductivity for Polymer Electrolyte via Introducing porous Metal–Organic Frameworks

Electrolyte membrane plays a vital role in the practical conduction application of lithium-ion batteries. In this study, a series of PVDF-HFP/MOF-5 composite electrolyte materials were harvested by incorporating MOF-5 into...

Significant improvement of the lithium-ion conductivity of solid-state electrolytes by fabricating large pore volume hollow ZIF-8

Metal-organic frameworks (MOFs) emerging as a type of functional material have been widely used in electrochemical energy storage and conversion in recent years. Hollow MOFs with a large pore volume and surface area can increase the contact area between active materials and electrolytes, thus improving the ionic conductivity of the materials. Herein, we obtained a kind of hollow MOF (ZIF-8) using carboxylate-terminated polystyrene microspheres as exterior templates. Transmission electron microscopy and N₂ adsorption/desorption analysis revealed that the average cavity diameter of hollow ZIF-8 is 1 μm. Moreover, hollow ZIF-8 exhibits excellent electrochemical quality with an ionic conductivity of 7.36 × 10^-4 S cm^-1, a lithium ion transference number of 0.83 and an activation energy of 0.15 eV in a wide stable electrochemical window of 2.0-6.5 V at room temperature. Compared with the traditional non-hollow ZIF-8, the electrochemical performance has been improved obviously. Consequently, our strategy of fabrication of large pore volume hollow MOFs provides a new perspective for the development of solid electrolytes with excellent lithium ionic conductivity.

Highly Stretchable and Transparent Optical Adhesive Films Using Hierarchically Structured Rigid-Flexible Dual-Stiffness Nanoparticles

The demand for new forms of flexible electronic devices has led to the evolution of individual components comprising optical adhesive films that provide excellent optical transparency and high bonding strength while offering remarkable elasticity with high strain and recovery properties. Herein, a new type of highly elastic and transparent adhesive film is proposed using tailored rigid-flexible dual-stiffness nanoparticles (DSNs) composed of a rigid inorganic core and an elastic reactive coil shell. The hierarchically structured nanoparticles were prepared from SiO₂ nanoparticles via the sequential surface modification with photoreactive flexible chains. The fabricated elastic adhesive film containing DSNs with an average diameter of 20 nm showed a high optical transmittance of 92% and adhesion strength of 19.9 N/25 mm. Increasing the content of the tailored nanoparticles in the adhesive film improved the elastic properties of the film such as elastic modulus (7.0 kPa), stress relaxation ratio (18.4%), and strain recovery rate (73.6%) due to the efficient elastic motion of the embedded DSNs. In addition, as the surface grafting density of elastic coil groups in the nanoparticle increased, a stronger bonding network was formed between the nanoparticles and the acrylic polymer matrix, thereby further improving the stress relaxation ratio (18.0%) and strain recovery rate (77.1%) of the optical film. Thus, the utilization of novel dual-stiffness nanoparticles produces optical adhesive films with high elasticity and optical transparency that are capable of withstanding external forces such as folding and stretching, which is essential for flexible electronic devices.

Optimization of the Electrochemical Performance of a Composite Polymer Electrolyte Based on PVA-K2CO3-SiO2 Composite

Composite polymer electrolyte (CPE) based on polyvinyl alcohol (PVA) polymer, potassium carbonate (K₂CO₃) salt, and silica (SiO₂) filler was investigated and optimized in this study for improved ionic conductivity and potential window for use in electrochemical devices. Various quantities of SiO₂ in wt.% were incorporated into PVA-K₂CO₃ complex to prepare the CPEs. To study the effect of SiO₂ on PVA-K₂CO₃ composites, the developed electrolytes were characterized for their chemical structure (FTIR), morphology (FESEM), thermal stabilities (TGA), glass transition temperature (differential scanning calorimetry (DSC)), ionic conductivity using electrochemical impedance spectroscopy (EIS), and potential window using linear sweep voltammetry (LSV). Physicochemical characterization results based on thermal and structural analysis indicated that the addition of SiO₂ enhanced the amorphous region of the PVA-K₂CO₃ composites which enhanced the dissociation of the K₂CO₃ salt into K⁺ and CO₃^2- and thus resulting in an increase of the ionic conduction of the electrolyte. An optimum ionic conductivity of 3.25 × 10^-4 and 7.86 × 10^-3 mScm^-1 at ambient temperature and at 373.15 K, respectively, at a potential window of 3.35 V was observed at a composition of 15 wt.% SiO₂. From FESEM micrographs, the white granules and aggregate seen on the surface of the samples confirm that SiO₂ particles have been successfully dispersed into the PVA-K₂CO₃ matrix. The observed ionic conductivity increased linearly with increase in temperature confirming the electrolyte as temperature-dependent. Based on the observed performance, it can be concluded that the CPEs based on PVA-K₂CO₃-SiO₂ composites could serve as promising candidate for portable and flexible next generation energy storage devices.

Resorcinol-Formaldehyde (RF) as a Novel Plasticizer for Starch-Based Solid Biopolymer Electrolyte

A starch-resorcinol-formaldehyde (RF)-lithium triflate (LiTf) based biodegradable polymer electrolyte membrane was synthesized via the solution casting technique. The formation of RF crosslinks in the starch matrix was found to repress the starch's crystallinity as indicated by the XRD data. Incorporation of the RF plasticizer improved the conductivity greatly, with the highest room-temperature conductivity recorded being 4.29 × 10-4 S cm-1 achieved by the starch:LiTf:RF (20 wt.%:20 wt.%:60 wt.%) composition. The enhancement in ionic conductivity was an implication of the increase in the polymeric amorphous region concurrent with the suppression of the starch's crystallinity. Chemical complexation between the plasticizer, starch, and lithium salt components in the electrolyte was confirmed by FTIR spectra.

Core-Shell Hybrid Nanowires with Protein Enabling Fast Ion Conduction for High-Performance Composite Polymer Electrolytes

Incorporating nanofillers is one of the promising approaches for simultaneously boosting the ionic conductivity and mechanical properties of solid polymer electrolytes (SPEs). However, effectively creating faster ion-conduction pathways via nanofillers still remains a big challenge. Herein, core-shell protein-ceramic nanowires for more efficiently building fast ion-conduction networks in SPEs are reported. The core-shell protein-ceramic nanowires are fabricated via in situ growth of protein coating on the electrospun TiO₂ nanowires in a subtly controlled protein-denaturation process. It is demonstrated that the core-shell protein@TiO₂ nanowires effectively facilitate ion-conduction. As a result, the ionic conductivity, mechanical properties, electrochemical stability, and even Li⁺ transference number of the SPEs with core-shell protein@TiO₂ nanowires are significantly enhanced. The contributions from the 1D morphology of the protein@TiO₂ nanowires, and more importantly, the favorable protein structure for further promoting ion-conduction at the polymer-filler interfaces are analyzed. It is believed that the protein plays a pivotal role in dissociating lithium salts, which benefits from the strong interactions between protein and ions, making the protein serve as a unique "natural channel" for rapidly conducting Li⁺ . This study initiates an effective method of promoting ionic conductivity and constructing faster ion-conduction networks in SPEs via combining bio- and nanotechnology.

High Performance Composite Polymer Electrolytes Doped With Spherical-Like and Honeycomb Structural Li0.1Ca0.9TiO3 Particles

The spherical-like and honeycomb structural Li_0.1Ca_0.9TiO₃ particles are prepared by spray drying combined with following calcination confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray spectrometer (EDS). The poly (vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP))-based composite polymer electrolytes (CPEs) modified with the particles are fabricated by phase inversion and activation processes. The characterization results show that the as-prepared CPE membranes possess the smoothest surface and most abundant micropores with the lowest crystallinity with adding the particles into the polymer matrix, which results in high ionic conductivity (3.947 mS cm^-1) and lithium ion transference number (0.4962) at ambient temperature. The interfacial resistance can be quickly stabilized at 508 Ω after 5 days storage and the electrochemical working window is up to 5.2 V. Moreover, the mechanical strength of the membranes gains significant improvement without lowering the ionic conductivity. Furthermore, the assembled coin cell can also deliver high discharge specific capacity and preserve steady cycle performance at different current densities. Those outstanding properties may be ascribed to the distinctive structure of the tailored spherical-like and honeycomb structural Li_0.1Ca_0.9TiO₃ particles, which can guarantee the desirable CPEs as a new promising candidate for the polymer electrolyte.