Charging of Polycarbonate Films in a Direct-Current Discharge

The effect of treatment of Diflon, Makrolon^®, and Lexan^® polycarbonate films in the cathode fall of a dc discharge was studied. Plasma treatment was shown to result in the hydrophilization of the film surface. The dependence of the contact angle on the discharge current and treatment time was examined. It was found that the discharge induced a negative charge on the polycarbonate surface. The surface-charge density was correlated with the contact angle for various treatment conditions. Space charging processes in glow discharge-treated films were investigated using the thermally stimulated relaxation and depolarization techniques. The role of produced charged entities in an increase in the surface energy of modified polycarbonate films was revealed.     

Low-frequency glow discharge treatment of amorphous poly(ethylene terephthalate) films

The influence of treatment in a low-frequency glow discharge on the surface properties of an amorphous poly(ethylene terephthalate) (PET) film was studied. It was shown that, at identical external discharge parameters, changes in the wettability of plasma-treated PET films depended on its morphological structure—the amorphous film had higher values of the contact angle and lower values of the surface charge density than a biaxially oriented poly(ethylene terephthalate) of the PET-E brand.     

Formation of charge states on the surface of a laminated polyimide-fluoropolymer film by glow- discharge treatment

The alteration of properties of both sides of the laminated polyimide-fluoropolymer film PMF-351 by treatment in a low-frequency glow discharge, depending on their position with respect to the electrode, was investigated. By the dynamic capacitance method, it was found that both positive and negative charges can be induced on both sides of the film modified in the cathode fall, depending on the arrangement of its polyimide and fluoropolymer sides with respect to the electrode. It was shown that the formation of a negative charge in PMF-351 is in all cases due to trapping of plasma electrons injected into the polymer surface layers.     

Immobilization of Ciliary Neurotrophic Factor on Model Biomaterials by Plasma Graft Polymerization

Acrylic acid was grafted on the surface of polypropylene (PP) film via plasma‐induced technology. It was shown by FT‐IR that there were carboxyl groups on the surface of the modified PP film. The grafting ratio was analyzed quantitatively through a dyeing process. The effects of the technology parameters of the plasma‐treatment and graft polymerization on the grafting ratio, such as power, discharge time, concentration of monomer and active species density, reaction temperature and time, were characterized. Moreover, the content of ciliary neurotrophic factor (CNTF) that was anchored on the surface of the modified PP film was measured through enzyme‐linked immunosorbent assay (ELISA). The results show that the amount of CNTF immobilized on the surface of the modified PP film increase with increasing content of carboxyl groups, showing that the existence of carboxyl groups on the surface of the PP film is beneficial to the immobilization of CNTF.     

锂离子电池负极碳材料的表面改性与修饰 Ⅲ.人工施加的固体电解质膜对锂碳负极电池性能的改善

研究了人工施加的无机固体电解质晶体膜对锂碳负极电池性能的影响作用,结果表明碳电极的容量及首次充放电效率相对于未改性电极都得到了一定程度的提高,显示了以这层外界人工施加的晶体膜替代由电极体系本身所形成的钝化膜之有效性．扫描电子显微镜的研究直观地显示了这层人工施加膜的均匀、致密性质．     

锂离子电池Sn-SBA15负极材料的复合电镀制备及其性能

应用复合电镀法制备Sn-SBA15电极.充放电测试得其初始放电(嵌锂)容量,达到1075mAh/g.充电(脱锂)容量为630mAh/g,经过50周循环后充放电容量均保持在400 mAh/g以上.XRD分析表明,Sn-SBA15电极具有四方晶型锡结构;而SEM观察到电极表面的蜂窝状结构.交流阻抗谱结果显示,Sn-SBA15电极表面有SEI膜的生成.     

Surface changes brought about by corona discharge treatment of polyethylene film and the effect on subsequent microbial colonisation

Microbial colonisation of synthetic plastic films is normally slow, which affects the total period of biodegradation. Correlation between the modified surface condition and the ability for microorganisms to colonise low-density polyethylene (LDPE) film was studied. Corona discharge treatment was applied to obtain enriched and activated surface condition of LDPE film. It was found from water contact angle and FTIR spectrum evaluations that surface energy was significantly increased due to production of free radicals. Stabilised oxidised LDPE surface was also obtained by further exposure to the corona which gave more suitable condition for subsequent colonisation. Results were compared with UV irradiated (photo-oxidised) LDPE films. Colonisation of corona discharged and UV treated LDPE films were tested in the laboratory environment using known fungal isolates and in a natural compost environment. More active microbial colonisation was observed in all cases for corona discharged and UV treated LDPE films. Far longer UV exposure was required to have the same physicochemical and biological effect as the corona discharge treatment.     

Novel method to enhance the cycling performance of spinel LiMn2O4

In this study, a novel method was presented to improve the cycle performance of the spinel LiMn₂O₄ This method is quite different from the traditional way of coating LiMn₂O₄ particle itself with inorganic and organic compounds. First we covered the current collector with the mixture of LiMn₂O₄ particle, conductive agents and binders, and then deposited an aluminum film onto it by means of vacuum evaporation. The pure electrode and the modified electrode were investigated using a combination of scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and charge–discharge tests. The enhancement of the capacity retention of modified electrode is significant, maintaining 93.5% of the maximum capacity after 200 cycles at charge–discharge rate of C/2, while pure electrode only 63.7%. It was found that the improvement of cycling performance is greatly ascribed to the good electrical conductivity of aluminum film deposited on the surface of spinel LiMn₂O₄.     

Grafting of acrylamide onto cellulosic fibers via dielectric-barrier discharge

Fully bleached kraft pulp (BKP) and thermomechanical pulp (TMP) fibers were grafted with acrylamide via dielectric-barrier discharge treatment at various treatment dosages. The results indicate that increased dielectric-barrier discharge treatment leads to the increased polymerization and incorporation of acrylamide onto fiber surfaces. Greater incorporation of poly(acrylamide) occurs on the BKP fibers than the TMP at the same treatment conditions. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning electron microscopy (SEM) indicate that dielectric-barrier discharge initiated modifications to fiber surface topo-chemistry occur across the fiber such that the sheet is randomly peppered with modified areas; however, it occurs in patches on individual fibers as opposed to occurring as an evenly distributed thin film. SEM and elemental analysis also showed that the incorporation of acrylamide onto the fiber surface increases with increased treatment dosages.     

Study of charge storage in the nanofibrous poly(ethylene terephthalate) electrets prepared by electrospinning or by corona discharge method

In this paper, the charge storage performance of electrospun poly(ethylene terephthalate) (PET) mats with high specific surface area was evaluated in comparison to that of PET film electrets. Corona discharge method was used to charge the electrospun PET mats and PET films. The surface potential decay measurements revealed that the corona charged РЕТ mats had higher initial values for the normalized surface potential compared to the РЕТ electret films. A tendency for stabilization of the electret charge to one and the same value for all charged samples (mats and films) after the 50th day was observed. The peaks at 90 °C in the thermally stimulated current (TSC) spectra of uncharged and charged in corona discharge electrospun PET mats were observed and attributed to a relaxation of the separated space charges, the dipole disorientation or injected charges within the bulk. It was found that the value of the storage charge in a corona charged electrospun PET mats was higher than that in PET mats prepared by electrospinning.     

Polypropylene Films in a Direct-Current Discharge

The effect of dc discharge treatment on polypropylene films—both commercial and stabilizer- and plasticizer-free as prepared under laboratory conditions (with the rac-Et(Ind)₂ZrCl₂–methylaluminoxane catalytic system)—was studied. The discharge treatment was shown to hydrophilize the polypropylene surface in both cases. Negative charged states were detected on the modified surface and their relation to the polypropylene hydrophilization was established. By the thermostimulated relaxation and depolarization techniques, it was shown that the observed charges are induced by injection of plasma electrons into the polymer. It was found that severe changes took place throughout the bulk of the polypropylene film synthesized over the metallocene catalyst, as indicated by enhancement of its crystallinity and a change in the molecular mass distribution.     

Chemical and physical modification and electret properties of polytetrafluoroethylene films

Composites with titanium oxide structures on the surface of a polymer matrix were prepared by preliminary plasma activation of polytetrafluoroethylene films, followed by chemical treatment with vapors of titanium tetrachloride and water. The chemical composition and structure of the modified film surface were studied by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The stability of the formed surface charge increases in going from the initial film to the plasma-activated film, then to the film successively treated with vapors of titanium tetrachloride and water, and finally to the plasma-activated film treated subsequently with vapors of titanium tetrachloride and water. The modified polytetrafluoroethylene films are of interest as electrets with enhanced operation characteristics.     

Wettability interpretation of oxygen plasma modified poly(methyl methacrylate)

Poly(methyl methacrylate) (PMMA) has been modified via a dc pulsed oxygen plasma for different treatment times. The modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), optical profilometer, zeta potential, and advancing contact angle measurements. The measured advancing contact angles of water decreased considerably as a function of discharge. Several oxygen-based functionalities (carbonyl, carboxyl, carbonate, etc.) were detected by XPS, while zeta potential measurements confirmed an increase in negative charge for the treated PMMA surface. Evaluating the correlation between the concentration of polar chemical species and zeta potential, we found that increase in surface hydrophilicity results from the coeffect due to incorporation of oxygen functional groups and creation of charge states. The electrical double layer (EDL) effect was also considered in contact angle interpretation by introducing an additional surface tension term into Young's equation. We also found that EDL contribution to the solid-liquid interfacial tension is negligible and can be safely ignored for the systems considered here.     

锡钴合金电沉积层的结构与锂离子嵌脱行为

应用电沉积方法制备Sn-Co合金镀层.X-射线衍射和扫描电子显微镜分析表明,该Sn-Co合金镀层为六方固溶体结构,含Co量为20%的Sn-Co合金,其沉积层呈现(110)择优取向.表面微孔随沉积层Co含量的增加而增多.以Sn-Co合金镀层作锂离子电极材料,电化学性能测试表明,其首次充电曲线表现出锡钴合金、锡及锡氧化物与锂合金化的多个反应综合特征,随后的充电曲线趋于稳定,呈现L i-Sn-Co合金化反应特征;具有择优取向和多孔结构的Sn-Co合金电极材料的充放电性能较好,首次库仑效率为63.9%,经过20次充放电循环后,其充电容量为461mAg/h,库仑效率为99%.     

锂离子电池负极碳材料的表面改性与修饰Ⅱ.具有“核壳”结构的碳及其对电池性能的影响

以具有气相碳化形式的精制煤焦油沉积碳为壳层材料、人造石墨（ＡＧ）及中间相石墨微球（２８００℃）为核材料制备了核壳结构的碳及碳电极．核壳结构碳及核壳结构碳电极的充放电研究表明碳负极的稳定充放电容量及首次充放电效率都得到了较大的改善,循环伏安研究表明在０．７Ｖ（ｖｓＬｉ＋／Ｌｉ）左右用于形成碳电极表面钝化膜的溶剂的还原分解峰显著减小,显示了核壳结构碳材料电极对电极表面钝化膜的影响作用,Ｘ射线衍射研究揭示了石墨及石墨电极上的无定形碳壳层的存在     

Electrochemical performance of silicon thin film anodes covered by diamond-like carbon with various surface coating morphologies

Four different kinds of diamond-like carbon (DLC) coating morphologies on the surface of silicon films were prepared directly on a copper foil by using radio frequency plasma-enhanced chemical vapor deposition at 200 °C. A thin double layer film consisting of DLC (60 nm) and silicon film (250 nm) was fabricated for use as the anode material of lithium secondary batteries, and its electrochemical performance was also examined with special attention being paid to the surface coverage of the DLC film. The full coverage of silicon by the DLC film resulted in poor capacity due to the ensuing low reactivity with the lithium ions. On the other hand, the partial coating of the DLC film on the silicon film not only reduced the capacity fading, but also increased the discharge capacity during the charge/discharge cycles. These results indicated that the good dispersion of the DLC coating, obtained by using a smaller coating sector on the silicon film, improved the integrity of the electrode structure, thus giving higher capacities and reduced capacity fading.     

CuTSPc分子膜/p-Si(111)界面的光致电荷转移及其机制研究

本文利用L-B技术,在p-Si(111)基底上铺展了单层厚度只有6Å的CuTSPc超薄分子膜(简称超分子膜)和具有C₁₈脂链间隙的CuTSPc L-B膜两种膜系,首次观察到了CuTSPc分子膜在这种特定界面中的表面光电压谱。并且发现,当CuTSPc仅为一个单分子层时,这两种膜系的表面光伏效应最强。我们的研究结果表明,只有紧邻半导体基底的一个单分子层厚度的染料分子对光致界面电荷转移起关键作用。最后在实验上证实这种电荷转移是电荷直接注入机制,而非间接注入机制。     

锂离子电池负极碳材料的表面改性与修饰Ⅰ．表面的氧化、还原处理对碳材料电极性能的影响

通过各种氧化／还原体系对碳材料进行表面氧化、还原处理,研究了碳材料表面的痕量有机含氧官能团对以碳材料作为锂离子电池负极的电池性能的影响．结果表明,碳材料表面大量有机含氧官能团的存在将引起电池性能的严重恶化;相应地如对电极表面进行一定的还原处理、以减少碳表面有机官能团的含量及其氧化程度则可提高电极（碳材料）的容量及首次循环效率．文中还结合碳材料表面有机官能团对电解液溶剂的分解反应以及碳电极表面钝化膜形成的影响进行了解释．     

脉冲激光沉积LiFePO4阴极薄膜材料及其电化学性能

采用脉冲激光沉积结合高温退火的方法在不锈钢基片上制备了LiFePO₄薄膜电极. XRD谱图显示, 经650 ℃退火制得的是具有橄榄石结构的LiFePO₄薄膜. 充放电测试表明, LiFePO₄薄膜具有3.45/3.40 V的充放电平台, 与LiFePO₄粉体材料相当. 首次放电容量约为27 mAh•g^－1, 充放电循环100次后容量衰减51%.     

高电压镍锰酸锂正极/电解液界面本征性质的研究

高电压正极材料的应用是提高锂离子电池能量密度的有效手段,然而高电压下正极/电解液界面稳定性成为决定锂离子电池在高电压工作条件下循环性能和安全性能的关键因素,因此高电压下正极/电解液界面具有重要的研究价值. 但是,目前报道的正极/电解液界面的研究中通常使用传统的极片制备方法,这需要引入导电剂和粘结剂,会对后期正极活性物质表面钝化膜的形貌和组分表征带来干扰,甚至造成固体电解质界面(SEI)膜存在的假象,难以获得正极材料与电解液之间界面的本征信息. 这里,我们采用溶胶凝胶旋涂法制备了不含导电剂和粘结剂的镍锰酸锂(LNMO)正极,以其为研究对象,通过扫描电镜(SEM)、原子力显微镜(AFM)和X射线光电子能谱(XPS)技术,结合电化学阻抗谱(EIS)研究了LNMO正极/电解液界面在充放电过程中的结构演变过程以及本征性质. 研究结果显示在充放电过程中,电解液中溶剂和电解质都会参与反应,其中LiPF₆的降解主要发生在高电压下,其降解产物在放电过程中又会被反应消耗掉. 它们的降解产物沉积到LNMO正极形成表面膜,该表面膜的主要成分随着电压的不同组分有所不同.