Synthesis and application of epoxy resins: A review

Sodium-ion batteries (SIBs) receive significant attention for electrochemical energy storage and conversion owing to their wide availability and the low cost of Na resources. However, SIBs face challenges of low specific energy, short cycling life, and insufficient specific power, owing to the heavy mass and large radius of Na(+) ions. As an important component of SIBs, cathode materials have a significant effect on the SIB electrochemical performance. The most recent advances and prospects of inorganic and organic cathode materials are summarized here. Among current cathode materials, layered transition-metal oxides achieve high specific energies around 600 mW h g(-1) owing to their high specific capacities of 180-220 mA h g(-1) and their moderate operating potentials of 2.7-3.2 V (vs Na(+) /Na). Porous Na3 V2 (PO4 )3 /C nanomaterials exhibit excellent cycling performance with almost 100% retention over 1000 cycles owing to their robust structural framework. Recent emerging cathode materials, such as amorphous NaFePO4 and pteridine derivatives show interesting electrochemical properties and attractive prospects for application in SIBs. Future work should focus on strategies to enhance the overall performance of cathode materials in terms of specific energy, cycling life, and rate capability with cationic doping, anionic substitution, morphology fabrication, and electrolyte matching.

Recent Advances and Prospects of Cathode Materials for Sodium‐Ion Batteries

Grid-scale energy storage systems (ESSs) that can connect to sustainable energy resources have received great attention in an effort to satisfy ever-growing energy demands. Although recent advances in Li-ion battery (LIB) technology have increased the energy density to a level applicable to grid-scale ESSs, the high cost of Li and transition metals have led to a search for lower-cost battery system alternatives. Based on the abundance and accessibility of Na and its similar electrochemistry to the well-established LIB technology, Na-ion batteries (NIBs) have attracted significant attention as an ideal candidate for grid-scale ESSs. Since research on NIB chemistry resurged in 2010, various positive and negative electrode materials have been synthesized and evaluated for NIBs. Nonetheless, studies on NIB chemistry are still in their infancy compared with LIB technology, and further improvements are required in terms of energy, power density, and electrochemical stability for commercialization. Most recent progress on electrode materials for NIBs, including the discovery of new electrode materials and their Na storage mechanisms, is briefly reviewed. In addition, efforts to enhance the electrochemical properties of NIB electrode materials as well as the challenges and perspectives involving these materials are discussed.

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Recent Progress in Electrode Materials for Sodium-Ion Batteries

Unperturbed dimensions of stereoregular polymers.- Reinforcement of rubber by carbon black.- Transformations of phenolic antioxidants and the role of their products in the long-term properties of polyolefins.

Properties of polymers

Organic electrode materials are very attractive for electrochemical energy storage devices because they can be flexible, lightweight, low cost, benign to the environment, and used in a variety of device architectures. They are not mere alternatives to more traditional energy storage materials, rather, they have the potential to lead to disruptive technologies. Although organic electrode materials for energy storage have progressed in recent years, there are still significant challenges to overcome before reaching large-scale commercialization. This review provides an overview of energy storage systems as a whole, the metrics that are used to quantify the performance of electrodes, recent strategies that have been investigated to overcome the challenges associated with organic electrode materials, and the use of computational chemistry to design and study new materials and their properties. Design strategies are examined to overcome issues with capacity/capacitance, device voltage, rate capability, and cycling stability in order to guide future work in the area. The use of low cost materials is highlighted as a direction towards commercial realization.

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The rise of organic electrode materials for energy storage

2,6-Dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4-methylbenzenamine Nickel Dibromides: Synthesis, Characterization, and Ethylene Polymerization

A type of polyurethane elastomer with excellent self-healing ability has been fabricated through digital light processing 3D printing. First, a type of polyurethane acrylate containing disulfide bo...

Self-Healing Polyurethane Elastomers Based on a Disulfide Bond by Digital Light Processing 3D Printing

Four-dimensional printing, a new process to fabricate active materials through three-dimensional (3D) printing developed by MIT’s Self-Assembly Lab in 2014, has attracted more and more research and development interests recently. In this paper, a type of epoxy-acrylate hybrid photopolymer was synthesized and applied to fabricate shape memory polymers through a stereolithography 3D printing technique. The glass-to-rubbery modulus ratio of the printed sample determined by dynamic mechanical analysis is as high as 600, indicating that it may possess good shape memory properties. Fold-deploy and shape memory cycle tests were applied to evaluate its shape memory performance. The shape fixity ratio and the shape recovery ratio in ten cycles of fold-deploy tests are about 99 and 100%, respectively. The shape recovery process takes less than 20 s, indicating its rapid shape recovery rate. The shape fixity ratio and shape recovery ratio during 18 consecutive shape memory cycles are 97.44 ± 0.08 and 100.02 ± 0.05%,...

Three-Dimensional Printing of Shape Memory Composites with Epoxy-Acrylate Hybrid Photopolymer.

A new high performance stiff epoxy vitrimer based on siloxane equilibration has been fabricated in a simple way in which a polysiloxane oligomer containing aminopropyl side groups and catalytic potassium silanolate end groups was synthesized and used as a curing agent. The viscoelastic properties of the cured epoxy can be controlled by varying the concentration of potassium silanolate groups and the vitrimer possessing a complete stress relaxation behavior can be prepared, with relaxation times ranging from 376.8 s at 90 °C to 40.2 s at 170 °C. Due to the dynamic siloxane equilibration of polysiloxane catalyzed by potassium silanolate groups, this epoxy vitrimer exhibits excellent self-healing and recycling abilities. It can self-repair with a high healing efficiency, and be recycled at 130 °C within 40 min, retaining its original mechanical and thermal properties after at least four recycling cycles. Furthermore, such a material exhibits simultaneously a high service temperature (a glass transition temperature of 83 °C and an initial degradation temperature of 358 °C) and a strong (a stress at break of 46.6 MPa) and stiff (Young's modulus of 2.2 GPa) nature.

A facile access to stiff epoxy vitrimers with excellent mechanical properties via siloxane equilibration

Conjugated microporous polymers, which exhibit high specific capacity, superior cycle stability and remarkable rate capability, are explored as high-performance electrode materials for lithium and sodium storage. Their excellent electrochemical performance can be attributed to their conductive frameworks, plentiful redox-active units, high specific surface area and homogeneous microporous structure.

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Wei Huang

Papers

2,6-Dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-4-methylbenzenamine Nickel Dibromides: Synthesis, Characterization, and Ethylene Polymerization

Self-Healing Polyurethane Elastomers Based on a Disulfide Bond by Digital Light Processing 3D Printing

Three-Dimensional Printing of Shape Memory Composites with Epoxy-Acrylate Hybrid Photopolymer.

A facile access to stiff epoxy vitrimers with excellent mechanical properties via siloxane equilibration

Conjugated microporous polymers with excellent electrochemical performance for lithium and sodium storage