Electrochemical performance and ex situ analysis of ZnMn2O4 nanowires as anode materials for lithium rechargeable batteries

One-dimensional ZnMn₂O₄ nanowires have been prepared and investigated as anode materials in Li rechargeable batteries. The highly crystalline ZnMn₂O₄ nanowires about 15 nm in width and 500 nm in length showed a high specific capacity of about 650 mAh·g⁻¹ at a current rate of 100 mA·g⁻¹ after 40 cycles. They also exhibited high power capability at elevated current rates, i.e., 450 and 350 mAh·g⁻¹ at current rates of 500 and 1000 mA·g⁻¹, respectively. Formation of Mn₃O₄ and ZnO phases was identified by ex situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies after the initial discharge-charge cycle, which indicates that the ZnMn₂O₄ phase was converted to a nanocomposite of Mn₃O₄ and ZnO phases immediately after the electrochemical conversion reaction.     

Mechanochemical synthesis of SnO-B2O3 glassy anode materials for rechargeable lithium batteries

The xSnO·(100 ? x)B₂O₃ (0 ≦ x ≦ 80) glasses were successfully prepared by a mechanical milling technique. The glass with 40 mol% SnO showed the maximum glass transition temperature of 347°C. The SnO-B₂O₃ milled glasses consisted of both BO₃ and BO₄ units, and the fraction of BO₄ units was maximized at the composition of 50 mol% SnO. The electrochemical properties of the milled glasses were examined using a simple three electrodes cell with a conventional liquid electrolyte. The glasses with high SnO content exhibited high charge capacities more than 1100 mAh g^?1 and discharge capacities more than 700 mAh g^?1 at the first cycle. The SnO-B₂O₃ milled glasses proved to work as anode materials for rechargeable lithium batteries.     

锂电池负极材料氧化锡多孔疏松纳米球的制备、表征及电化学性能研究

在不使用模板和表面活性剂的前提下,利用水热法成功制备出了具有多孔疏松结构的SnO2纳米球,该球体是由无数个小的纳米颗粒组装而成的。运用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和选区电子衍射(SAED)等对所得产物的晶体结构和形貌进行了表征,同时也对其作为锂离子电池负极的电化学性能进行了系统的研究。     

Synthesis and electrochemical characterization of Si-Mn alloy anode materials for high energy lithium secondary batteries

The Si-Mn alloys as anode active materials were prepared by mechanical milling and calcination at three different temperatures like 600, 700, and 800 degrees C. The alloys were characterized by X-ray diffraction, field emission-scanning electron microscopy, field emission-transmission electron microscopy, and electrochemical cycling within a range of 2.5 V to 0.01 V versus Li/Li+. We found that the Si-Mn alloy calcined at 800 degrees C exhibited (i) an enhanced reversible capacity during the intercalation and de-intercalation process and (ii) a reduction in fading capacity characteristic due to modified structural and interfacial properties. Increasing the calcination temperature could improve the electrochemical performance of these materials, especially at 800 degrees C. Hence this alloy possibly suited to apply for lithium rechargeable batteries. The reversible capability after fourth cycling increases in the range of 95% to nearly 99% coulombic efficiency during the following intercalation and de-intercalation process. The Si-Mn alloy has the potential to be suitable for use as an anode active material in lithium rechargeable batteries.     

Synthesis and electrochemical characteristics of Sn-Sb-Ni alloy composite anode for Li-ion rechargeable batteries

Micro-scaled Sn-Sb-Ni alloy composite was synthesized from oxides of Sn, Sb and Ni via carbothermal reduction. The phase composition and electrochemical properties of the Sn-Sb-Ni alloy composite anode material were studied. The prepared alloy composite electrode exhibits a high specific capacity and a good cycling stability. The lithiation capacity was 530 mAh g⁻¹ in the first cycle and maintained at 370-380 mAh g⁻¹ in the following cycles. The good electrochemical performance may be attributed to its relatively large particle size and multi-phase characteristics. The former reason leads to the lower surface impurity and thus the lower initial capacity loss, while the latter results in a stepwise lithiation/delithiation behavior and a smooth volume change of electrode in cycles. The Sn-Sb-Ni alloy composite material shows a good candidate anode material for the rechargeable lithium ion batteries.     

Role of Mg dopant on the electrochemical performance of LiNi0.5Co0.5O2 cathode materials for lithium rechargeable batteries

Positive electrode materials, LiMg _x Ni_0.5−x Co_0.5O₂ (x = 0 < x < 0.5), have been successfully synthesized by microwave-assisted solution technique. The precursor has been analyzed by TG/DTA and the powder was calcined at 850 °C. The XRD patterns reveal that the synthesized materials exhibit hexagonal layered structure corresponding to space group. Coin cells of 2016 type have been fabricated using the synthesized layered material as cathode active material and lithium foil used as counter and reference electrode. Test cells were operated in the potential limits between 2.7 and 4.3 V using 1 M LiPF₆ in 1:1 EC/DEC as electrolyte. LiMg_0.2Ni_0.3Co_0.5O₂ material delivers an average discharge capacity of around 165 mA hg⁻¹ at 0.1 C rate over the investigated 20 cycles.     

尿素改性对钠离子电池负极材料NaTi_2(PO_4)_3电化学性能的影响

为提高水溶液钠离子电池负极材料NaTi_2(PO_4)_3(NTP)的导电性和倍率性能,以尿素(CO(NH_2)_2)为碳源采用溶剂热法合成了CO(NH_2)_2/NaTi_2(PO_4)_3(C/NTP)复合负极材料。采用XRD、SEM、TEM、Raman和恒流充放电等手段分析了材料的结构、C/NTP形貌和电化学性能。研究了不同阶段升温速率对C含量、包覆层石墨化程度及对电化学性能的影响。实验结果表明,低于400℃升温速率越小,C/NTP残碳量越高;400~650℃之间升温速率越小,包覆层石墨化程度越高,并提高了其电化学性能;在5C倍率下2℃/min热处理的样品首圈放电比容量为114.9mAh·g~(-1),循环30次后容量保持在91.9mAh·g~(-1);10C下放电比容量为87mAh·g~(-1),20C下放电比容量仍保持在71mAh·g~(-1),展现出高倍率下优异的循环性能。     

锂离子二次电池负极材料的研究综述

总结了在碳材料、合金材料和复合材料等3个锂离子电池负极材料研发的主导方向上的开发情况和它们各自特点,描述了目前的研究所面临难题,给出了锂离子电池负极材料研发取得重大突破的可能途径和建议.     

Pyrolitic carbon from biomass precursors as anode materials for lithium batteries

Disordered carbonaceous materials were synthesized by the pyrolysis of banana fibers treated with pore-forming substances such as ZnCl₂ and KOH. X-ray diffraction studies indicated a carbon structure with a large number of disorganized single layer carbon sheets. Addition of porogenic agent led to remarkable changes in the structure and morphology of the carbonaceous products. The product obtained with ZnCl₂ treatment gave first-cycle lithium insertion and de-insertion capacities of 3325 and 400 mAh g⁻¹, respectively. Lower capacities only could be realized in the subsequent cycles, although the coulombic efficiency increased upon cycling, which in the 10th cycle was 95%.     

Molten-salt decomposition synthesis of SnO2 nanoparticles as anode materials for lithium ion batteries

SnO₂ nanoparticles were synthesized by a simple, easily scaled-up molten-salt decomposition method with SnSO₄ as the molten salt and the reactive phase. During the synthesis process, the undecomposed molten SnSO₄ makes it possible to obtain SnO₂ nanoparticles by serving as the dispersion medium and keeping the particles from aggregation. The as-prepared SnO₂ had a tetragonal rutile structure with an average particle size of 50 nm. When used as anode materials for lithium ion battery, SnO₂ nanoparticles retained the charge capacity still as high as 402 mAh g^? 1 at a current density of 156 mA g^? 1 after 40 cycles. Moreover, cyclic voltammograms tests showed the formation/deformation of Li₂O was partially reversible.     

Electrochemical behavior of alpha-MoO3 nanorods as cathode materials for rechargeable lithium batteries

The electrochemical properties of alpha-MoO3 nanorods, which were synthesized via a solution-based method and following calcination, have been reported as a cathode material for rechargeable lithium batteries. Detailed lithium-insertion process of the material has been conducted by means of cyclic voltammetry, galvanostatic method, and impedance technique, and superior features associated with the nanostructures have been observed. The alpha-MoO3 nanorods exhibited an initial discharge capacity of 271.8 mAh/g under a current density of 0.1 mA/cm2 in the range 1.0 approximately 3.0 V, which nearly approached the theoretical capacity 280 mAh/g. Comparison of the structural and electrochemical characteristics with those of bulk alpha-MoO3 suggests the enhanced electrochemical performance might be related to the rodlike structure and increased edge and corner effects.     

3DOM SnO2-SiO2锂离子电池负极材料的制备及电化学性能

针对SnO2锂离子电池负极材料长循环性能差的缺点,把非晶SiO2引入SnO2材料中,形成SnO2-SiO2纳米复合材料。采用聚苯乙烯(PS)胶晶作为模板,制备出三维有序大孔SnO2-SiO2纳米复合材料。研究结果表明,3DOM SnO2材料晶体结构和3DOM SnO2-SiO2材料相似,但是加入SiO2以后,3DOM SnO2-SiO2材料的长循环性能得到显著提高。在500 mAh/g的电流密度下循环100次,此时加0%Si的3DOM SnO2-SiO2材料的充电比容量急剧衰减为147 mAh/g,加5%Si的3DOM SnO2-SiO2材料的充电比容量达654 mAh/g,此外500次循环后加5%Si的3DOM SnO2-SiO2材料充电比容量增至728 mAh/g。这些结果表明SiO2能够改善3DOM SnO2材料长循环稳定性。     

Nitrogen-containing carbons prepared from polyaniline as anode materials for lithium secondary batteries

Nitrogen-containing carbons have been prepared from polyaniline by carbonization and activation. Lithium storage performances of the carbons have been studied by galvanostatic charge/discharge. The carbon without activation shows a first discharge capacity of 729 mAh g^− 1, after activation, the capacity improved. The first discharge capacity of the carbon prepared by H₃PO₄ activation is 1083 mAh g^− 1, and that of the carbon prepared by KOH activation is as high as 2201 mAh g^− 1, whose reversible capacity is 1027 mAh g^− 1. To the carbon prepared by KOH activation, the first coulombic efficiency is just 47%, however, from the second cycle, the coulombic efficiency goes up rapidly to above 90%, the reversible capacity is still as high as 747 mAh g^− 1 after 20 cycles. It may be a promising candidate as an anode material for lithium secondary batteries.     

Dispersed materials for rechargeable lithium batteries: Reactive and non-reactive grinding

Reactive and non-reactive grinding has been used to prepare high dispersed lithium-transition metal cathode materials (LiMn₂O₄, LiCoO₂, LiV₃O₈, Li₃Fe₂(PO₄)₃, LiTi₂(PO₄)₃) and inorganic solid state Li-ion electrolytes (Li_1.3Al_0.3Ti_1.7(PO₄)₃) for rechargeable lithium batteries. Submicron particle size and the presence of cationic vacancies and cationic disordering positively influence electrochemical properties of as prepared cathodes, leading to larger practical capacity and stability upon intercalation-deintercalation of lithium ions. However, the advantages are observed only when the first electrochemical step is an insertion of Li⁺ ions (Li battery discharge). The conductivity of the Li_1.3Al_0.3Ti_1.7(PO₄)₃ lithium ion electrolyte prepared by using MA was of 2-3 order of magnitude higher than that for nonactivated sample owing to the absence of non-conductive impurities and lower grain boundary resistance.     

Crystalline polycyclic quinone derivatives as organic positive-electrode materials for use in rechargeable lithium batteries

The performance of 9,10-anthraquinone (AQ), and 5,7,12,14-pentacenetetrone (PT) as active materials for rechargeable lithium batteries was investigated. Positive-electrodes in which AQ and PT were incorporated showed initial discharge capacities of greater than 200 mAh/g_{(AQ or PT)}. The obtained discharge capacities suggest that a multi-electron redox reaction takes place in each derivative. The discharge capacity of the positive-electrode with AQ rapidly decreased during the charge/discharge cycles; however, the positive-electrode with PT showed a relatively good cycle-life performance; it maintained about 80% of the initial capacity even after 100 cycles.     

Graphene sheets decorated with ZnO nanoparticles as anode materials for lithium ion batteries

ZnO/graphene composites were synthesized using a facile solution-based method. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, and Raman spectra revealed that ZnO nanoparticles with a particle size of around 4 nm were densely and homogeneously deposited on graphene sheets. As the anode material for the lithium ion batteries, the ZnO/graphene composites delivered a stable capacity of 404 mAh/g after 100 cycles at a current rate of 0.5 C, which is much superior to bare ZnO nanoparticles. The battery performance result indicates the presence of graphene sheets in the composites effectively enhance the conductivity and accommodate the volume change.