Lithium storage in hollow spherical ZnFe2O4 as anode materials for lithium ion batteries

Hollow microspheres composed of phase-pure ZnFe₂O₄ nanoparticles (hierarchically structured) have been prepared by hydrothermal reaction. The unique hollow spherical structure significantly increases the specific capacity and improves capacity retention of this material. The product of each phase transition during initial discharge (ZnFe₂O₄ ? Li_0.5ZnFe₂O₄ ? Li₂ZnFe₂O₄ → Li₂O + Li–Zn + Fe) and their structural reversibility are recognized by X-ray diffraction and electrochemical characterization. The products of the deeply discharged (Li–Zn alloy and Fe) and recharged materials (Fe₂O₃) were clarified based on high resolution transmission electron microscopic technique and first-principle calculations.     

Co3O4@graphene composites as anode materials for high-performance lithium ion batteries

This paper reports on the synthesis of Co(3)O(4)@graphene composites (CGC) and their applications as anode materials in lithium ion batteries (LIBs). Through a chemical deposition method, Co(3)O(4) nanoparticles (NPs) with sizes in the range of 10-30 nm were homogeneously dispersed onto graphene sheets. Due to their high electrical conductivity, the graphene sheets in the CGC improved the electrical conductivity and the structure stability of CGC. CGC displayed a superior performance in LIBs with a large reversible capacity value of 941 mA hg(-1) in the initial cycle with a large current density and an excellent cyclic performance of 740 mA hg(-1) after 60 cycles, corresponding to 88.3% of the theoretical value of CGC, owing to the interactions between graphene sheets and Co(3)O(4) NPs anchored on the graphene sheets. This synthesis approach may find its application in the design and synthesis of novel electrode materials used in LIBs.     

SnSe2 nanoplate-graphene composites as anode materials for lithium ion batteries

Through a solution approach, SnSe(2) nanoplate-graphene composites were prepared and applied as anode materials in lithium ion batteries, showing promising storage performance superior to SnSe(2) nanoplates or graphene alone.     

Template-free fabrication of porous CuCo2O4 hollow spheres and their application in lithium ion batteries

Journal of Solid State Electrochemistry - In this study, we develop a simple template-free strategy to fabricate uniform porous CuCo2O4 hollow spheres. The shells of the as-synthesized CuCo2O4...     

Silver-coated TiO2 nanostructured anode materials for lithium ion batteries

Anatase TiO₂ nanoribbons/nanotubes (TiO₂-NRTs) have been synthesised successfully via a reflux method followed by drying in a vacuum oven, and then, silver-coated TiO₂ NRTs (Ag/TiO₂-NRTs) were prepared by coating silver particles onto the TiO₂-NRTs surface by the traditional silver mirror reaction. The physical properties of the synthesised products were examined in detail using X-ray diffraction, field emission gun scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy, respectively. The results indicated that the Ag nanoparticles were uniformly deposited on the surface of the TiO₂ nanoribbons/nanotubes. The electrochemical properties were investigated by a variety of techniques. The rate capability and cycle durability for the Ag/TiO₂-NRTs were improved compared with TiO₂-NRTs. It is speculated that the Ag-coated TiO₂ nanoribbons/nanotubes are an effective anode candidate for lithium ion batteries.     

Single-walled carbon nanohorns coated with Fe2O3 as a superior anode material for lithium ion batteries

A novel composite of Fe(2)O(3) and single-walled carbon nanohorns (SWCNHs) was firstly developed via a simple hydrothermal method. As an anode material for lithium ion batteries, a Fe(2)O(3)/SWCNHs composite shows excellent rate performance and cycle stability, even at a high current density of 1000 mA g(-1).     

Graphene-encapsulated Fe3O4 nanoparticles with 3D laminated structure as superior anode in lithium ion batteries

Fe₃O₄–graphene composites with three‐dimensional laminated structures have been synthesised by a simple in situ hydrothermal method. From field‐emission and transmission electron microscopy results, the Fe₃O₄ nanoparticles, around 3–15 nm in size, are highly encapsulated in a graphene nanosheet matrix. The reversible Li‐cycling properties of Fe₃O₄–graphene have been evaluated by galvanostatic discharge–charge cycling, cyclic voltammetry and impedance spectroscopy. Results show that the Fe₃O₄–graphene nanocomposite with a graphene content of 38.0 wt % exhibits a stable capacity of about 650 mAh g^?1 with no noticeable fading for up to 100 cycles in the voltage range of 0.0–3.0 V. The superior performance of Fe₃O₄–graphene is clearly established by comparison of the results with those from bare Fe₃O₄. The graphene nanosheets in the composite materials could act not only as lithium storage active materials, but also as an electronically conductive matrix to improve the electrochemical performance of Fe₃O₄.     

Electrospun porous SnO2 nanotubes as high capacity anode materials for lithium ion batteries

Porous SnO₂ nanotubes were prepared via electrospinning followed by calcination in air. As anode materials for lithium ion batteries, the porous nanotubes delivered a high discharge capacity of 807 mAh g^? 1 after 50 cycles. Even after cycled at high rates, the electrode still retained a high fraction of its theoretical capacity. Such excellent performances of porous SnO₂ nanotubes could be attributed to the porous and hollow structure which facilitated liquid electrolyte diffusion into the bulk materials and buffered large volume changes during lithium ions insertion/extraction. Furthermore, the nanoparticles of nanotubes provided the shorter diffusion length for lithium ions insertion which benefited in retaining the structural stability and good rate performance. Our results demonstrated that this simple method could be extended for the synthesis of porous metal oxide nanotubes with high performances in the applications of lithium ion batteries and other fields.     

Sn-Al合金作为锂电池负极材料的第一性原理研究

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了不同Al含量的固溶体Sn-Al合金的总能量与电子结构,得到Sn0.7Al0.3合金比例最适合用于锂离子电池Sn基合金材料,并对Sn0.7Al0.3合金嵌锂后的各种物理性质和电化学性质进行了理论计算,发现该固溶体合金相具有较稳定的电化学嵌锂电位和良好的充放电循环性能.同时采用磁控溅射制备了该合金薄膜材料,测试结果与理论计算具有较好的一致性.     

Carbon anode materials from polysiloxanes for lithium ion batteries

Three kinds of silicon-containing disordered carbons have been prepared by pyrolysis of polysiloxanes with different amounts of phenyl side groups. X-ray powder diffraction, X-ray photoelectron spectroscopy and electrochemical capacity measurements were performed to study their behaviors. Graphite crystallites, micropores, and silicon species affect their electrochemical performances. All of them present high reversible capacities, >372 mAh/g. Since the graphite crystallites are very small, they contribute very little to reversible capacity. The number of micropores produced by gas emission during the heat-treatment process decides whether they exhibit reversible capacity. Si mainly exists in the form C–Si–O and influences the irreversible capacity. There is no evident capacity fading in the first ten cycles, indicating promising properties for these disordered carbons.     

Polyaniline encapsulated silicon nanocomposite as high-performance anode materials for lithium ion batteries

Polyaniline encapsulated silicon (Si/PANI) nanocomposite as anode materials for high-capacity lithium ion batteries has been prepared by an in situ chemical polymerization of aniline monomer in the suspension of Si nanoparticles. The obtained Si/PANI nanocomposite demonstrates a reversible specific capacity of 840 mAh g^?1 after 100 cycles at a rate of 100 mA g^?1 and excellent cycling stability. The enhanced electrochemical performance can be due to that the polyaniline (PANI) matrix offers a continuous electrically conductive network as well as enhances the compatibility of electrode materials and electrolyte as a result of suppressing volume stress of Si during cycles and preventing the agglomeration of Si nanoparticles.     

Si–AB5 composites as anode materials for lithium ion batteries

The Si–AB₅ (MmNi_3.6Co_0.7Al_0.3Mn_0.4 alloy) composites with a high tap density as anode materials for lithium-ion batteries were synthesized by ball-milling. Si nanoparticles are distributed homogeneously on the surface of the AB₅ matrix. The electrochemical performance of the Si–AB₅ composites as a function of Si content was investigated. It is demonstrated that the Si–AB₅ composite delivers a larger reversible capacity and better cycle ability because the inactive AB₅ alloy can accommodate the large volume changes of Si nanoparticles distributed on the surface of the Si–AB₅ composite during cycling. In particular, the Si–AB₅ composite containing 20 wt% Si with the high tap density of 2.8 g/cm³ obtained after ball-milling for 11 h exhibits an initial and maximum reversible (charge) capacity of 370 and 385 mAh/g. The high capacity retention can be achieved after 50 cycles in the potential range from 0.02 to 1.5 V.     

Submicro-sized porous SiO2/C and SiO2/C/graphene spheres for lithium ion batteries

Journal of Solid State Electrochemistry - In order to improve electrochemical performance of inert SiO2 anode for lithium ion batteries, submicro-sized porous SiO2/C and SiO2/C/graphene spheres...     

Graphene anchored with ZnFe2O4 nanoparticles as a high-capacity anode material for lithium-ion batteries

Heterostructured ZnFe₂O₄–graphene nanocomposites are synthesized by a facile hydrothermal method. The as-prepared ZnFe₂O₄–graphene nanocomposites are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) analysis and galvanostatic charge and discharge measurements. Compared with the pure ZnFe₂O₄ nanoparticles, the ZnFe₂O₄–graphene nanocomposites exhibit much larger reversible capacity up to 980 mAh g⁻¹, greatly improved cycling stability, and excellent rate capability. The superior electrochemical performance of the ZnFe₂O₄–graphene nanocomposites could be attributed to the synergetic effect between the conducting graphene nanosheets and the ZnFe₂O₄ nanoparticles.     

Reversible lithium storage in Na2Li2Ti6O14 as anode for lithium ion batteries

The sodium lithium titanate with composition Na₂Li₂Ti₆O₁₄ has been synthesized by a sol–gel method. Thermogravimetric analysis and differential thermal analysis (TG–DTA) of the thermal decomposition process of the precursor and X-ray diffraction (XRD) data indicate the crystallization of sodium lithium titanate has occurred at about 600 °C. Electrochemical lithium insertion into Na₂Li₂Ti₆O₁₄ for lithium ion battery has been investigated for the first time. These results indicate the discharge and charge potential plateaus are about 1.3 V. The initial discharge capacity is much higher than the charge capacity and irreversible capacity exists in the voltage window 1–3 V. Subsequently, the discharge capacity decreases slowly, but the charge capacity increases slightly in the following cycles. After a few cycles, the specific capacity remains almost constant values and the sample exhibits the excellent retention of capacity on cycling.     

High capacity silicon/carbon composite anode materials for lithium ion batteries

Silicon/carbon composite materials are prepared by pyrolysis of pitch embedded with graphite and silicon powders. As anode for lithium ion batteries, its initial reversible capacity is 800–900 mAh/g at 0.25 mA/cm² in a voltage range of 0.02/1.5 V vs. Li. The material modification by adding a small amount of CaCO₃ into precursor improves the initial reversibility (η₁=84%) and suppresses the capacity fade upon cycling. A little higher insertion voltage of the composites than commercial CMS anode material improves the cell safety in the high rate charging process.     

Morphology-controllable synthesis of LiMn2O4 particles as cathode materials of lithium batteries

We reported a new method for the preparation of morphology-controllable LiMn₂O₄ particles. In this method, dimension-different MnO₂ nanowires synthesized hydrothermally by adjusting the reaction temperature were used as the precursor. The morphology and structure of the resulting products were characterized with scanning electron microscope and X-ray diffraction, and the performances of the prepared LiMn₂O₄ samples as cathode material of lithium batteries were investigated by cyclic voltammetry and galvanostatic charge/discharge test. The results indicate that the morphology of LiMn₂O₄ transforms from tridimensional particle (TP) to unidimensional rod (UR) through quadrate lamina (QL) with increasing the diameter and length of MnO₂ nanowires. Although the cyclic stabilities of LiMn₂O₄-TP, LiMn₂O₄-QL, and LiMn₂O₄-UR are very close (the 0.1 C capacity after 50 cycles is 101, 93, and 99 mAh g^?1 at 25 °C, and 84, 78, and 82 mAh g^?1 at 50 °C, respectively), LiMn₂O₄-QL delivers much higher rate capacity (about 70 mAh g^?1 at 5 C and 30 mAh g^?1 at 10 C) than LiMn₂O₄-TP and LiMn₂O₄-UR (about 20 mAh g^?1 at 5 C, 3 mAh g^?1 at 10 C, 25 mAh g^?1 at 5 C, and 3 mAh g^?1 at 10 C).     

Facile synthesis of porous MnO/C nanotubes as a high capacity anode material for lithium ion batteries

Porous MnO/C nanotubes are synthesized by a facile hydrothermal method followed by thermal annealing, and possess excellent cyclability and high rate capability as an anode for lithium ion batteries.