锂离子电池SnSb/C复合负极材料的热碳还原法制备及电化学性能研究

采用高温还原技术,以SnO2,SbO3为原料,分别以葡萄糖、中间相碳微球(MCMB)作为还原剂,制备了两种结构的SnSb/C复合材料,并对比了它们的形貌和电化学性能.采用X射线衍射技术、拉曼技术、扫描电子显微镜技术对材料的结构和形貌进行了表征,并且通过测试恒电流充放电曲线、循环伏安曲线和交流阻抗谱分析了材料的电化学性能.实验结果表明:葡萄糖作为还原剂时,形成以合金颗粒为内核,絮状碳壳均匀包裹的微米球状结构,首次放电比容量为793.379 mA·h·g-1,循环50周后仍维持在449.987 mA·h·g-1;而以MCMB作为还原剂时,形成合金颗粒与MCMB混合共存并部分包覆的结构,首次放电比容量为1164.938 mA·h·g-1,50周后的比容量仅有290.807 mA·h·g-1.     

锂离子电池Sn-Al薄膜电极的制备及电化学性能研究

采用磁控溅射沉积技术制备了纳米级Sn-Al合金薄膜电极材料,并用X射线衍射和扫描电子显微镜进行表征,用高精度电池测试系统进行充放电和循环伏安测试.结果表明直流DC与射频RF两种不同的溅射方法制备的Sn-Al薄膜电极具有很大的性能差异,前者DC法制备的材料颗粒细小,表现出稳定的循环性能,其首次放电容量为1060 mAh/g,首次效率为71.7％,电极经过50次循环后比容量保持在700 mAh/g以上.后者RF法制备的材料颗粒较大,放电比容量开始上升,第五次循环后接着逐渐衰减,表现出较差的循环性能. 关键词： 锂离子电池 磁控溅射 Sn-Al合金 电化学性能     

碳热还原法制备V2O3-C双层包覆磷酸铁锂及其电化学性能

通过V₂O₅的碳热还原反应制备了具有优异倍率性能和循环稳定性的V₂O₃-C双层包覆的磷酸铁锂正极材料. 粉末X射线衍射、元素分析、高分辨投射电镜和拉曼光谱研究表明V2O3相与碳层共包覆于磷酸铁锂颗粒表面. 在V₂O₅的碳热还原反应后,碳含量明显降低,但石墨化程度未发生明显改变. 电化学测试结果表明少量V₂O₃显著改善了磷酸铁锂正极材料的倍率性能和高温循环性能,包含1%氧化钒的复合正极材料在0.2 C放电容量为167 mAh/g,5 C时放电容量为129 mAh/g,并且循环稳定性优异;在55 oC和1 C时放电容量为151 mAh/g,循环100次后无明显容量衰减.     

纳米铜掺杂Li(Ni_(0.6)Co_(0.2)Mn_(0.2))O_2正极材料的制备和性能研究

通过Cu纳米颗粒掺杂制备了Li[(Ni_(0.6)Co_(0.2)Mn_(0.2))_(1-x)Cu_x]O_2三元正极材料,并通过调节Cu的掺杂量,讨论了Cu的掺入对Li[(Ni_(0.6)Co_(0.2)Mn_(0.2))_(1-x)Cu_x]O_2三元正极材料晶体结构、表面形貌、电化学性能和循环性能等一系列性能的影响,铜掺杂量为x=0.01时,在0.2C倍率下的首次放电比容量达到了219.1 mAh/g,经过50次充放电循环之后,剩余比容量为115.4 mAh/g。最终结果为Li[(Ni_(0.6)Co_(0.2)Mn_(0.2))_(1-x)Cu_x]O_2中Cu的掺入量为x=0.01时,所得正极材料的电化学性能和循环性能最为优异。     

锂离子电池Sn-Ti合金负极材料的制备及性能研究

采用磁控溅射沉积技术制备了纳米级Sn-Ti合金负极材料,并用X射线衍射和扫描电子显微镜进行表征,用高精度电池测试系统进行充放电和循环伏安测试.结果表明先镀Sn后镀Ti（Sn/Ti复合膜）和先镀Ti后镀Sn（Ti/Sn复合膜）具有很大的性能差异,其中Sn/Ti复合膜具有优异的循环稳定性和较高的可逆容量.首次放电容量和充电容量分别为9275 mAh/g和6954 mAh/g,首次库仑效率为75％,经30次循环后,该电极的放电容量保持为4152 mAh/g,这主要归因于活性物质Sn与电解液界面之间存在非活 关键词： 锂离子电池 磁控溅射 Sn-Ti合金 电化学性能     

Co_2SnO_4/Graphene复合材料的制备与电化学性能研究

实验首先采用改进的Hummers法制备氧化石墨,然后以氧化石墨烯为前驱体,通过水热法将锡酸钴纳米颗粒均匀镶嵌在石墨烯薄膜基片上,最终获得Co2SnO4/Graphene镶嵌复合材料.采用X射线衍射(XRD)、扫描电子显微镜(SEM)对材料的结构和形貌进行表征,通过恒电流充放电(CC)、循环伏安法(CV)与交流阻抗法(EIS)测试了材料的电化学性能.实验结果表明,石墨烯良好的分散性及较高的电子导电率,可以提高锡酸钴材料的电化学性能,材料首次可逆容量达到1415.2 mA·h/g,50次循环后仍能保持469.7 mA·h/g的放电比容量.     

Mn_3O_4包覆对LiNi_(0.5)Mn_(1.5)O_4正极材料界面电化学性能的提高（英文）

本文采用化学湿磨法,首次将金属氧化物Mn_3O_4包覆于LiNi_(0.5)Mn_(1.5)O_4颗粒表面,使得电极材料的电子电导率从1.53×10~(-7) S/cm提高到3.15×10~(-5) S/cm.电化学测试结果表明Mn_3O_4包覆大大提高LiNi_(0.5)Mn_(1.5)O_4正极材料的倍率性能和高温循环稳定性.最佳包覆样品为2.6wt% Mn_3O_4包覆的LiNi_(0.5)Mn_(1.5)O_4,在10 C倍率下具有108 mAh/g的高放电容并且在55℃下100次循环后仍有78%的容量保持率,远大于未包覆样品67%的容量保持率.     

锂离子电池LiMn1-xFexPO4(0<x<1)正极材料的制备及性能研究

本文采用固相法制备了纯相LiMn_1-xFe_xPO₄/C (x=0.2,0.4,0.6)正极材料,并用X射线衍射(XRD)和扫描电镜(SEM)进行表征,用高精度电池测试系统进行充放电和循环伏安测试.结果表明不同Mn和Fe原子比的电极材料具有很大的性能差异,其中当x=0.4时,材料具有优异的循环稳定性和较高的可逆容量.首次充电容量和放电容量分别达到141.5 mAh/g和125.7 mAh 关键词： 锂离子电池 固相法 1-xFe_xPO₄')" href="#">LiMn_1-xFe_xPO₄ 正极材料     

花状磷酸铁锂的聚乙二醇辅助水热合成及其电化学性能

通过聚乙二醇辅助水热法制备了厚度为200 nm的片状磷酸铁锂晶体,并由此自组装为花状磷酸铁锂颗粒．聚乙二醇在水热体系中作为共溶剂使用,它能有效地降低磷酸铁锂片的厚度,并且作为软模板,使磷酸铁锂片自组装成花状结构．这样的花状磷酸铁锂虽然没经过碳包覆改性,在锂离子电池中仍具有高达140 mAh/g的放电容量,并且表现出优异的循环性能,在循环50次后,容量未出现衰减．这种未经碳包覆的磷酸铁锂材料表现出良好的电化学性能．     

多孔碳纳米球的制备及其电化学性能

以三嵌段共聚物F108为软模板,通过水热法合成酚醛树脂球并在氮气氛围下碳化、KOH活化处理,最终得到多孔碳纳米球材料.通过扫描电子显微镜、透射电子显微镜和氮气吸附分析仪对样品进行表征,结果表明样品的平均粒径为120 nm,球形度高,比表面积达到1403 m~2/g,孔径分布广.通过X射线衍射研究样品的结晶度,傅里叶红外光谱分析样品表面官能团的情况,结果表明KOH处理和高温处理使得样品的微晶结构有序度提高,表面官能团含量降低.以多孔碳纳米球作为超级电容器电极的活性物质,电化学特性测试结果表明,多孔碳纳米球材料的比电容能够达到132 F/g(0.2 A/g),在10 A/g的电流密度下,经过10000次循环充放电后,电容量保留率为97.5%.本文采用水热法制备的多孔碳纳米球电化学性能良好,适用于超级电容器电极材料,研究结果表明,比表面积大、孔径分布合适(具有一定介孔含量)、结晶度高和含有少量表面官能团的理化特性的电极材料,其电化学性能更加优越.     

Pickering emulsion polymerization of polyaniline/LiCoO2 nanoparticles used as cathode materials for lithium batteries

The oil in water (o/w) emulsions were prepared using aniline dissolved in toluene and LiCoO₂ particles as stabilizers (Pickering emulsions). Pickering emulsions are stabilized by adsorbed solid particles instead of emulsifier molecules. The mean droplet diameter of emulsions was controlled by the mass ratio M (oil)/M (solid particles). The emulsions showed great stability during 3 days. The composite materials containing LiCoO₂ and the conductive polymer polyaniline (PANI) have been prepared by means of polymerization of aniline emulsion stabilized by LiCoO₂ particles. The composite materials were characterized by nanosphere and nanofiber-like structures. The nanofiber-like morphology of the powdered material was distinctly different of the morphologies of the parent materials. The electrochemical reactivity of PANI/LiCoO₂ composites as positive electrode in a lithium battery was examined during lithium ion deinsertion and insertion by galvanostatic charge–discharge testing; PANI/LiCoO₂ (1:4) composite materials exhibited the best electrochemical performance by increasing the reaction reversibility and capacity compared to that of the pristine LiCoO₂ cathode. The first discharge capacity of PANI/LiCoO₂ (1:4) was 167 mAh/g, while that of LiCoO₂ was136 mAh/g.     

Tin based alloys for lithium ion batteries

The electrochemical behaviour of a standard electrodeposited equiatomic nickel-tin alloy has been tested. Such a material can be an interesting candidate to make thin film anodes for lithium ion batteries since it is deposited by a simple electroplating technique. Using standard deposition conditions, 3 μm thick films of NiSn alloy were deposited onto copper current collectors. The électrochemical behavior of the electrodes suggests that the decomposition of the NiSn alloy occurs during the lithium insertion leading to the formation of nickel particles, followed by the formation of Li-Sn alloys. It is believed that the extraction of lithium during the discharge leads to the decomposition of the Li-Sn alloys. However, according to the structural characterizations performed on the samples, there is no clear evidence to support these reactions. Despite an interesting theoretical capacity of 682 mAh/g, the maximum capacity observed in the NiSn thin films was 77 mAh/g. This low value of the capacity is related to a very slow diffusion of lithium throughout the electrode. Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999.     

Phosphazene groups modified sulfur composites as active cathode materials for rechargeable lithium/sulfur batteries

A novel phosphazene groups modified sulfur composites cathode [triphosphazene sulfide composite (PS) or nitroaniline–triphosphazene disulfide composite (NPS)] which can give good affinity with electrolytes was prepared. Their chemical structures were identified by FTIR and XRD analysis. SEM analysis showed PS and NPS had a denser and rougher surface structure than elemental sulfur, with many tiny pores on the surface. Contact angles measurement showed that PS had a hydrophilic surface, which exhibited better affinity of ether solvent. When used as a cathode material in lithium–sulfur batteries, its initial discharge capacity was 1,109 mAh/g for NPS, 784 mAh/g for PS. Discharge capacity of NPS was higher than charge capacity, which implied nitroanilino base on sulfur particles involving in generation of polysulfides.     

Improvement of lithium battery performance through composite electrode microstructure optimization

The lithium trivanadate Li_1.2V₃O₈ has been investigated during the past decade as a very promising positive electrode material for lithium batteries due to its high theoretical capacity of 360 mAh/g. However, the experimental capacity remains generally much lower than (about half) the theoretical value. To increase electrode cycling performance in batteries, most researchers generally focus their work on the active material optimisation. Here we show that the polymeric binder of the composite electrode may have an important role on the electrode performance. We describe a new tailored polymeric binder combination with controlled polymer-filler (carbon black) interactions that allows the preparation of new and more efficient electrode architecture. Using this polymeric binder, composite electrodes based on Li_1.2V₃O₈ display a room-temperature cycling capacity of 280 mAh/g (C/5 rate, 3.3-2V) instead of 180 mAh/g using a Bellcore-type composite electrode (PLIon^TM technology). We have coupled SEM observations, galvanostatic cycling and electrochemical impedance spectroscopy in order to define and understand the impact of the microstructure of the composite electrode on its electrochemical performance. Derived from these studies, the main key factors that provide efficient charge carrier collection within the composite electrode complex medium will be discussed. Present findings open up new and attractive prospects for electrode performance optimisation. Paper presented at the Patras Conference on Solid State Ionics — Transport Properties, Patras, Greece, Sept. 14–18, 2004.     

Probing the improved stability for high nickel cathode via dual-element modification in lithium-ion

One of the major hurdles of nickel-rich cathode materials for lithium-ion batteries is the low cycling stability, especially at high temperature and high voltage, originating from severe structural degradation, which makes this class of cathode less practical. Herein, we compared the effect of single and dual ions on electrochemical performance of high nickel (LiNi_0.88Mn_0.03Co_0.09O₂, NMC) cathode material in different temperatures and voltage ranges. The addition of a few amounts of tantalum (0.2 wt%) and boron (0.05 wt%) lead to improved electrochemical performance. The co-modified LiNi_0.88Mn_0.03Co_0.09O₂ displays an initial discharge capacity of 234.9 mAh/g at 0.1 C and retained 208 mAh/g at 1 C after 100 cycles at 45 ℃, which corresponds to a capacity retention of 88.5%, compared to the initial discharge capacity of 234.1 mAh/g and retained capacity of 200.5 mAh/g (85.6%). The enhanced capacity retention is attributed to the synergetic effect of foreign elements by acting as a surface structural stabilizer without sacrificing specific capacity.     

Synthesis and electrochemical properties of Ni doped titanate nanotubes for lithium ion storage

Ni doped titanate nanotubes were synthesized by hydrothermal method using Ni doped rutile TiO₂ nanopowders as a starting material. The electrochemical properties were investigated by cyclic voltammmetric methods. The microstructure and morphology of the synthesized powders were characterized by XRD (X-ray diffraction), and HRTEM (high resolution transmission electron microscopy). Ni doped nanotubes were composed of H₂Ti₂O₅·H₂O with outer and inner diameter of ∼10 nm and 6 nm and showed a initial discharge capacity of 305 mAh/g with poor cycling performance. However, after firing, the Ni doped nanotubes revealed better cycling performance due to lower reaction with hydrate and smaller diameter of the tubes.     

Facile synthesis of N-doped carbon-coated Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> anode for application in high-rate lithium ion batteries

A facile sol-gel approach for the synthesis of lithium titanate composite decorated with N-doped carbon material (LTO/NC) is proposed. Urea is used as a nitrogen source in the proposed approach. The LTO/NC exhibits superior electrochemical performances as an electrode material for lithium-ion batteries, delivering a discharge capacity of as high as 103 mAh g^?1 at a high rate of 20 C and retaining a stable reversible capacity of 90 mAh g^?1 after 1000 cycles, corresponding to 100% capacity retention. These excellent electrochemical performances are proved by the nanoscale structure and N-doped carbon coating. NC layers were uniformly dispersed on the surface of LTO, thus preventing agglomeration, favoring the rapid migration of the inserted Li ion, and increasing the Li⁺ diffusion coefficient and electronic conductivity. LTO with the appropriate amount of NC coating is a promising anode material with applications in the development of high-powered and durable lithium-ion batteries.     

Sn/carbon nanotube composite anode with improved cycle performance for lithium-ion battery

Anode material for lithium-ion battery based on Sn/carbon nanotube (CNT) composite is synthesized via a chemical reduction method. The Sn/CNT composite is characterized by thermogravimetry, X-ray diffraction, and transition electron microscopy. The Sn/CNT composite delivers high initial reversible capacity of 630.5 mAh g^?1 and exhibits stable cycling performance with a reversible capacity of 413 mAh g^?1 at the 100th cycle. The enhanced electrochemical performance of the Sn/CNT composite could be mainly attributed to the well dispersion of Sn nanoparticles on CNT and partially filling Sn nanoparticles inside the CNT. It is proposed that the chemical treatment of CNT with concentrated nitric acid, which cuts carbon nanotube into short pieces and increases the amount of oxygen-functional groups on the surface, plays an important role in the anchoring of Sn nanoparticles on carbon nanotube and inhibiting the agglomeration of Sn nanoparticles during the charge–discharge process.