With the increase of interest in the application of piezoelectric polyvinylidene fluoride (PVDF) in nanogenerators (NGs), sensors, and microdevices, the most efficient and suitable methods of their synthesis are being pursued. Electrospinning is an effective method to prepare higher content β-phase PVDF nanofiber films without additional high voltage poling or mechanical stretching, and thus, it is considered an economically viable and relatively simple method. This work discusses the parameters affecting the preparation of the desired phase of the PVDF film with a higher electrical output. The design and selection of optimum preparation conditions such as solution concentration, solvents, the molecular weight of PVDF, and others lead to electrical properties and performance enhancement in the NG, sensor, and other applications. Additionally, the effect of the nanoparticle additives that showed efficient improvements in the PVDF films was discussed as well. For instance, additives of BaTiO3, carbon nanotubes, graphene, nanoclays, and others are summarized to show their contributions to the higher piezo response in the electrospun PVDF. The recently reported applications of electrospun PVDF films are also analyzed in this review paper.

Currently, different metal sulfides (NiS, Co 9 S 8 , FeS 2 , and CuS) have been extensively studied as alternative electrodes for rechargeable batteries that can satisfy the performance requirements for more powerful energy supply and storage technologies for various applications and industries. Among them, copper sulfides have gained significant attention as a promising electrode material in rechargeable metal-ion (Li, Mg, Na, and Al) batteries. A wide range of synthesis routes and methods have been implemented in order to prepare various stoichiometry Cu x S (1 ≤ x ≤ 2) micro-/nanostructured materials with excellent electrochemical properties. Since the bulk microsized electrode materials have almost reached their performance limits for energy devices, the introduction of nanoscale Cu x S composites is now in high demand. This review focuses on the influence of the material morphology and dimensions on their performance in secondary batteries. The structures of Cu x S materials from zero-dimensional (0D) to 3D and their preparation are discussed. The primary purpose of this work is to provide an overview of the unique electrochemical and physical properties of particular structure and dimensionality which can promote these materials' application in the energy storage field. Along with this, this work summarizes the information on various synthesis strategies and how they can manage the morphologies of Cu x S micro-/nanocomposites. In the current fast technologically advancing society, the development of the most economically profitable and efficient synthesis routes is especially encouraged and required, and this aspect is also commented on in this review.

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We investigated the effect of epicyanohydrin as an additive to a LiPF6 salt–based electrolyte in 1:1:1 EC:EMC:DMC for high-power lithium-ion batteries operated at 60°C. Epicyanohydrin polymerized to form a thermally stable, thin, conductive, and evenly distributed protective film on the cathode surface, preventing dissolution of the cathode material LiNi0.6Co0.2Mn0.2O2 and suppressing interfacial impedance, thereby protecting the surface from further reaction with the electrolyte at 60°C. The cycling performance of the cathode materials with the additive was enhanced due to the formation of an epicyanohydrin-derived polymer solid electrolyte interface (SEI).

This work reports the preparation of a three‐dimensional Si thin film negative electrode employing a porous Cu current collector. A previously reported copper etching procedure was modified to develop the porous structures inside a 9 μm thick copper foil. Magnetron sputtering was used for the deposition of an n‐type doped 400 nm thick amorphous Si thin film. Electrochemical cycling of the prepared anode confirmed the effectiveness of utilizing the approach. The designed Si thin film electrode retained a capacity of around 67 μAh cm−2 (1675 mAh g−1) in 100th cycle. The improved electrochemical performance resulted in an enhancement of both areal capacity and capacity retention in contrast with flat and rough current collectors that were prepared for comparison.

The synergistic strategy combining architectural design with defect engineering in transition-metal sulfides offers a promising opportunity to realize high-efficiency polysulfide adsorption/conversion surface catalysis in lithium/sulfur (Li/S) batteries. Here, defect-rich yolk–shell hollow spheres composed of ultrafine NiCo2S4–x nanoparticles as sulfur hosts prepared by an anion-exchange method are reported. The elaborate design of sulfur defects endows the NiCo2S4–x hollow spheres with significantly enhanced electronic conductivity and superior affinity for polysulfides as well as expedited sulfur conversion. Meanwhile, the unique yolk–shell NiCo2S4–x hollow sphere structure provides large cavities that not only increase sulfur storage but also relieve the electrode volume expansion during cycling. Combining these favorable features, the NiCo2S4–x -hosted sulfur cathode revealed enhanced cycling stability, corresponding to a negligible capacity fading rate of 0.0754% per cycle after 500 cycles at 1 C, and achieved an outstanding rate capability (628.9 mAh g–1 up to 5 C).

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