Electrodeposition and characterization of assembly of Sn on Cu nanorods for Li-ion microbattery application

Assembly of Sn on Cu Nanorods as anode for Li-ion microbatteries was prepared by a two-step electrodeposition design. Firstly, Cu nanorods arrays were grown on copper substrate by anodic aluminum oxide template-assisted growth method. Then, Sn was deposited onto Cu nanorods arrays by galvanostatic deposition. X-ray diffraction and scanning electron microscopy measurements reveal that Cu nanorod arrays are covered with Sn. Electrochemical performances of prepared electrodes were evaluated by charge/discharge cycle measurement. The assembly of Sn on Cu nanorods electrode exhibited highly reversible specific capacity and superior capacity retention resulting from the three-dimensionally nano-architectured design, which exhibits a large surface area, shortened Li-ion diffusion distance, Cu?CSn alloying, and can accommodate the volume expansion of Sn during cycling. Deposition time is an important parameter for fabricating the assembly of Sn on Cu nanorods electrode with suitable structure and morphology.     

Fabrication and electrochemical properties of the Sn–Ni–P alloy rods array electrode for lithium-ion batteries

A new ternary Sn–Ni–P alloy rods array electrode for lithium-ion batteries is synthesized by electrodeposition with a Cu nanorods array structured foil as current collector. The Cu nanorods array foil is fabricated by heat treatment and electrochemical reduction of Cu(OH)₂ nanorods film, which is grown directly on Cu substrate through an oxidation method. The Sn–Ni–P alloy rods array electrode is mainly composed of pure Sn, Ni₃Sn₄ and Ni–P phases. The electrochemical experimental results illustrate that the Sn–Ni–P alloy rods array electrode has high reversible capacity and excellent coulombic efficiency, with an initial discharge capacity and charge capacity of 785.0 mAh g^?1 and 567.8 mAh g^?1, respectively. After the 100th discharge–charge cycling, capacity retention is 94.2% with a value of 534.8 mAh g^?1. The electrode also performs with an excellent rate capacity.     

锂离子电池的合金电极材料的失效研究

采用电镀技术在铜箔上电镀金属锡, 并对其充放电过程中的厚度和结构的变化进行了观察和分析. 锡电极经过热处理后, 活性物质锡与基体铜相互扩散生成中间合金Cu6Sn5. 在合金电极嵌锂过程中, 由于有机电解液的分解, 形成了大量的锂氧化物, 这是合金电极体积膨胀的最主要的原因之一. 锂脱嵌后, 部分锂以Li2SnCu的形态保留在合金中, 造成了合金电极首次充放电的不可逆容量损失. 一些新型电解质的应用可能有助于降低合金电极材料体积的膨胀并提高其循环寿命.     

锂离子电池用α-Fe2O3-Ag复合纳米棒负极材料的制备及储锂性能

采用FeOOH纳米棒为前驱体,通过层层自组装法及随后的热处理过程制备出α-Fe2O3-Ag复合纳米棒.采用透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)和电化学性能测试对样品的形貌、结构及电化学性能进行了表征.结果表明,Ag纳米颗粒均匀地分布在α-Fe2O3纳米棒的表面.作为锂离子电池负极材料,α-Fe2O3-Ag复合纳米棒表现出了较好的循环性能和较高的比容量.180个循环后,其比容量高达549.8 mA.h/g.     

锂离子电池三维多孔Cu6Sn5合金负极材料的制备及其性能

以三维多孔泡沫铜为基底, 通过直接电沉积的方法制备锂离子电池Cu6Sn5合金负极材料. 发现合金表面大量的微孔和“小岛”不仅增大电极的表面积, 而且显著缓解充放电过程中的体积变化. 测得三维多孔Cu6Sn5合金的初始放电(嵌锂)容量为620 mAh·g-1, 充电(脱锂)容量为560 mAh·g-1, 库仑效率达到90.3%, 具有较好的循环性能. 扫描电子显微镜(SEM)结果显示, 在泡沫铜基底上制备的Cu6Sn5合金电极具有比通常的铜片基底更好的结构稳定性, 经过50 周充放电循环后无明显的脱落现象.     

Importance of nanostructure for high capacity negative electrode materials for Li-ion batteries

Sn–Co–C alloys are currently used as negative electrode materials for Li-ion batteries. A comparison between sputter deposited and mechanically alloyed Sn–Co–C materials has revealed a difference in the achieved specific capacity of materials prepared by the two methods. Only the sputtered materials reached the expected capacity even though both types of materials showed similar X-ray diffraction patterns. The structure of these materials has been described as being grains of amorphous CoSn embedded in a carbon matrix. Here, the sizes of the CoSn grains were determined using small angle neutron scattering measurements on various Sn₃₀Co₃₀C₄₀ samples. Small grain sizes, on the order of 10 Å, were obtained for the sputtered samples while grain sizes between 55 and 100 Å were obtained for samples with the same composition but prepared by mechanical alloying methods. The inability of the mechanically prepared materials to achieve their theoretical capacity may be due to the larger size of the CoSn grains.     

Facile electrochemical synthesis of hexagonal Cu2O nanotube arrays and their application

Large-scale and highly oriented single-crystalline hexagonal Cu(2)O nanotube arrays have been successfully synthesized using a two-step solution approach, which involves the electrodeposition of oriented Cu(2)O nanorods and a subsequent dissolution technique along the c axis to form a tubular structure. Herein, NH(4)Cl was found to be an effectual additive, and it can successfully realize the dissolution process of Cu(2)O from nanorods to nanotubes. The dissolution mechanism of Cu(2)O from nanorods to nanotubes was illustrated in detail. These prepared Cu(2)O nanotube arrays were characterized by SEM, EDS, XRD, XPS, and TEM. The photoluminescence (PL) spectrum of Cu(2)O nanotube arrays was also measured, and it shows there is a greater fraction of copper or oxygen vacancies in these prepared Cu(2)O nanotubes. Finally, the applications of Cu(2)O nanotube arrays for gas sensors were investigated in this paper.     

Preparation and Electrochemical Properties of the Pd-modified Cu Electrode for Nitrate Reduction in Water

The reduction of nitrate has gained renewed attention due to environmental problems like overfertilization and the increasing costs of purification of drinking water. The usual techniques (e.g. ion-exchange and biofiltration) have some disadvantages1. So …     

三维多孔Sn-Co合金负极制备及其电化学性能研究

采用化学镀方法制备三维多孔铜.以其作为集流体,借助电沉积制备三维多孔Sn-Co合金电极.X-射线衍射(XRD),扫描电镜(SEM)分析表明,以多孔铜为集流体制备的SnCo合金电极主要存在CoSn2相和纯Sn相,为三维多孔结构.充放电结果显示,三维结构SnCo合金电极比平面铜集流体上镀得的SnCo合金电极表现出更优越的充放电性能.前者的首次放电(嵌锂)容量为636.3mAh/g,充电(脱锂)容量为528.7mAh/g,首次库仑效率为83.1%,70周后容量为529.5mAh·g-1,保持率为82.6%.此外,还应用电化学阻抗初步研究了三维Sn-Co合金电极在充放电过程发生的嵌脱锂过程.     

电化学阻抗谱法研究温度对三维多孔Cu6Sn5合金电极嵌锂过程的影响

采用氢气泡为动力学模板电沉积获得多孔铜,通过热处理增强其结构稳定性,并以该多孔铜为基底电沉积获得三维多孔Cu6Sn5合金电极.采用循环伏安法研究了三维多孔Cu6Sn5合金电极的嵌/脱锂电位.采用电化学阻抗谱研究了三维多孔Cu6Sn5合金电极在不同温度下的首次嵌锂过程.结果显示,在主要的嵌锂区间内,三维多孔Cu6Sn5合...     

锂离子电池用SnZn/Cu薄膜负极材料的研究

合金型锂离子电池负极材料由于容量高、安全性好而备受关注. 采用磁控溅射法在铜箔上渡膜制备锡锌薄膜, 经热处理后得到合金薄膜电极. 薄膜热处理后, 表面活性层形成Cu3Sn中间合金. 合金薄膜是由尺寸在5 μm左右的合金颗粒构成, 而合金颗粒则由更小的尺寸在50 nm左右微粒组成, 该合金薄膜同时具有薄膜、中间合金和纳米结构材料的特征. 合金薄膜电极具有较高的充放电容量、良好的循环性能和非常高的充放电效率. 在0.01～1.0 V (vs. Li/Li＋)区间, 电极循环200周后放电容量保持在300 mAh•g－1以上, 与第一次脱锂容量相比较, 容量保持率高达91.9%, 充放电效率大于98.0%.     

Sn/Cu电极电化学还原CO2的研究

采用电沉积法制备Sn/Cu电极,由SEM观察并研究了电沉积电流密度对电极形貌的影响.在碱性三电极体系中考察了Sn/Cu电极对析氢、CO2还原的影响.发现10 mA.cm-2和15 mA.cm-2电沉积电流密度下制得的电极活性较高,尤以15 mA.cm-2时电极性能更佳,并指出了电还原CO2关键材料的结构特性.     

A combined Mössbauer spectroscopy and x-ray diffraction operando study of Sn-based composite anode materials for Li-ion accumulators

The reaction mechanisms of Li with Sn/BPO₄ composites to be used as negative electrode materials for Li-ion batteries were studied during electrochemical cycling by operando Mössbauer spectroscopy and X-ray diffraction using a specifically conceived in situ electrochemical cell. The starting composites consist of three main components: β-Sn particles as the electrochemically active species, an inactive matrix of BPO₄ and an amorphous Sn^II-borophosphate interfacial phase linking the two former components and improving the cohesion of the composite. During the first discharge, the latter Sn(II) species are first reduced to zerovalent tin forming Li-poor Li–Sn alloys. After its complete reduction, the reaction of Li continues with β-Sn leading to Li–Sn alloys increasingly rich in Li, with a final composition between those of Li₇Sn₂ and Li₁₃Sn₅. X-ray diffraction shows a progressive loss of long range order of the composites with the suppression of the diffraction peaks of the initial β-Sn and the formation of an ill-defined mixture of Li–Sn alloys. The evolution of this mechanism is investigated on going from a reference Sn/BPO₄ composite prepared by conventional ceramic methods with common micrometric BPO₄ to a new improved material prepared by carbothermal synthesis starting from nanometric BPO₄. With the new composite prepared by carbothermal synthesis, a significant improvement of the reversible capacity at the first cycle is obtained together with a slight improvement of the cycling behaviour. An additional improvement can be obtained by increasing the rate of the first discharge, and thus hampering the formation of the thermodynamically stable LiSn intermetallic.     

Nanocrystalline tin compounds/graphene nanocomposite electrodes as anode for lithium-ion battery

Nanocrystalline tin (Sn) compounds such as SnO₂, SnS₂, SnS, and graphene nanocomposites were prepared using hydrothermal method. The X-ray diffraction (XRD) pattern of the prepared nanocomposite reveals the presence of tetragonal SnO₂, hexagonal SnS₂, and orthorhombic SnS crystalline structure in the SnO₂/graphene nanosheets (GNS), SnS₂/GNS, and SnS/GNS nanocomposites, respectively. Raman spectroscopic studies of the nanocomposites confirm the existence of graphene in the nanocomposites. The transmission electron microscopy (TEM) images of the nanocomposites revealed the formation of homogeneous nanocrystalline SnO₂, SnS_2, and SnS particle. The weight ratio of graphene and Sn compound in the nanocomposite was estimated using thermogravimetric (TG) analysis. The cyclic voltammetry experiment shows the irreversible formation of Li₂O and Li₂S, and reversible lithium-ion (Li-ion) storage in Sn and GNS. The charge–discharge profile of the nanocomposite electrodes indicates the high capacity for the Li-ion storage, and the cycling study indicates the fast capacity fading due to the poor electrical conductivity of the nanocomposite electrodes. Hence, the ratio of Sn compounds (SnO₂) and GNS have been altered. Among the examined SnO₂:GNS nanocomposites ratios (35:65, 50:50, and 80:20), the nanocomposite 50:50wt% shows high Li-ion storage capacity (400 mAh/g after 25 cycles) and good cyclability. Thus, it is necessary to modify GNS and Sn compound composition in the nanocomposite to achieve good cyclability.     

Remarkably improved cycling stability of 3D porous Cu–Sn anode for lithium-ion full cells by adjusting working voltage range

Numerous studies confirm that three dimensional porous Cu–Sn (3DP Cu–Sn) anode possesses good application prospect in light of its desirable electrochemical performance on lithium ion half cells, but there are a few related systematic researches on lithium ion full cells until now, which is indispensable before its commercialization. Herein, the effects of galvanostatic charge-discharge voltage range on the cycling stability of 3DP Cu–Sn anode for lithium ion full cells are investigated systematically. The results show that the suitable charge-discharge voltage range plays a key role in improving the reversible capacity and cycling stability of the 3DP Cu–Sn||LiCoO₂ full cell, which is closely related to maintaining the electrode structure stable by controlling the amount of Li⁺ extracted and inserted. Especially, in the voltage range of 1.2–3.9 ​V, the full cell exhibits remarkably improved electrochemical properties with the high initial reversible capacity of 2.71 ​mAh cm⁻² and 71.95% capacity retention upon 80 cycles. We believe that this work can provide a significant reference for the practical application of porous Sn-based anodes.     

Synthesis and Characterization of Supported CuInSe2 Nanorod Arrays on Rigid Substrates

Copper indium diselenide nanorod arrays were electrodeposited on tungsten/silicon rigid substrates using porous anodic alumina as growth template. The porous anodic alumina templates were prepared by anodizing aluminum films which were sputtered onto the tung-sten/silicon substrates. A selective chemical etching was used to penetrate the barrier layer at the bottom of the alumina channels before electrodeposition, which enables direct elec-trical and chemical contact with the underside substrate electrode. The as-deposited sam-ples were annealed at 450 oC in vacuum. Scanning electron microscopy revealed that the nanorods were dense and compact with diameter of about 100 nm, length of approximate 1 μm, and the aspect ratio of 10. X-ray diffraction, micro-Raman spectroscopy, and highresolution transmission electron microscopy showed that chalcopyrite polycrystalline struc-ture and high purity CuInSe₂ nanorods were obtained. The grain size was large in the rod axial direction. Energy-dispersive X-ray spectroscopy showed the composition was nearly stoichiometric. The energy band gap of this nanorod arrays was analyzed by fundamental absorption spectrum and was evaluated to be 0.96 eV.     

Lithography inside Cu(OH)2 nanorods: a general route to controllable synthesis of the arrays of copper chalcogenide nanotubes with double walls

A series of well-aligned arrays of copper chalcogenide nanostructures, including Cu(7)S(4) and Cu(2-x)Se nanotubes with double walls have been successfully prepared by using Cu(OH)(2) nanorods as sacrificial templates. This new method is based on layer-by-layer chemical conversion and inward etching of the sacrificial templates, which is essentially a kind of lithography inside the Cu(OH)(2) nanorods. The key step of the process involves repeated formation of the copper chalcogenide wall and the dissolution of the Cu(OH)(2) core for two consecutive cycles. A large difference of the solubility product (Ksp) between the copper chalcogenide wall and the Cu(OH)(2) core materials is crucial for the direct replacement of one type of anions by the other. Our work provides a novel and general approach to the controllable synthesis of the arrays of copper chalcogenide nanotubes with double walls and complex hierarchies.     

Nanoimprint Lithography‐Directed Self‐Assembly of Bimetallic Iron–M (M=Palladium,Platinum) Complexes for Magnetic Patterning

Self‐assembly of d⁸ metal polypyridine systems is a well‐established approach for the creation of 1D organometallic assemblies but there are still challenges for the large‐scale construction of nanostructured patterns from these building blocks. We describe herein the use of high‐throughput nanoimprint lithography (NIL) to direct the self‐assembly of the bimetallic complexes [4′‐ferrocenyl‐(2,2′:6′,2′′‐terpyridine)M(OAc)]⁺(OAc)^? (M=Pd or Pt; OAc=acetate). Uniform nanorods are fabricated from the molecular self‐organization and evidenced by morphological characterization. More importantly, when top‐down NIL is coupled with the bottom‐up self‐assembly of the organometallic building blocks, regular arrays of nanorods can be accessed and the patterns can be controlled by changing the lithographic stamp, where the mold imposes a confinement effect on the nanorod growth. In addition, patterns consisting of the products formed after pyrolysis are studied. The resulting arrays of ferromagnetic FeM alloy nanorods suggest promising potential for the scalable production of ordered magnetic arrays and fabrication of magnetic bit‐patterned media.     

Spherical Sn–Ni–C alloy anode material with submicro/micro complex particle structure for lithium secondary batteries

Submicro/micro-scaled spherical Sn–Ni–C alloy powders synthesized from oxides of Sn and Ni via carbothermal reduction at 900 °C were examined for use as anode materials in Li-ion battery. The synthesized spherical Sn–Ni–C particles show a loose micro-sized structure and a multi-phase composition. The reaction product carbon oxide gases yielded in the carbothermal reduction process should be responsible to the loose structure characteristics of Sn–Ni–C particles. The prepared Sn–Ni–C alloy composite electrode exhibits a stable reversible capacity of 310 mA h g⁻¹ at constant current density of 100 mA g⁻¹, and can be retained at 290 mA h g⁻¹ after 25 cycles. The space existing in loose particle can accommodate the large volume changes during charge/discharge cycling. The ductile component Ni plays as a buffer to relieve the mechanical stress induced by the large volume changes upon cycling. The remained carbon can prevent the aggregation between small alloy particles. All these factors contribute greatly to the excellent cycling stability of Sn–Ni–C alloy electrode. This carbothermal reduction method is simple, cheap and mass-productive, thus suitable to large scale production of alloy anode powders used for lithium ion batteries.     

纳米Sn-Co/石墨复合材料的制备、结构和电化学性能

以化学沉积法制备Sn-Co合金纳米粒子/石墨复合材料,XRD和Ram an光谱表征物相结构,SEM观察表面形貌.结果显示,500℃高温热处理的Sn-Co/石墨复合材料,其颗粒密集均匀地分散于石墨载体上.Sn-Co合金纳米粒子颗粒直径100 nm左右.Sn-Co/石墨电极具有较高的比容量和循环寿命,这可能是该合金纳米粒子与棒状石墨间的亲合能有效地阻止Sn的脱落,Sn-Co的颗粒间隙缓冲锂嵌脱过程的结构张力,防止合金的膨胀与粉化.