Electrochemical properties of SnO2 nanorods as anode materials in lithium-ion battery

Well-dispersed SnO2 nanorods with diameter of 4-15 nm and length of 100-200 nm are synthesised through a hydrothermal route and their potential as anode materials in lithium-ion batteries is investigated. The observed initial discharge capacity is as high as 1778 mA·h/g, much higher than the theoretical value of the bulk SnO2 (1494 mA·h/g). During the following 15 cycles, the reversible capacity decreases from 929 to 576 mA·h/g with a fading rate of 3.5% per cycle. The fading mechanism is discussed. Serious capacity fading can be avoided by reducing the cycling voltages from 0.05-3.0 to 0.4-1.2 V. At the end, SnO2 nanorods with much smaller size are synthesized and their performance as anode materials is studied. The size effect on the electrochemical properties is briefly discussed.     

Nanoporous silicon flakes as anode active material for lithium-ion batteries

Nanoporous-silicon (np-Si) flakes were prepared using a combination of an electrochemical etching process and an ultra-sonication treatment and the electrochemical properties were studied as an anode active material for rechargeable lithium-ion batteries (LIBs). This fabrication method is a simple, reproducible, and cost effective way to make high-performance Si-based anode active materials in LIBs. The anode based on np-Si flakes exhibited a higher performances (lower capacity fade rate, stability and excellent rate capability at high C-rate) than the anode based on Si nanowires. The excellent performance of the np-Si flake anode was attributed to the hollowness (nanoporous structure) of the anode active material, which allowed it to accommodate a large volume change during cycling.     

A review of research on hematite as anode material for lithium-ion batteries

Hematite (α-Fe₂O₃) nanomaterials have been investigated intensively as a promising anode material for Li-ion batteries due to their advantages such as high theoretical capacity, low cost, environmental friendliness, high resistance to corrosion, etc. However, their practical application is hampered by poor capacity retention, low Coulombic efficiency, and poor high-rate capacity. To overcome these drawbacks, many effective works have been proposed. This review focuses first on the present status of α-Fe₂O₃ nanomaterials in the field of Li-ion batteries including their features, synthesized methods, modification, application and then on their near future development.     

Carbon-coated silicon/crumpled graphene composite as anode material for lithium-ion batteries

Silicon is a promising anode material for high-capacity Li-ion batteries (LIBs). However, its insulating property and large volume change during the lithiation/delithiation process result in poor cycling stability and in pulverization of Si. In this work, glucose-derived carbon-coated Si nanoparticles (C–Si NPs) are in conjunction with crumpled graphene (cGr) particles by a spray-drying method to prepare a novel composite (C–Si/cGr) material. The prepared C–Si NPs are uniformly embedded in the ridges of the cGr particles. The carbon layer of C–Si can make a good contact with the graphene sheet, resulting in enhanced electrical conductivity and fast charge transfer. In addition, the unique crumpled structure of the cGr can buffer the large volume change upon cycling process and facilitate the diffusion of electrolyte into the composite material. When employed as an anode electrode of LIBs, the C–Si/cGr composites deliver enhanced electrochemical performance, including stable cycling with a discharge capacity of 790 mAh·g⁻¹ after 100 cycles and a rate capability of 654 mAh·g⁻¹ at 2C. The synergistic effect of the carbon layer coating of Si NPs and the crumpled structure of the cGr particles results in a composite with improved the electrochemical performance, which is likely related to its high electrical conductivity and good mechanical stability of composite material.     

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...     

Synthesis of three-dimensional cross-linked MnO@C composite as high-performance anode material for lithium-ion batteries

MnO@C composites with three-dimensional cross-linked structure were designed and fabricated through hydrothermal treatment. Cation exchange resin was used as the precursor to create a three-dimensional cross-linked porous carbon structure, which was evenly decorated by nanosized MnO particles. When compared with pristine MnO, those MnO@C composites showed much better stability during charge-discharge cycling, retaining a specific capacity of 615 mAh g^?1 (62.5 wt% MnO) after 100 cycles at a current density of 0.2 A g^?1. This could be ascribed to the special three-dimensional cross-linked porous carbon that not only accelerated the transport of Li⁺ ions but also buffered the volume change and prevented agglomeration of MnO particles during the repeated lithiation and delithiation process.     

Hierarchical nanostructure CuO with peach kernel-like morphology as anode material for lithium-ion batteries

Copper oxide particles with different morphology (flower-like, peach kernel-like, and dandelion-like) are prepared with hydrothermal method by adjusting chitosan ((C₆H₁₁NO₄)_n) concentration in aqueous mixed solutions of ammonia and Cu(NO₃)₂. Various morphologies of porous cupric oxide (CuO) particles are formed by agglomerated nanosheet primary particles and lead to different electrochemical performance of electrodes. The peach kernel-shaped CuO exhibits high reversible capacity and rate capability. The reversible capacity is 722.7 mAh g^?1 at 0.1 C in the first cycle and 339 mAh g^?1 after 50 cycles at 0.2, 0.5, 1.0, and 2.0 C ratio. The higher reversible capacities and good cycling performance are attributed to the larger specific surface area, leading to better contact between CuO and electrolyte.     

Electrochemical properties of TiO2 nanotube-Li4Ti5O12 composite anodes for lithium-ion batteries

For application as an anode material in lithium batteries, composite anodes consisting of TiO₂ nanotubes (TNT) and Li₄Ti₅O₁₂ (LTO) nanocrystalline particles are prepared by hydrothermal reaction of rutile TiO₂ particles, physical blending with LTO, and subsequent heat treatment at 300 °C. The TNT-LTO composites with varying the composition are characterized by electron microscopy, X-ray diffraction, potentiostatic cyclic voltammetry, and galvanostatic charge-discharge tests at various current rates. With higher LTO content, short TNTs with the average tube diameter of 10 nm are distributed among the potato-shaped LTO particles with the average diameter of 200 nm. At higher content of TNT, however, the LTO particles are sparsely distributed in the fibrillar aggregates of TNT with more lengthened image. As a result, the samples of TNT:LTO = 2:8 and 4:6 show superior cycle performance and high-rate capability, mainly due to their higher electrode densities to yield nanotubular TNT distributed on and supported by potato-shaped LTO nanoparticles.     

The effects of Li2CO3 particle size on the properties of lithium titanate as anode material for lithium-ion batteries

Spinel structured Li₄Ti₅O₁₂ was synthesized by a solid-state method using TiO₂ and Li₂CO₃ as starting materials. High-energy ball milling was used to obtain the Li₂CO₃ samples with different particle size. Then, the effects of Li₂CO₃ particle size on the structure, morphology, and electrochemical performance of Li₄Ti₅O₁₂ samples were investigated in detail. The samples were characterized by TG/DTA analysis, X-ray diffraction, scanning electron microscopy and electrochemical tests, respectively. The results indicate that fine Li₂CO₃ particles will promote the interfacial reaction between Li₂CO₃ and TiO₂ in solid-state reaction. The crystallinity and particle size of Li₄Ti₅O₁₂ depend on the particle size of Li₂CO₃. Electrochemical tests show that Li₄Ti₅O₁₂ samples synthesized by fine Li₂CO₃ particles exhibit better rate capacity and cycle performance.     

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     

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.     

Synthesis and electrochemical investigation of highly dispersed ZnO nanoparticles as anode material for lithium-ion batteries

Highly dispersed ZnO nanoparticles were prepared by a versatile and scalable sol-gel synthetic technique. High-resolution transmission electronic microscopy (HRTEM) showed that the as-prepared ZnO nanoparticles are spherical in shape and exhibit a uniform particle size distribution with the average size of about 7 nm. Electrochemical properties of the resulting ZnO were evaluated by galvanostatic discharge/charge cycling as anode for lithium-ion battery. A reversible capacity of 1652 mAh g^?1 was delivered at the initial cycle and a capacity of 318 mAh g^?1 was remained after 100 cycles. Furthermore, the system could deliver a reversible capacity of 229 mAh g^?1 even at a high current density of 1.5 C. This outstanding electrochemical performance could be attributed to the nano-sized features of highly dispersed ZnO particles allowing for the better accommodation of large strains caused by particle expansion/shrinkage along with providing shorter diffusion paths for Li⁺ ions upon insertion/deinsertion.     

Synthesis and performance of Li2NiTi3O8 as a new anode material for lithium-ion batteries

The titanate spinel Li₂NiTi₃O₈ is proposed for the first time as a new anode for lithium-ion batteries and successfully synthesized via a facile ball-milling assisted solid-state reaction method. The sample is characterized by X-ray diffraction patterns (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), galvanostatic charge–discharge tests, cyclic voltammetry (CV) tests, and electrochemical impedance spectroscopy (EIS). The results reveal that the Li₂NiTi₃O₈ nanoparticles have well-distributed morphology, and the particle size ranges between 100 and 300 nm. Although the initial coulombic efficiency is only 56.3 %, the Li₂NiTi₃O₈ electrode still exhibits a high rate capability and excellent cycling stability. The Li₂NiTi₃O₈ anode provides a large capacity of 212.3 mAh g^?1 at 0.1 A g^?1 after 10 cycle, which is close to its theoretical capacity (223.6 mAh g^?1). Even after 100 cycles, it still delivers a quite high capacity of 203.98 mAh g^?1, with no significant capacity fading. This indicates that the as-synthesized Li₂NiTi₃O₈ material is a promising anode material for lithium-ion batteries.     

Double-walled core-shell structured Si@SiO2@C nanocomposite as anode for lithium-ion batteries

Double-walled core-shell structured Si@SiO₂@C nanocomposite has been prepared by calcination of silicon nanoparticles in air and subsequent carbon coating. The obtained Si@SiO₂@C nanocomposite demonstrates a reversible specific capacity of about 786 mAh g^?1 after 100 cycles at a current density of 100 mA g^?1 with a capacity fading of 0.13 % per cycle. The enhanced electrochemical performance can be due to that the double walls of carbon and SiO₂ improve the electronic conductivity and enhance the compatibility of electrode materials and electrolyte as a result of accommodating the significant volumetric change during cycles. The interlayer SiO₂ may release the mechanical strain and enhance the interfacial adhesion between carbon shell and silicon core.     

Sn and SnO2-graphene composites as anode materials for lithium-ion batteries

Sn and SnO₂-graphene composites were synthesized using hydrothermal process, followed by annealing in Ar/H₂ atmosphere, and characterized using x-ray diffraction, scanning electron microscopy, and transition electron microscopy. The results indicated that the polycrystalline metallic Sn forms nanospheres with a diameter of 100?～?300 nm, while the SnO₂ nanoparticles are much smaller with a size below 15 nm, which adsorb tightly on the surface of graphene sheets. The Sn and SnO₂-gaphene composites showed good electrochemical performance. After 55 charging/discharging cycles, the capacity remains above 440 mAh/g at a cycling rate of 400 mA/g and the coulombic efficiency is 99.1 %. The good electrochemical properties of the composites are partially contributed to the graphene component with good mechanical flexibility and electrical conductivity, which is an excellent carbon matrix for dispersing the Sn and SnO₂ nanostructures and provides the electron transport pathways as well.     

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.     

Electrochemical performance of surfactant-processed LiFePO4 as a cathode material for lithium-ion rechargeable batteries

This study focuses on the effect of addition of surfactant as a dispersing agent during vibratory ball milling of LiFePO₄ (LFP) precursor materials on the electrochemical performance of solid-state reaction synthesized LFP for lithium-ion battery cathode material. LFP particles formed after calcinations of ball milled LFP precursors (Li₂CO₃, FeC₂O₄, and NH₄H₂PO₄) showed better size uniformity, morphology control, and reduced particle size when anionic surfactant (Avanel S-150) was used. The specific surface area of LFP particles increased by approximately twofold on addition of surfactant during milling. These particles showed significantly enhanced cyclic performance during charge/discharge due to a reduced polarization of electrode material. Electrodes fabricated from LFP particles by conventional milling process showed a 22 % decrease in capacity after 50 cycles, whereas the performance of electrode prepared by surfactant processed LFP showed only 3 % loss in capacity. The LFP particles were characterized using XRD, FE-SEM, particle size distribution, density measurement, and BET-specific surface area measurement. Electrochemical impedance spectra and galvanostatic charge/discharge test were performed for the electrochemical performance using coin-type cell.     

Facile preparation of SGC composite as anode for lithium-ion batteries

The silicon/graphite/carbon (SGC) composite was successfully prepared by ball-milling combined with pyrolysis technology using nanosilicon, graphite, and phenolic resin as raw materials. The structure and morphology of the as-prepared materials are characterized by X–ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). Meanwhile, the electrochemical performance is tested by constant current charge–discharge technique, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) measurements. The electrodes exhibit not only high initial specific capacity at a current density of 100 mA g^?1, but also good capacity retention in the following 50 cycles. The EIS results indicate that the electrodes show low charge transfer impedance R_sf?+?R_ct. The results promote the as-prepared SGC material as a promising anode for commercial use.     

Sn-Sb and Sn-Bi alloys as anode materials for lithium-ion batteries

Sn/SnSb, Sn/Bi, and Sn/SnSb/Bi multi-phase materials were synthesised via reduction of cationic precursors with NaBH₄ and with Zn, and were tested for their suitability as anode materials for Li-ion batteries by galvanostatic cycling. The rapid reduction with NaBH₄ yielded the finer materials with the better cycling stabilities, whereas the reduction with Zn yielded the purer materials with the lower irreversible capacities in the first cycle. Reversible capacities of ∼ 600 mAh g⁻¹, ∼ 350 – 400 mAh g⁻¹, and ∼ 500 mAh g⁻¹ were obtained for Sn/SnSb, Sn/Bi, and Sn/SnSb/Bi, respectively. The cycling stability of the materials decreased in the order Sn/SnSb>Sn/SnSb/Bi>Sn/Bi, which is in part attributed to the presence / absence of intermetallic phases which undergo phase-separation during lithiation. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001.     

Nanostructured WO3 thin film as a new anode material for lithium-ion batteries

Nanostructured WO₃ thin film has been successfully fabricated by radio-frequency magnetron sputtering method and its electrochemistry with lithium was investigated for the first time. The reversible discharge capacity of WO₃/Li cells cycled between 0.01 V and 4.0 V was found above 626 mAh/g during the first 60 cycles at the current density 0.02 mA/cm². By using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and selected-area electron diffraction measurements, the reversible conversion of WO₃ into nanosized metal W and Li₂O was revealed. The high reversible capacity and good recyclability of WO₃ electrode made it become a promising cathode material for future rechargeable lithium batteries.