Fibre reinforcement of elastomers: nanocomposites based on sepiolite and poly(hydroxyethyl acrylate)

Recent Progress on Natural Clay Minerals for Lithium-Sulfur Batteries

Li-S batteries with high energy density have the potential to become a viable alternative to Li-ion batteries. However, Li-S batteries still face several challenges, including the shuttle effect, low conversion kinetics, and Li dendrite growth. Natural clay minerals with porous structures, abundant Lewis-acid sites, high mechanical modulus, and versatile structural regulation show great potential for improving the performance of Li-S batteries. However, so far, relevant reviews focusing on the applications of natural clay minerals in Li-S batteries are still missing. To fill the gap, this review first presents an overview of the crystal structures of several natural clay minerals, including 1D (halloysites, attapulgites, and sepiolite), 2D (montmorillonite and vermiculite), and 3D (diatomite) structures, providing a theoretical basis for the application of natural clay minerals in Li-S batteries. Subsequently, research advancements in the natural clay-based energy materials in Li-S batteries have been comprehensively reviewed. Finally, the perspectives concerning the development of natural clay minerals and their applications in Li-S batteries are provided. We hope this review can provide timely and comprehensive information on the correlation between the structure and function of natural clay minerals in Li-S batteries and offer guidance for material selection and structure optimization of natural clay-based energy materials.

Effect of Polyaniline on Sulfur/Sepiolite Composite Cathode for Lithium-Sulfur Batteries

Composite materials with a stable network structure consisting of natural sepiolite (Sp) powders (both sieved sepiolite and post-treated sepiolite), sulfur(S), and conductive polymer Polyaniline (PAni) have been successfully synthesized using a simple heat treatment. The morphology of composites illustrates that the sepiolite is composed of many needle-like fibrous clusters. The initial discharge capacity of the post-treated sepiolite/sulfur/PAni composite is about 1230 mA h g-1 at 0.1 C, and it remains at 826 mA h g-1 even after 40 cycles with the corresponding coulombic efficiency above 97%. Such performance is attributed to the specific porous structure, outstanding adsorption characteristics, and excellent ion exchange capability of sepiolite, as well as the excellent conductivity of PAni. In addition, the PAni coating has a pinning effect on sulfur, which influences the consumption of the active mass and enhances the cycling constancy and the coulombic efficiency of the composite material at elevated current rates.

Effect of Acid Activation-Hydrophilic-Modified Sepiolite on Comprehensive Properties of Oil-Well Cement

In this paper, sepiolite was treated by acid activation, coupling agent treatment, and sulfonation modification. The purpose of this study was to explore the changes in the fluidity and mechanical properties of sepiolite cement slurry before and after modification. Therefore, the comprehensive properties of unmodified sepiolite fiber (HPS) and acid activation-coupling agent treatment-sulfonated sepiolite fiber (S-O-H-HPS) in oil-well cement slurry were evaluated. FT-IR and microscopic mechanism of cement paste fracture surface before and after sepiolite modification were analyzed. The results showed that HPS can effectively improve the toughness of cement paste, but when the content of HPS was more than 1%, the fluidity of cement paste deteriorated sharply and the compressive strength decreased gradually. The addition of S-O-H-HPS can significantly improve the fluidity and stability of HPS slurry. Without affecting the compressive strength, it can effectively improve the flexural strength and impact strength and reduce the elastic modulus of cement paste. The mechanism analysis showed that S-O-H-HPS can not only form network structure in cement paste but also improve the toughness of cement paste by forming a bridge. This also explains why the strength of S-O-H-HPS cement paste does not decrease significantly with the increase of S-O-H-HPS.

Chlorinated polyethylene (CPE)/ethylene methacrylate copolymer (EMA)/sepiolite nanocomposite via a facile one-step covalent modification technique

Facile one-step organo-modification of sepiolite improves polymer–filler interfacial adhesion, thereby advances mechanical properties and thermal stability of the CPE/EMA/sepiolite nanocomposite.

Surface modification of sepiolite in aqueous gels by using methoxysilanes and its impact on the nanofiber dispersion ability

Surface modification reactions on needle-like sepiolite using alkyl and functional silanes have been carried out in the form of aqueous gels. In contrast with modifications in organic solvents, reactions in water make it possible to modify the surface of almost-individual sepiolite fibers and produce either a continuous coating or a nanotexturization of the sepiolite fiber surface, depending on the reaction conditions. This clean procedure substitutes advantageously organic solvent surface modifications and allows the tuning of surface properties such as specific surface area, wetting behavior, and chemical functionalization. A consequence of such tuning is, for example, the excellent dispersion of modified sepiolite nanofibers in a great variety of polymers by routine compounding and processing techniques.