石墨烯包覆碳纳米管-硫(CNT-S)复合材料及锂硫电池性能

针对锂硫电池研究与实际应用中遇到的主要问题, 本文通过一种简单有效的水热法还原氧化石墨烯对商用碳纳米管-硫(CNT-S)纳米复合材料进行包覆, 形成一种可有效抑制多硫聚合物扩散的石墨烯包覆结构。X射线衍射(XRD), 扫描电子显微镜(SEM)表征结果表明硫均匀地负载在碳纳米管上, 并且在CNT-S复合材料外表面包覆有一层石墨烯。电化学测试结果表明, 这种包覆结构能显著提高CNT-S复合材料的锂硫电池性能。     

石墨烯包覆碳纳米管-硫(CNT-S)复合材料及锂硫电池性能

针对锂硫电池研究与实际应用中遇到的主要问题,本文通过一种简单有效的水热法还原氧化石墨烯对商用碳纳米管-硫(CNT-S)纳米复合材料进行包覆,形成一种可有效抑制多硫聚合物扩散的石墨烯包覆结构。X射线衍射(XRD),扫描电子显微镜(SEM)表征结果表明硫均匀地负载在碳纳米管上,并且在CNT-S复合材料外表面包覆有一层石墨烯。电化学测试结果表明,这种包覆结构能显著提高CNT-S复合材料的锂硫电池性能。     

硫/水热碳球复合材料的制备及对锂硫电池倍率性能的影响

在锂硫电池正极材料的研究中,碳材料可以有效改善电池倍率及循环性能.为了提高锂硫电池的高倍率放电性能,通过水热合成的方法,制备了由非均匀粒径碳球组成的碳材料.与硫热合成后,硫均匀分布在碳材料表面及周围,复合材料含硫量为52wt%.0.2C放电电流下,首次放电比容量为1174mAh·g^-1,100次循环后放电比容量为788mAh·g^-1.在4C的放电电流下,放电比容量稳定维持在600mAh·g^-1,循环过程中,库伦效率高于90%.该碳材料有良好的导电网络,且制备方便,成本低廉,对于穿梭效应和放电过程中的膨胀效应有一定的抑制作用,是一种优秀的正极材料.     

硫/水热碳球复合材料的制备及对锂硫电池倍率性能的影响(英文)

在锂硫电池正极材料的研究中,碳材料可以有效改善电池倍率及循环性能。为了提高锂硫电池的高倍率放电性能,通过水热合成的方法,制备了由非均匀粒径碳球组成的碳材料。与硫热合成后,硫均匀分布在碳材料表面及周围,复合材料含硫量为52wt%。0.2C放电电流下,首次放电比容量为1 174 m Ah·g-1,100次循环后放电比容量为788 m Ah·g-1。在4C的放电电流下,放电比容量稳定维持在600 m Ah·g-1,循环过程中,库伦效率高于90%。该碳材料有良好的导电网络,且制备方便,成本低廉,对于穿梭效应和放电过程中的膨胀效应有一定的抑制作用,是一种优秀的正极材料。     

锂硫电池正极用硫/介孔碳复合材料的制备及电化学性能

制备了以十二烷基硫酸钠(SDS)为模板的介孔碳,并将介孔碳和单质硫采用熔融渗透法复合制得硫/介孔碳复合材料。SEM、TEM和BET结果显示介孔碳成直径约为500 nm的大小均一的球体,存在孔径为2 nm的微孔;单质硫充分填充在介孔碳的微孔中。以硫/介孔碳复合物作为锂硫电池正极材料时显示出高的电化学性能。初始放电容量高达1519 mAh·g^-1,在200 mA·g^-1的电流密度下充放电200个循环后依然能保持在835 mAh·g^-1。硫/介孔碳复合材料的高倍率性能和优异的循环稳定性,源于介孔碳良好的导电性及其孔结构的固硫作用。     

锂硫二次电池硫-碳纳米管正极的合成和性能

由单质硫与碳纳米管合成一种新型含碳复合材料.XRD、SEM、BET比表面和孔径分布表征观察硫-碳纳米管复合材料,循环伏安法和电池充放电测试材料的电化学性能.结果表明:以硫-碳纳米管作正极组装的2016型扣式电池有较好的电化学性能,其初始放电比容量达680mAh/g(室温),30次循环放电比容量仍稳定在500mAh/g.     

硫/多孔碳纳米管复合材料的制备及电化学性能

为了解决单质硫导电性差、充放电过程中体积膨胀、中间产物多硫化物的穿梭效应等问题,将硫负载于一种高比表面积的多孔碳纳米管（PCNTs）,制备了S/PCNT复合材料,研究了其电化学性能。相比于S/CNT,S/PCNT的电化学性能有明显提升,这可归因于S/PCNT中的嵌入结构,为硫在充放电过程中的体积膨胀提供了缓冲空间,避免了硫与电解液的直接接触,进而有效限制多硫化物的溶解,从而缓解多硫化物的穿梭效应,使硫正极具有更好的循环稳定性。     

多壁碳纳米管-氮化钒空心球复合材料作为高效硫载体用于锂硫电池

以多壁碳纳米管/氮化钒复合材料(MWCNT-VN)作为锂硫电池正极载体材料,利用VN的空心结构储存硫和限制多硫化物的穿梭效应.另外,MWCNT形成了一个导电网络,进一步提升了正极的导电性能.在1C的电流密度下,VN/S电极与MWCNT-VN/S电极的初始放电比容量分别为702.2和809.3 mAh·g-1,经过350...     

碳膜夹层锂硫电池的电化学性能

选取Super-P（SP）、KB或MWCNTs导电碳膜夹层,并置于硫电极与隔膜间组装成扣式锂硫电池.相关评估结果表明,碳膜夹层可显著提高锂硫电池循环性能,硫电极（载硫量为80%,by mass,下同）循环40周后比容量均在800 mAh·g^-1以上. 上述三种碳膜的物理性质有较大差异,导致相应电池具有不同电性能. KB碳膜夹层电池呈现较强的电化学极化效应;SP碳膜夹层电池循环初期可释放出最高的比容量,而循环稳定性较差;MWCNTs碳膜可视为较适宜的导电碳夹层材料.     

锂硫电池膨胀氧化石墨/硫复合正极材料的制备及其性能

以棒状石墨为原料,采用改良的Hummers法与热处理制备得到膨胀氧化石墨(E-GO),利用在酸性水溶液中归中化学反应的方法合成纳米尺寸的硫颗粒,使其嵌入到膨胀氧化石墨的内部,制备了膨胀氧化石墨-硫复合材料。采用红外光谱,X-射线光电子能谱表征了膨胀氧化石墨表面官能团的存在和种类;X-射线衍射分析结果表明生成的硫属于斜方晶结构;扫描电子显微镜和透射电镜分析证明了材料中硫的均匀分布。恒电流充放电结果表明该复合正极材料的首次放电容量为1 020 mAh.g-1,100周循环之后其容量还保持在650 mAh.g-1左右;材料的倍率性能和库伦效率优异,这可能得益于小尺寸的硫在材料中均匀分布,以及表面官能团对硫的固定化作用。     

Core-shell meso/microporous carbon host for sulfur loading toward applications in lithium-sulfur batteries

Lithium-sulfur(Li-S) batteries belong to one of the promising technologies for high-energy-density rechargeable batteries.However,sulfur cathodes suffer from inherent problems of its poor electronic conductivity and the shuttling of highly dissoluble lithium polysulfides generated during the cycles.Loading sulfur into porous carbons has been proved to be an effective approach to alleviate these issues.Mesoporous and microporous carbons have been widely used for sulfur accommodation,but mesoporous carbons have poor sulfur confinement,whereas microporous carbons are impeded by low sulfur loading rates.Here,a core-shell carbon,combining both the merits of mesoporous carbon with large pore volume and microporous carbon with effective sulfur confinement,was prepared by coating the mesoporous CMK-3 with a microporous carbon(MPC) shell and served as the carbon host(CMK-3 @MPC) to accommodate sulfur.After sulfur infusion,the as-obtained S/(CMK-3@MPC) cathode delivered a high initial capacity of up to 1422 mAh·g~(-1) and sustained 654 mAh·g~(-1) reversible specific capacity after 36 cycles at 0.1 C.The good performance is ascribed to the unique core-shell structure of the CMK-3@MPC matrix,in which sulfur can be effectively confined within the meso/microporous carbon host,thus achieving simultaneously high electrochemical utilization.     

Facile synthesis and performance of polypyrrole-coated sulfur nanocomposite as cathode materials for lithium/sulfur batteries

In situ chemical oxidation polymerization of pyrrole on the surface of sulfur particles was carried out to synthesize a sulfur/polypyrrole （SIPPy） nanocomposite with core-shell structure. The composite was characterized by elemental analysis, X-ray diffraction, scanning/transmission electron microscopy, and electrochemical measurements. XRD and FTIR results showed that sulfur well dispersed in the core-shell structure and PPy structure was successfully obtained via in situ oxidative polymerization of pyrrole on the surface of sulfur particles. TEM observation revealed that PPy was formed and fixed to the surface of sulfur nanoparticle after polymerization, developing a well-defined core-shell structure and the thickness of PPy coating layer was in the range of 20-30 nm. In the composite, PPy worked as a conducting matrix as well as a coating agent, which confined the active materials within the electrode. Consequently, the as prepared SIPPy composite cathode exhibited good cycling and rate performances for rechargeable lithium/sulfur batteries. The resulting cell containing SIPPy composite cathode yields a discharge capacity of 1039 mAh·g^-1 at the initial cycle and retains 59% of this value over 50 cycles at 0.1 C rate. At 1 C rate, the SIPPy composite showed good cycle stability, and the discharge capacity was 475 mAh·g^-1 after 50 cycles.     

Well-dispersed sulfur anchored on interconnected polypyrrole nanofiber network as high performance cathode for lithium-sulfur batteries

Preparation of novel sulfur/polypyrrole (S/PPy) composite consisting well-dispersed sulfur particles anchored on interconnected PPy nanowire network was demonstrated. In such hybrid structure, the as-prepared PPy clearly displays a three-dimensionally cross-linked and hierarchical porous structure, which was utilized in the composite cathode as a conductive network trapping soluble polysulfide intermediates and enhancing the overall electrochemical performance of the system. Benefiting from this unique structure, the S/PPy composite demonstrated excellent cycling stability, resulting in a discharge capacity of 931 mAh g⁻¹ at the second cycle and retained about 54% of this value over 100 cycles at 0.1 C. Furthermore, the S/PPy composite cathode exhibits a good rate capability with a discharge capacity of 584 mAh g⁻¹ at 1  C.     

Hierarchically porous nitrogen-doped carbon foams decorated with zinc nanodots as high-performance sulfur hosts for lithium-sulfur battery

To prevent polysulfides from dissolution into electrolyte, we propose a novel and simple approach to nitrogen-doped carbon foams which contain hierarchically porous structure and are decorated with zinc nanodots through one-pot carbonization and activation process. These carbon foams, which serve as hosts for sulfur in lithium battery, can provide a conducting network and shorter diffusion length for Li-ions. Specially, the zinc nanodots derived from the carbothermal reaction of ZnCl₂ at high temperature can interact with sulfur/polysulfides by strong chemisorption. In addition, the zinc nanodots can also facilitate the conversion reaction between Li₂S_x (2 < x < 8) and Li₂S/Li₂S₂. Therefore, Zn@NCFs/S cathode presents high sulfur utility and large capacity.     

Sulfur/carbon composites prepared with ordered porous carbon for Li-S battery cathode

Ordered porous cabon with a 2-D hexagonal structure,high specific surface area and large pore volume was synthesized through a twostep heating method using tri-block copolymer as template and phenolic resin as carbon precursor.The results indicated the electrochemical performance of the sulfur/carbon composites prepared with the ordered porous carbon was significantly affected by the pore structure of the carbon.Both the specific capacity and cycling stability of the sulfur/carbon composites were improved using the bimodal micro/meso-porous carbon frameworks with high surface area.Its initial discharge capacity can be as high as 1200 mAh·g~(-1) at a current density of 167.5 mA·g~(-1)The improved capacity retention was obtained during the cell cycling as well.     

锂离子电池用复合导电剂浆料制备与性能

采用超声波混合、抽滤的方法把多壁碳纳米管（MWCNTs）和乙炔黑混合制备了锂离子电池用复合导电剂浆料，用扫描电子显微镜（SEM）和恒流充放电测试考察了复合导电剂的结构和其作为导电剂对LiCoO2电极放电比容量的影响。SEM的分析结果表明MWCNTs和乙炔黑实现了纳米层次的均匀混合。复合导电剂悬浮液和浆料分别被用作导电剂制成了两种LiCoO2电极，前一种电极为Cathode A，后一种电极为Cathode B，考察了不同MWCNTs含量时，两种电极0．5C第10次放电比容量的差异。实验结果表明，随着MWCNTs含量的增加，两种电极放电比容量的差值增大，说明低含量MWCNTs的复合导电剂浆料是一种理想的锂离子电池导电剂。