Carbon anode thin films for lithium batteries

This paper describes a simple method to create carbon anode films for potential applications to the research field of lithium batteries. Carbon films were prepared using DC magneton sputtering with post-annealing process in the range from room temperature (RT) to 700 °C. Half cells assembled with lithium foils as the counter electrode and 1 M LiPF₆ in EC:DMC (1:1 v/v) electrolytic solution was used to evaluate the discharging capacity of prepared anode thin films. We showed that carbon film deposited at RT can be more suitable for an anode material than that of higher temperature annealed films above 400 °C. A variety of analysis methods including X-ray diffraction spectrometry (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were utilized to evaluate the defect density of the films; for example, the more defects on the film were identified when the carbon film was treated at a low temperature such as RT. It is envisioned that DC magnetron-sputtering with optimized process conditions can be useful for fabricating carbon based film anodes.     

锂离子电池硅基负极材料嵌锂行为的第一性原理研究

采用基于密度泛函理论的第一性原理平面波赝势方法,计算不同数量的锂离子引起的硅材料晶体结构的变化以及在嵌锂过程中形成Li_xSi(x=1、2、2.4、4.4)合金相的形成能与电子结构.采用LST/QST方法计算过渡态,模拟合金体相中的锂离子迁移过程.计算结果表明,随着嵌锂数量的增加,硅晶胞的体积在不断增大;Li_xSi合金相的形成能为负值,表明在嵌锂过程中锂离子和硅原子可以自发形成这些合金相,其中Li₇Si₃合金最容易形成;随着嵌锂量的增加,锂离子在费米能级处s轨道提供的电子数逐渐增加,锂硅合金在费米能级处的电子数量呈增大趋势,表明锂硅合金的导电性越来越优;常温下Li₂Si体相中很难直接形成锂离子空位,但锂离子空位的迁移过程很容易发生.     

锂离子电池负极材料CuSn的Li嵌入性质的研究

使用基于混合基表示的第一原理赝势法，研究了锂离子电池非碳类负极材料CuSn的Li嵌入时的形成能以及相应的电子结构.还给出了Li嵌入时的体积变化，能带结构、电子态密度以及电荷密度分布等性质, 并讨论了CuSn作为负极材料的特点.计算发现，Cu-Sn化合物在闪锌矿结构时，Li嵌入主体材料时的嵌入形成能大致在3.5eV附近. 关键词： 锂离子电池 负极材料 CuSn 电子结构     

Chitosan: A N-doped carbon source of silicon-based anode material for lithium ion batteries

Silicon/graphite/carbon (Si/G/CTS-C) composite, based on nano-silicon, flake graphite, and chitosan-derived carbon (CTS-C), was prepared by spray drying and subsequent pyrolysis. The results of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy illustrate that chitosan is a good dispersion agent and chitosan-derived carbon is N-doped. The results indicate that the initial charge capacity of Si/G/CTS-C composite is 613.9 mAh g^?1 at a current density of 100 mA g^?1 corresponding to an initial coulombic efficiency of 81.89%. Besides, the Si/G/CTS-C composite exhibits higher specific capacity, more superior rate capability, better cycling performance, and lower impedance than that of silicon/graphite/phenolic resin-derived carbon (Si/G/P-C) composite.     

Doped lithium nickel cobalt mixed oxides for the positive electrode in lithium ion batteries

Phase pure aluminium and magnesium doped lithium nickel cobalt mixed oxides Li(Ni,Co_0.1–0.2M_≤0.05)O₂ (M=Al, Mg) were synthesised in laboratory by a synthesis procedure adopted from H.C. Stark. Structural parameters were determined by Rietveld analysis of x-ray diffraction spectra. Electrochemical characterisation took place in three-electrode teflon cells and coin-type cells versus lithium metal. Thermal stability of cathodes without electrolyte was measured by DSC. For aluminium and magnesium doped lithium nickel cobalt mixed oxides Li(Ni,Co_0.1–0.2M_≤0.05)O₂ (M=Al, Mg) the layered structure is stabilised by both aluminium and magnesium. The lithium nickel disorder is decreased by cobalt and is nearly unaffected by aluminium. According to the Rietveld refinements, magnesium seems to reduce the lithium nickel disorder strongly, even though refinements are not totally reliable in this case. Initial capacity and reversibility in the first cycle are nearly unaffected by aluminium, but strongly inferred by magnesium. Both, aluminium and magnesium doping increase the cycling stability of lithium nickel cobalt mixed oxides. Increased thermal stability of charged electrodes without electrolyte by aluminium and magnesium doping seems to be due to limited delithiation. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16 – 22, 2001.     

Electrochemical properties of metal oxides as anode materials for lithium ion batteries

Some oxides have been investigated as alternative materials for Li-ion batteries. In particular, the In₂O₃ anodic compound, synthesized in our laboratory, and some commercial powders (PbO, PbO₂ and Fe₂O₃) were studied. The morphology of the oxides was analyzed by SEM investigation. The electrochemical characteristics obtained on composite thin-film electrodes based on these materials are here reported, in term of specific capacity and cyclability. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001.     

Pyrolytic carbon derived from coffee shells as anode materials for lithium batteries

Disordered carbonaceous materials have been obtained by pyrolysis of coffee shells at 800 and 900 °C with pore-forming substances such as KOH and ZnCl₂. X-ray diffraction studies revealed a carbon structure with a large number of disorganized single layer carbon sheets. The structure and morphology of the materials have been greatly varied upon the addition of porogens. The prepared carbon materials have been subjected to cycling studies. The KOH-treated products offered higher capacity with improved stability than those with untreated and ZnCl₂-treated one.     

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     

Influence of post-calcination treatment on the spinel lithium titanium oxide anode material for lithium ion batteries

The influence of post-calcination treatment on spinel Li₄Ti₅O₁₂ anode material is extensively studied combining with a ball-milling-assisted rheological phase reaction method. The post-calcinated Li₄Ti₅O₁₂ shows a well distribution with expanded gaps between particles, which are beneficial for lithium ion mobility. Electrochemical results exhibit that the post-calcinated Li₄Ti₅O₁₂ delivers an improved specific capacity and rate capability. A high discharge capacity of 172.9 mAh g^?1 and a reversible charge capacity of 171.1 mAh g^?1 can be achieved at 1 C rate, which are very close to its theoretical capacity (175 mAh g^?1). Even at the rate of 20 C, the post-calcinated Li₄Ti₅O₁₂ still delivers a quite high charge capacity of 124.5 mAh g^?1 after 50 cycles, which is much improved over that (43.9 mAh g^?1) of the pure Li₄Ti₅O₁₂ without post-calcination treatment. This excellent electrochemical performance should be ascribed to the post-calcination process, which can greatly improve the lithium ion diffusion coefficient and further enhance the electrochemical kinetics significantly.     

Metal oxide-embedded porous carbon nanoparticles as high-performance anode materials for lithium ion batteries

Conjugated microporous polymer (CMP) was used as a precursor to fabricate porous carbon nanoparticles (PCNs) embedded with different metal oxides (NiO_x, CoO_x, and MnO_x). Rate performance tests indicate that 10% MnO_x embedded PCNs (MnO_x10-PCN) show superior rate performance over PCN. MnO_x10-PCN and PCN were further investigated by XRD, XPS, TG, SEM, TEM, FT-IR, BET, cyclic voltammetry, and galvanostatic discharge–charge test. XRD and XPS results reveal that MnO and MnO₂ phase co-exist in the MnO_x10-PCN. SEM results indicate that both MnO_x10-PCN and PCN are spherical particles with a size ranging from 20 to 50 nm. TEM results imply that MnO_x nanoparticles are incorporated inside some porous carbon nanoparticles. FT-IR results indicate some residuary benzene rings remain in the MnO_x10-PCN and PCN. BET analysis reveals that pore properties of MnO_x10-PCN are very near to that of CMP. These unique features ensure MnO_x10-PCN possesses high reversible capacity, excellent rate performance, and long cycling life. MnO_x10-PCN delivers an initial reversible capacity of 986 mAh g^?1 at 0.2 C. In addition, the capacity cycled at 2 C for 700 cycles is even higher than its original capacity.     

Electrochemical performance of modified artificial graphite as anode material for lithium ion batteries

Artificial graphite anode material was modified by coating an amorphous carbon layer on the particle surface via a sol-gel and pyrolysis route. The electrochemical measurements demonstrate that appropriate carbon coating can increase the specific capacity and the initial coulombic efficiency of the graphite material, while excessive carbon coating leads to the decrease in specific capacity. Thick coating layer is obviously unfavorable for the lithium ion diffusion due to the increased diffusion distance, but the decreased specific surface area caused by carbon coating is beneficial to the decrease of initial irreversible capacity loss. The sample coated with 5 wt.% glucose exhibits a stable specific capacity of 340 mAhg^?1. Carbon coating can remarkably enhance the rate capability of the graphite anode material, which is mainly attributed to the increased diffusion coefficient of lithium ion.     

Nanoporous carbon microspheres as anode material for enhanced capacity of lithium ion batteries

Nanoporous carbon microspheres (NCMs) are prepared by a one-step carbonizing and activating resorcinol?formaldehyde polymer spheres (RFs) in inert and CO₂ atmosphere for anode materials of lithium-ion batteries (LIBs). Compared with RFs carbon microspheres (RF-C), after activating with hot CO₂, the NCMs with porous structure and high BET surface area of 2798.8 m² g^?1, which provides abundant lithium-ion storage site as well as stable lithium-ion transport channel. When RF-C and NCM are used to anode material for LIBs, at the same current density of 210 mA g^?1, the initial specific discharge capacity are 482.4 and 2575.992 mA h g^?1, respectively; after 50 cycles, the maintain capacity are 429.379 and 926.654 mA h g^?1, respectively. The porous spherical structure of NCM possesses noticeably lithium-ion storage capability, which exhibits high discharge capacity and excellent cycling stability at different current density. The CO₂ activating carbonaceous materials used in anode materials can tremendously enhance the capacity storage, which provides a promising modification strategy to improve the storage capacity and cyclic stability of carbonaceous anode materials for LIBs.     

Synthesis and electrochemical properties of SnS as possible anode material for lithium batteries

Tin monosulfide, SnS particles were synthesized at 950 °C using a simple melt mixing. The as prepared materials were subjected to XRD, SEM and EDAX analyses. The CR 2032-type coin cell composed of Li/SnS was assembled and its cycling profile was examined. The cell delivered an initial discharge capacity of 956 mAh/g at its first cycle and fades subsequently in the following cycles. The formation of Li₂CO₃ in the solid electrolyte interface (SEI) was identified by FT-IR analysis. Impedance spectroscopic study on Li/SnS cells revealed an increase in the value of charge transfer resistance “R_ct” upon cycling and is attributed to the breaking of inter-particle contact caused by the volume expansion.     

硅功能化石墨烯负极材料的粗粒模型

硅功能化石墨烯(硅化烯)作为锂离子电池的负极材料, 一旦发生分层或粉化等损伤现象, 会严重地降低材料的电子输运能力和储锂容量, 减少电池的使用寿命, 因此要求负极材料具有较强的力学可靠性. 考虑到传统分子动力学方法的模拟尺度很难达到硅化烯负极材料的真实尺度, 首先采用Tersoff 势函数和Lennard-Jones 势函数建立了多种硅化烯的全原子数值模型, 计算材料的各种弹性模量和吸附能; 然后采用珠子-弹簧结构, 根据力学平衡条件和能量守恒定律, 结合全原子模型的计算结果, 建立了硅化烯粗粒模型及其系统的能量方程; 最后, 通过对比石墨烯粗粒模型与其全原子模型的拉伸性能, 验证了硅化烯粗粒模型的有效性.     

Lithium insertion studies on boron-doped diamond as a possible anode material for lithium batteries

Boron-doped diamond (BDD) was prepared by the hot filament chemical vapor deposition method. The prepared samples were subjected to X-ray diffraction, scanning electron microscopy, and Raman spectroscopy studies. The BDD composite electrode/Li cell has been assembled, and its cycling behavior was studied. The BDD possesses large sp² sites, which effectively participate in the lithium storage process. Furthermore, nanocrystalline tin (Sn) particles were prepared by the chemical reduction method. The addition of nanotin with the BDD-active material greatly enhances the cyclability of the cell. An erratum to this article can be found at     

Distinctive slit-shaped porous carbon encapsulating phosphorus as a promising anode material for lithium batteries

A distinctive structure of carbon materials for Li-ion batteries is proposed for the preparation of red phosphorus-carbon composites. The slit-shaped porous carbon is observed with aggregation of plate-like particles, whose isotherm belongs to the H3 of type IV. The density functional theory (DFT) method reveals the presence of micro-mesopores in the 0.5–5 nm size range. The unique size distribution plays an important role in adsorbing phosphorus and electrochemical performance. The phosphorus-slit-shaped porous carbon composite shows initial capacity of 2588 mAh g^?1, reversible capacity of 1359 mAh g^?1 at a current density of 100 mA g^?1. It shows an excellent coulombic efficiency of ～99 % after 50 cycles.     

Effect of carbon nanotubes on the anode performance of natural graphite for lithium ion batteries

A comparative investigation was carried out on carbon black and multiwalled carbon nanotubes as conductive additives in spherical natural graphite for lithium ion batteries. Scanning electron microscopy images showed that carbon nanotubes interlaced graphite particles in series to form a three-dimensional network. The constant current charge-discharge experiments showed that carbon nanotubes were more effective in improving reversible capacity and cycle stability. The reversible capacity was improved to 366 mAh/g and the cycle stability was improved effectively when carbon nanotubes were used. The research is of potential interest to the application of carbon nanotubes as conductive additives in anode materials for high-power lithium ion batteries.     

Hollow structured Sn-Co nanospheres by galvanic replacement reaction as high-performance anode for lithium ion batteries

Hollow Sn-Co nanospheres have been fabricated by galvanic replacement reaction. In particular, the hollow resultants with different shell thickness and void space can be obtained using sacrificial templates with different sizes. The structural evolution of Sn-Co hollow microspheres and structure changes during charge/discharge process were studied using XRD, SEM, and TEM. As an anodic material, the hollow resultants with thin shell and relatively large void space exhibited a good reversible capacity of 502 mAh g^?1 at a current density of 100 mA g^?1 and a coulomb efficiency over 99 % after 100 cycles. The contributions of the hollow structure and the inactive Co element to electrochemical performance were verified by galvanostatic charge/discharge cycling, electrochemical impedance spectroscope, and TEM measurements. A possible mechanism for hollow structure with different shell thickness to alleviate the volume change was proposed.     

One-pot facile synthesis of CuS/graphene composite as anode materials for lithium ion batteries

CuS/graphene composite has been synthesized by the one-pot hydrothermal method using thiourea as the sulfur source and reducing agent. The formation of CuS nanoparticles and the reduction of graphene oxide occur simultaneously during the hydrothermal process, which enables a uniform dispersion of CuS nanoparticles on the graphene nanosheets. The electrochemical performance of CuS/graphene composite was studied as anode materials for lithium ion batteries. The obtained CuS/graphene composite exhibits a relative high reversible capacity and good cycling stability. The good electrochemical performance of CuS/graphene composite can be attributed to graphene, which improves the electronic conductivity of composite and enhances the interfacial stability of electrode and electrolyte.     

A novel LiSnVO4 anode material for lithium-ion batteries

Ionics - In this work, a new material LiSnVO4 has been prepared via sol-gel method utilizing ammonium metavanadate, acetates of tin and lithium as starting materials, and nitric acid and oxalic...