Mg^2＋掺杂对锂离子正极材料Li3V2（PO4）3的影响

随着市场对锂离子电池(LIB)需求的日趋增长,对电极活性物质的要求也在朝着高能量密度、低成本、安全稳定、环境友好的方向努力,其中正极材料相对负极材料的发展较为缓慢,成为制约LIB发展的瓶颈。NASICON结构的Li3V2(PO4)3属于单斜晶系,相对金属锂具有很高的电势,理论容量高达19     

Topochemical synthesis of cobalt oxide-based porous nanostructures for high-performance lithium-ion batteries

Two kinds of topochemical conversion routes from cobalt hydroxide precursors to cobalt oxide-based porous nanostructures are presented: pyrolysis in air and hydrothermal treatment by the Kirkendall diffusion effect. These cobalt hydroxide precursors were synthesized by a simple hydrothermal approach with sodium acetate as mineralizer at 200 °C. Detailed proof indicates that the process of cobalt hydroxide precursor growth is dominated by a nucleation, dissolution, renucleation, growth, and exfoliation mechanism. By the topochemical conversion processes several Co(3)O(4) nanostructures, such as cobalt oxide-coated cobalt hydroxide carbonate nanowires, cobalt oxide nanotubes, hollow cobalt oxide spheres, and porous cobalt oxide nanowires, have been synthesized. The obtained Co(3)O(4) nanostructures have also been evaluated as the anode materials in lithium-ion batteries. It was found that the as-prepared Co(3)O(4) nanostructures exhibited high reversible capacity and good cycle performance due to their porous structure and small size.     

Conducting poly(aniline) nanotubes and nanofibers: controlled synthesis and application in lithium/poly(aniline) rechargeable batteries

The primary aim of this work was to synthesize aligned perchloric-acid-doped poly(aniline) (HClO(4)-doped PANI) nanotubes by a simple alumina template method and to investigate their application in lithium/poly(aniline) rechargeable batteries. Powder X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) analysis were used to characterize the nanostructures obtained. The second aim addressed the preparation of HClO(4)-doped PANI microspheres and nanofibers on a large scale through a modified spraying technique, since the template synthesis has limitations in mass production. The present synthesis methods are simple and can be extended to the preparation of a broad range of one-dimensional conductive polymers. Furthermore, electrochemical measurements showed that the as-prepared HClO(4)-doped PANI nanotubes exhibit better electrode performances than their commercial counterparts because they possess more active sites, higher conductivity, and relative flexibility. This indicates that HClO(4)-doped poly(aniline) nanomaterials are promising in the application of lithium/polymer rechargeable batteries.     

Cu3V2O8 hollow spheres in photocatalysis and primary lithium batteries

In this paper, Cu₃V₂O₈ hollow spheres have been successfully synthesized via a liquid precipitation method with colloidal carbon spheres as template followed by a subsequent heat treatment process. On the basis of XRD analysis, SEM observation, and TG-DSC analysis of the precursor and products, the formation mechanism of Cu₃V₂O₈ hollow spheres was proposed. UV–vis diffuse reflectance spectra showed that the Cu₃V₂O₈ hollow spheres exhibit strong absorption in a wide wavelength range from UV to visible light. The photocatalytic activity experiment indicated that the as-prepared Cu₃V₂O₈ hollow spheres exhibited good photocatalytic activity in degradation of methyl orange (MO) under 150-W xenon arc lamp light irradiation. Furthermore, electrochemical measurements showed that the Cu₃V₂O₈ hollow spheres exhibited high discharge capacity and excellent high-rate capability, indicating potential cathode candidates for primary lithium batteries used in long-term implantable cardiac defibrillators (ICDs).     

A facile synthesis of non-aqueous LiPO2F2 solution as the electrolyte additive for high performance lithium ion batteries

Constructing a reliable and favorable electrode-electrolyte interface is crucial to utilize the exceptional energy storage capability in commercial lithium-ion batteries. Here, we report a facile synthesis approach for the lithium difluorophosphate (LiPO₂F₂) solution as an effective film-forming additive via direct adding the Li₂CO₃ into LiPF₆ solution at 45 °C. Benefiting from the significantly reduced interface resistance (R_SEI) and charge transfer impedance (R_ct) of both the cathode and anode by adding the prepared LiPO₂F₂ solution into a baseline electrolyte, the cycling performance of the graphite||LiNi_0.5Mn_0.3Co_0.2O₂ pouch cell is remarkably improved under all-climate condition.     

Flutelike porous hematite nanorods and branched nanostructures: synthesis, characterisation and application for gas-sensing

Flute-like porous alpha-Fe2O3 nanorods and branched nanostructures such as pentapods and hexapods were prepared through dehydration and recrystallisation of hydrothermally synthesised beta-FeOOH precursor. Transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction analyses reveal that the nanorods, which grow along the [110] direction, have nearly hollow cavities and porous walls with a pore size of 20-50 nm. The hexapods have six symmetric arms with a diameter of 60-80 nm and length of 400-900 nm. The growth direction of the arms in the hexapod-like nanostructure is also along the [110] direction, and there is a dihedral angle of 69.5 degrees between adjacent arms. These unique iron oxide nanostructures offer the first opportunity to investigate their magnetic and gas sensing properties. The nanostructures exhibited unusual magnetic behaviour, with two different Morin temperatures under field-cooled and zero-field-cooled conditions, owing to their shape anisotropy and magnetocrystalline anisotropy. Furthermore, the alpha-Fe2O3 nanostructures show much better sensing performance towards ethanol than that of the previously reported polycrystalline nanotubes. In addition, the alpha-Fe2O3 nanostructure based sensor can selectively detect formaldehyde and acetic acid among other toxic, corrosive and irritant vapours at a low working temperature with rapid response, high sensitivity and good stability.     

The Synthesis of Porous Na3V2(PO4)3 for Sodium-Ion Storage

Na₃V₂(PO₄)₃ (NVP) has been regarded as a potential cathode material for sodium-ion batteries (SIBs) due to its excellent structural stability and rapid Na⁺ conductivity. However, its electrochemical performances are restricted by the large bulk structure and poor electronic conductivity. The construction of porous NVP materials is a powerful method to improve the electrochemical properties. This concept aims to provide an overview of recent progress of porous NVP materials for SIBs. Herein, the synthetic strategies and formation mechanisms of porous NVP materials as well as the relationship between the porous structures and electrochemical performances of NVP materials are reviewed. Furthermore, the challenges and prospects for the preparation of porous NVP materials in this field are outlined.     

A ternary phased SnO2-Fe2O3/SWCNTs nanocomposite as a high performance anode material for lithium ion batteries

A new SnO_2-Fe_2O_3/SWCNTs(single-walled carbon nanotubes) ternary nanocomposite was first synthesized by a facile hydrothermal approach.SnO_2 and Fe_2O_3 nanoparticles(NPs) were homogeneously located on the surface of SWCNTs,as confirmed by X-ray diffraction(XRD),transmission electron microscope(TEM) and energy dispersive X-ray spectroscopy(EDX).Due to the synergistic effect of different components,the as synthesized SnO_2-Fe_2O_3/SWCNTs composite as an anode material for lithium-ion batteries exhibited excellent electrochemical performance with a high capacity of 692 mAh·g~(-1) which could be maintained after 50 cycles at 200 mA·g~(-1).Even at a high rate of2000 mA·g~(-1),the capacity was still remained at 656 mAh·g~(-1).     

动力锂离子电池正极材料磷酸钒锂制备方法

锂离子电池新型正极材料的开发是当前的研究热点,其中磷酸盐材料以其结构稳定、安全性能好及资源丰富等优点备受关注。磷酸钒锂理论能量密度可达500mWh/g,具有较高的电子离子导电性、理论充放电容量及充放电电压平台,被认为是一种极具竞争优势和应用前景的动力锂离子电池正极材料。传统磷酸钒锂合成方法有固相合成法、碳热还原法、溶胶凝胶法和水热合成法等,近年来,又出现了湿法固相配位法、微波固相合成法和流变相法等新型合成方法。本文简要介绍了磷酸钒锂的结构和性能特点,对磷酸钒锂制备方法的最新研究进展进行了较为全面的阐述,并详细介绍了本研究团队近年来在磷酸钒锂材料新型合成方法方面的探索成果。同时对各种合成方法的制备工艺及材料性能进行了对比分析,并探讨了当前存在的问题及未来的研究方向。     

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...     

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.     

双金属(Sn/Ni)掺杂多孔硅微球的液相合成与电化学储锂性能

使用廉价的硅铝合金前驱体,通过简单的化学沉积方法制备了新型双金属(Sn/Ni)掺杂多孔硅微球(pSi@SnNi)。pSi@SnNi复合材料的三维多孔结构可以缓冲硅在锂化过程中的巨大体积膨胀,增加储锂活性位点。双金属(Sn/Ni)的掺杂可以提高硅的电子导电性,改进pSi的结构稳定性。由于其独特的组成和微观结构,具有适当Sn/Ni含量的pSi@SnNi复合材料显示了较大的可逆储锂容量(0.1 A·g^-1下为2 651.7 mAh·g^-1)、较高的电化学循环稳定性(1 A·g^-1下400次循环后为1 139 mAh·g^-1)和优异的倍率性能(2.5 A·g^-1下为1 235.8 mAh·g^-1)。     

双金属(Sn/Ni)掺杂多孔硅微球的液相合成与电化学储锂性能

使用廉价的硅铝合金前驱体,通过简单的化学沉积方法制备了新型双金属(Sn/Ni)掺杂多孔硅微球(pSi@SnNi)。pSi@SnNi复合材料的三维多孔结构可以缓冲硅在锂化过程中的巨大体积膨胀,增加储锂活性位点。双金属(Sn/Ni)的掺杂可以提高硅的电子导电性,改进pSi的结构稳定性。由于其独特的组成和微观结构,具有适当Sn/Ni含量的pSi@SnNi复合材料显示了较大的可逆储锂容量(0.1 A·g^-1下为2 651.7 mAh·g^-1)、较高的电化学循环稳定性(1 A·g^-1下400次循环后为1 139 mAh·g^-1)和优异的倍率性能(2.5 A·g^-1下为1 235.8 mAh·g^-1)。     

Poly(3,4-ethylenedioxythiophene)V2O5 hybrids for lithium batteries

A series of hybrid electrode materials, poly(3,4-ethylenedioxythiophene)/V₂O₅, has been synthesized using an oxidative insertion and polymerization reaction. FTIR, X-ray diffraction and transmission electron microscopy studies have shown that the incorporation of polymer between V₂O₅ slabs leads to an enhanced bidimensionality. The electrochemical lithium capacity has been increased up to ∼330 mAh/g at the second discharge in the range of 2.0–4.4 V vs. Li. This improvement of electrochemical performance compared to pristine V₂O₅ is attributed to the higher electric conductivity and enhanced bidimensionality.     

Coating of Al2O3 on layered Li(Mn1/3Ni1/3Co1/3)O2 using CO2 as green precipitant and their improved electrochemical performance for lithium ion batteries

Li(Mn_1/3Ni_1/3Co_1/3)O₂ cathode materials were fabricated by a hydroxide precursor method. Al₂O₃ was coated on the surface of the Li(Mn_1/3Ni_1/3Co_1/3)O₂ through a simple and effective one-step electrostatic self-assembly method. In the coating process, a NHCO₃-H₂CO₃ buffer was formed spontaneously when CO₂ was introduced into the NaAlO₂ solution. Compared with bare Li(Mn_1/3M_1/3Co_1/3)O₂, the surface-modified samples exhibited better cycling performance, rate capability and rate capability retention. The Al₂O₃-coated Li(Mn_1/3Ni_1/3Co_1/3)O₂ electrodes delivered a discharge capacity of about 115 mAh·g^?1 at 2 A·g^?1, but only 84 mAh·g^?1 for the bare one. The capacity retention of the Al₂O₃-coated Li(Mn_1/3Ni_1/3Co_1/3)O₂ was 90.7% after 50 cycles, about 30% higher than that of the pristine one.     

Li3V2(PO4)3/graphene nanocomposites as cathode material for lithium ion batteries

Li(3)V(2)(PO(4))(3)/graphene nanocomposites have been firstly formed on reduced graphene sheets as cathode material for lithium batteries. The nanocomposites synthesized by the sol-gel process exhibit excellent high-rate and cycling stability performance, owing to the nanoparticles connected with a current collector through the conducting graphene network.     

A facile synthesis of non-aqueous LiPO2F2 solution as the electrolyte additive for high performance lithium ion batteries

Constructing a reliable and favorable electrode-electrolyte interface is crucial to utilize the exceptional energy storage capability in commercial lithium-ion batteries. Here, we report a facile synthesis approach for the lithium difluorophosphate (LiPO₂F₂) solution as an effective film-forming additive via direct adding the Li₂CO₃ into LiPF₆ solution at 45 ℃. Benefiting from the significantly reduced interface resistance (R_SEI) and charge transfer impedance (R_ct) of both the cathode and anode by adding the prepared LiPO₂F₂ solution into a baseline electrolyte, the cycling performance of the graphite||LiNi_0.5Mn_0.3Co_0.2O₂ pouch cell is remarkably improved under all-climate condition.