The incorporation of polar monomers in copolymers based on styrene and divinylbenzene obtained from glycerol suspension polymerization

Porous copolymer networks based on styrene (STY) and divinylbenzene (DVB) containing polar monomer (methacrylamide — MAM, methacrylic acid — MAA or acrylonitrile — ACN) were prepared by suspension polymerization using glycerol as a dispersant medium. Poly(styrene-co-methacrylamide-co-divinylbenzene), poly(styrene-co-methacrylic acid-co-divinylbenzene) and poly(styrene-co-acrylonitrile-co-divinylbenzene) were synthesized using mixtures of toluene with 2-butanone, toluene and 2-butanone and n-heptane with ethylacetate, respectively at different dilutions: 50%, 100% and 120% (v/v). The copolymers were characterized by bulk density, infrared spectrometry (FTIR) and elemental analysis (CHN). Morphological features of the copolymer pearls were evaluated by microscopic analysis and correlations between porous structure and parameters of reaction were found. The copolymers presented high incorporation of polar monomers. The pearl porosities and visual appearances had a strict relation with the monomer type and the dilution degree employed in synthesizing them.     

膨胀石墨基镍/炭复合物(英文)

NiO粒子修饰的压缩膨胀石墨(EGNiO)浸以煤焦油沥青,经550℃裂解,继而800℃水蒸气活化,制得Ni/C复合物块体。应用TEM考察了复合物中含Ni纳米粒的微结构排列方式。以N2吸附测定分析了复合物的比表面积和孔隙度。以2,2,3—三甲基戊烷脱氢裂解模型反应评估了复合物的催化活性并与EGNiO常规H2处理获得的参照物的活性做了比较。     

锂离子二次电池负极材料的研究综述

总结了在碳材料、合金材料和复合材料等3个锂离子电池负极材料研发的主导方向上的开发情况和它们各自特点,描述了目前的研究所面临难题,给出了锂离子电池负极材料研发取得重大突破的可能途径和建议.     

纳米硅/石墨负极材料的炭包覆改性研究

硅颗粒的低负载量及其与石墨基体的弱相互作用严重制约了硅/石墨负极材料的商业化应用.本研究通过浓硫酸和高锰酸钾的氧化处理增大石墨基体的比表面积,利用十二烷基苯磺酸钠作为表面活性剂,改善纳米硅与氧化石墨湿法混合的均匀性,采用柠檬酸催化蔗糖碳源的水解,以便热解后在复合材料表面形成完整的炭包覆层.XRD与SEM分析表明,改进的...     

Carbon based electronic materials: applications in electron field emission

The influence of the different types of bonding present in a range of carbon based materials is discussed as a precursor to describing the field emission characteristics of carbon cold cathode materials. Some of the controlling factors which govern electron emission from carbon based cathodes are discussed. It is shown that from disordered carbon films the interplay between the clustered sp² phase and the insulating sp³ matrix is important. The transition from a ‘back contact’ to ‘front surface’ controlled emission mechanism is described in terms of the sp² content and field penetration. A possible reason for high field enhancement factors found in disordered films also is provided. It is further shown that changes to the sp² phase by current stressing can improve the field emission characteristics. Emission from carbon nanotubes is also discussed and the prospects for new types of nanotube – polymer composite based cathodes are also considered.     

Progress and perspectives on alloying-type anode materials for advanced potassium-ion batteries

Potassium-ion batteries (PIBs) have attracted increasing interest as promising alternatives to lithium-ion batteries (LIBs) for application in large-scale electrical energy storage systems (EESSs) owing to a wide earth-abundance, potential price advantages, and low standard redox potential of potassium. Developmental materials for use in PIBs that can yield high specific capacities and durability are widely sought with emerging studies on alloying-type anode materials offering significant prospects to meet this challenge. Here, recent advances on alloying-type anodes and their composites for PIBs are reviewed in detail and in a systematic way to capture key aspects from fundamental working principles through major progress and achievements to future perspectives and challenges. Emphasis is placed on critical aspects such as the alloying mechanism and correlation of electrode design and structural engineering for performance enhancement and the crucial role of electrolyte compatibility, additives and binders. The review in appraising all the important contributions on this topic allows for a critical assessment of the research challenges and provides insights on future research directions that can accelerate the important development of PIBs as a viable battery energy storage system.     

锂离子电池负极材料研究进展

锂离子电池(LIB)因其无记忆效应、环境友好且自放电小等各项优异性能得到了相关研究者的重点关注.信息电子产品、电动汽车和智能电网的发展对高能量密度、长循环寿命和低成本的LIB产生了巨大需求.负极作为LIB的重要组成部分之一,其性能对电池整体的各项指标有重要影响,要求负极所应用的材料具有高比容量和优异的循环性能等特性.传...     

Graphene sheets decorated with ZnO nanoparticles as anode materials for lithium ion batteries

ZnO/graphene composites were synthesized using a facile solution-based method. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and Raman spectra revealed that ZnO nanoparticles with a particle size of around 4 nm were densely and homogeneously deposited on graphene sheets. As the anode material for the lithium ion batteries, the ZnO/graphene composites delivered a stable capacity of 404 mAh/g after 100 cycles at a current rate of 0.5 C, which is much superior to bare ZnO nanoparticles. The battery performance result indicates the presence of graphene sheets in the composites effectively enhance the conductivity and accommodate the volume change.     

Carbon nanotubes anchored with SnO2 nanosheets as anode for enhanced Li-ion storage

The carbon nanotubes (CNTs) anchored with SnO₂ nanosheets were prepared using a hydrothermal method. The as-prepared products were characterized by X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analyses, field emission scanning electron microscope and transmission electron microscope. The electrochemical performances of SnO₂ nanosheets/CNTs composite were measured by galvanostatic charge/discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the SnO₂ nanosheets/CNTs composite maintains high lithium storage capacity and good cycling stability. The designed structure plays key role in improving electrochemical performance. The CNTs anchored with SnO₂ nanosheets will be an ideal candidate of anode material for lithium ion batteries.     

生物基材料单体生物-化学组合开发研究现状

生物-化学组合技术对于延长生物基化学品的产品链、开发生物基材料单体是非常重要的技术。本文综述了生物基乙烯和生物基丙烯酸的生物-化学组合开发研究成果,从发酵原材料出发,考虑经过发酵生产平台化合物,平台化合物经过化学催化过程生产聚合物单体,从系统角度考虑各阶段的优化与系统的集成,为生物基材料单体的高效生产提供技术支持。     

Interconnected MoO2 nanocrystals with carbon nanocoating as high-capacity anode materials for lithium-ion batteries

A facile one-pot hydrothermal method has been developed for the preparation of carbon-coated MoO(2) nanocrystals. The annealed MoO(2)-C nanocomposite consists of interconnected MoO(2)@C nanocrystals. When evaluated for lithium storage capabilities, these MoO(2)@C nanocrystals exhibit high specific capacities (~640 mA h g(-1) at 200 mA g(-1) and ~575 mA h g(-1) at 400 mA g(-1)) and excellent cycling stability. In view of the excellent lithium storage properties and the ease in large-scale preparation, the as-synthesized MoO(2)-C nanocomposite might be used as promising anode materials for high-performance lithium-ion batteries.     

Mn元素对AP65阳极组织和性能的影响

采用熔炼铸造法制备AP65合金阳极材料,采用恒电流扫描法、动电位极化扫描法和浸泡法研究Mn含量对其在3.5%NaCl中的电化学性能和自腐蚀性能的影响,采用光学显微镜、扫描电镜和X射线衍射仪对其显微组织和腐蚀形貌进行观察和检测。结果表明Mn元素的加入,能粗化AP65阳极的铸态组织,使AP65阳极的腐蚀电位正移,腐蚀电流密度减小,耐蚀性能得到显著提高;使AP65阳极平均电极电位负移,当Mn含量为0.3%时,AP65阳极平均电极电位最负,达到-1.528VSCE。     

Multiwalled carbon nanotubes anchored with SnS2 nanosheets as high-performance anode materials of lithium-ion batteries

A nanocomposite of multiwalled carbon nanotubes (MWCNTs) anchored with SnS(2) nanosheets (NS) (SnS(2) NS@MWCNTs coaxial nanocables) has been synthesized through a simple solution-based method at room temperature. The synthetic mechanism of these intriguing nanocomposites is proposed as electrostatic attraction between tin ions and MWCNTs, followed by the nucleation and two-dimensional growth of SnS(2). The as-synthesized SnS(2) NS@MWCNTs coaxial nanocables have been applied as anode materials for lithium-ion batteries, which show better lithium storage performance compared to pure SnS(2) nanosheets and MWCNTs. The combination of MWCNTs that can hinder the agglomeration and enhance electronic conductivity of the active materials might be responsible for the enhanced cyclic performance.     

锡锑合金/石墨复合材料作为锂离子电池负极的研究

通过球磨的方法制备了锡锑合金/石墨复合材料,应用XRD、SEM和电化学方法对锡锑合金/石墨复合材料的微观结构和电化学性能做了研究.复合材料的首次可逆容量达到416 mAh/g,锡锑合金/石墨复合材料的循环稳定性相比于锡锑合金有了很明显的改善.对锡锑合金含量与复合材料吸放锂性能的研究表明,含锡锑合金50%的锡锑合金/石墨复合材料循环稳定性最好,到第20个循环时,容量保持率为88%(锡锑合金为81%),是有希望的锂离子电池负极材料.     

Optical properties of polyethylene/styrene-co-methacrylate copolymers IPN-like networks: Effect of different methacrylate styrene co monomers on properties

Low-density Polyethylene (PE) were synthesized with poly[butyl methacrylate (B)-co-styrene (S)], poly(dodecyl methacrylate(D)-co-styrene] and poly(ethyl hexyl methacrylate (EH)-co-styrene] copolymers in order to obtain IPN-like networks. Different S/methacrylate copolymer molar ratios going from 0/100 up to 60/40, a molar percentage of 1.0% of 1,4-butanedioldimethacrylate (b) and 3 wt% of 2,5-dimethyl-2,5-di-(tert-butyl peroxy) hexane (Luperox 101) were used. The samples were analyzed at RT by WAXS, swelling in CCl₄ and mechanical tensile tests. Dynamic-mechanical tests and optical investigations were performed in a temperature range between RT and 180°C. All the IPN types showed optical reversible transitions (transparency-to opacity and vice versa) with varying temperature, due to a refractive index (RI) matching-mismatching of PE and copolymer networks. The copolymer chemical nature as well as its composition affected sensitively most of the analyzed properties.     

Synthesis and polymerization of substituted ammonium sulfonate monomers for advanced materials applications

Sulfonated polymers have found use as ion-exchange membranes for use in fuel cells, water purification, electroactive devices, and inorganic materials templating and synthesis. Improving the materials for these applications and opening up new applications requires the ability to synthesis targeted or more complex sulfonated polymers, which includes tailoring the chemistry (copolymerization across a wider range of solubility) and/or polymer architecture (block, graft, nanoparticle). This article will summarize the recent work using sulfonated monomers with substituted ammonium counterions as a versatile route for enabling this goal. Two main benefits of these monomers are as follows. First, they are useful for preparing amphiphilic copolymers, which is a challenge using traditional acidic or alkali salt forms of sulfonated monomers. Second, sulfonated polymers with substituted ammonium counterions are useful polymers for obtaining unique material properties, such as organo-gelation of low polarity solvents or obtaining ionic liquid polymers for the fabrication of solid polymer electrolytes.     

Permanent magnets based on materials with high crystal anisotropy

The properties of Alnicos and elongated single-domain fine-particle materials, both interpreted as due to shape anisotropy of fine particles, are still far short of those predicted by simple theory. The hard ferrites, with properties due to magnetocrystalline anisotropy, come much closer, but are restricted by their low magnetization. The search for a combination of high magnetization and high magnetocrystalline anisotropy has led to the investigation of a variety of intermetallic compounds. Some of them, particularly the cobalt-rare earths, appear quite promising. Mechanical grinding often has an adverse effect on the magnetic properties of crystal anisotropy materials. Chemical stability is also often a problem. Crystal anisotropy materials in general have high values of intrinsic coercive force. This makes them especially suitable for applications involving widely varying dynamic conditions. Their proper evaluation may be best done using criteria other than the usual maximum energy product.     

Hydrothermal synthesis of SnO nanoflakes as anode materials for lithium-ion batteries

SnO nanoflakes were successfully prepared by a simple hydrothermal process, with the use of hydrazine hydrate as the mineralizer and polyethylene glycol (PEG) or citric acid as an additive. Hydrazine hydrate serves as both a mineralizer and a protective agent against the oxidation of the SnO products at the hydrothermal stage. X-ray diffraction, field-emission scanning electron microscopy (FESEM), and transmission electron microscopy were employed to characterize the products. FESEM images reveal that the thickness of the SnO nanoflakes prepared by the hydrothermal process with the use of PEG as an additive is around 15 nm. The first reversible specific capacity of the SnO nanoflakes reaches 856 mA h/g, which is near the theoretical value (876 mA h/g). Hydrazine hydrate, the hydrothermal temperature, and the surfactant/complexing agent are three key factors for the hydrothermal synthesis of the SnO nanoflakes by the process presented here. The text was submitted by the authors in English.