Synthesis of LiNi1/3CO1/3Mn1/3O2 cathode material via oxalate precursor

Using oxalic acid and stoichiometrically mixed solution of NiCl2, CoCl2, and MnCl2 as starting materials, the triple oxalate precursor of nickel, cobalt, and manganese was synthesized by liquid-phase co-precipitation method. And then the LiNi1/3Co1/3Mn1/3O2 cathode materials for Li-ion battery were prepared from the precursor and LiOH-H2O by solid-state reaction. The precursor and LiNi1/3Co1/3Mn1/3O2 were characterized by chemical analysis, XRD, EDX, SEM and TG-DTA. The results show that the composition of precursor is Ni1/3Co1/3Mn1/3C2O4·2H2O. The product LiNi1/3Co1/3Mn1/3O2, in which nickel, cobalt and manganese are uniformly distributed, is well crystallized with a-NaFeO2 layered structure. Sintering temperature has a remarkable influence on the electrochemical performance of obtained samples. LiNi1/3Co1/3Mn1/3O2 synthesized at 900 ℃ has the best electrochemical properties. At 0.1C rate, its first specific discharge capacity is 159.7 mA·h/g in the voltage range of 2.75-4.30 V and 196.9 mA·h/g in the voltage range of 2.75-4.50 V; at 2C rate, its specific discharge capacity is 121.8 mA·h/g and still 119.7 mA·h/g after 40 cycles. The capacity retention ratio is 98.27%.     

Cu单掺杂和Cu/Al复合掺杂纳米氢氧化镍的结构和电化学性能(英文)

采用超声波辅助沉淀法制备Cu单掺杂和Cu/Al复合掺杂的纳米Ni(OH)2样品,测试样品的晶相结构、粒径、形貌、振实密度及电化学性能。结果表明,样品均具有α相结构且其平均粒度的分布范围窄,Cu单掺杂的纳米Ni(OH)2呈现不规则形态,而Cu/Al复合掺杂的纳米Ni(OH)2呈准球状且具有更大的振实密度。将纳米样品以8%的比例掺入到商业用微米级球形镍中制成混合电极。充放电和循环伏安测试结果表明,Cu/Al复合掺杂纳米Ni(OH)2的电化学性能优于Cu单掺杂的纳米Ni(OH)2的,前者的放电比容量最高达到330mA·h/g(0.2C),比Cu单掺杂样品的高12mA·h/g,比纯球镍电极的高91mA·h/g。此外,Cu/Al复合掺杂纳米样品的质子扩散系数比Cu单掺杂样品的高52.3%。     

Synthesis and electrochemical performances of LiNi0.6Co0.2Mn0.2O2 cathode materials

LiNi_0.6Co_0.2Mn_0.2O₂ was prepared from LiOH·H₂O and MCO₃ (M=Ni, Co, Mn) by co-precipitation and subsequent heating. XRD, SEM and electrochemical measurements were used to examine the structure, morphology and electrochemical characteristics, respectively. LiNi_0.6Co_0.2Mn_0.2O₂ samples show excellent electrochemical performances. The optimum sintering temperature and sintering time are 850 °C and 20 h, respectively. The LiNi_0.6Co_0.2Mn_0.2O₂ shows the discharge capacity of 148 mA·h/g in the range of 3.0?4.3 V at the first cycle, and the discharge capacity remains 136 mA·h/g after 30 cycles. The carbonate co-precipitation method is suitable for the preparation of LiNi_0.6Co_0.2Mn_0.2O₂ cathode materials with good electrochemical performance for lithium ion batteries.     

Synthesis and behavior ofAl-stabilized α-Ni（OH）2

Nano-fibrous Al-stabilized α-Ni(OH)2 was synthesized by the urea thermal decomposition method. The grain morphology, crystal structure, thermal stability, chemical composition and electrochemical performance of the Al-stabilized α-Ni(OH)2 were investigated. It is found that the urea thermal decomposition is an appropriate way to precipitate the Al-stabilized α-Ni(OH)2 with excellent performance. The fiber cluster TEM pattern shows that the synthesized α-Ni(OH)2 powder is composed of agglomerates of much smaller primary particles. The stabilized α-Ni(OH)2 powder with a 7.67 A c-axis distance and low thermal stabilities is obtained. The FTIR spectrum shows that the materials contain absorbed water molecules, and intercalated CO32- and SO42- anions. The experimental α-Ni(OH)2 electrode exhibits excellent electrochemical redox reversibility, high special capacity, good rate discharging performance and perfect cyclic stability. Moreover, the synthesized α-Ni(OH)2 electrode also shows high discharge capacity and cyclic stability at high temperature. The electrode specific capacity remains 290 mA-h/g at 60 ℃, which is only 15 mA-h/g lower than its ambient value, and the capacity loss is 0.9 mA-h/g per charge-discharge cycle.     

Synthesis and electrochemical properties of Li[NixCoyMn1-x-y]O2 （x, y= 2/8, 3/8） cathode materials for lithium ion batteries

The uniform layered Li(Ni_2/8Co_3/8Mn_3/8)O₂, Li(Ni_3/8Co_2/8Mn_3/8)O₂, and Li(Ni_3/8Co_3/8Mn_2/8)O₂ cathode materials for lithium ion batteries were prepared using the hydroxide co-precipitation method. The effects of calcination temperature and transition metal contents on the structure and electrochemical properties of the Li-Ni-Co-Mn-O were systemically studied. The results of XRD and electrochemical performance measurement show that the ideal preparation conditions were to prepare the Li(Ni_3/8Co_3/8Mn_2/8)O₂ cathode material calcined at 900°C for 10 h. The well-ordered Li(Ni_3/8Co_3/8Mn_2/8)O₂ synthesized under the optimal conditions has the I ₀₀₃/I ₁₀₄ ratio of 1.25 and the R value of 0.48 and delivers the initial discharge capacity of 172.9 mA·h·g⁻¹, the discharge capacity of 166.2 mA·h·g⁻¹ after 20 cycles at 0.2C rate, and the impedance of 558 Ω after the first cycle. The decrease of Ni content results in the decrease of discharge capacity and the bad cycling performance of the Li-Ni-Co-Mn-O cathode materials, but the decreases of Mn content and Co content to a certain extent can improve the electrochemical properties of the Li-Ni-Co-Mn-O cathode materials.     

Influence of Y^3＋ doping on structure and electrochemical performance of layered Li1.05V3O8

LiOH.H2O,V2O5 and Y(NO3)3 were used as raw materials to synthesize the precursors containing Li,V and Y by liquid-state reaction,then the cathode materials Li1.05YxV3-xO8(x=0,0.002 5,0.005,0.01,0.02,0.1,0.2)for lithium-ion battery were obtained by calcining the precursors.The influence of Y3 doping on structure,conductivity and electrochemical performance of Li1.05V3O8 were investigated by using XRD,cyclic voltammograms,AC impedance,etc.The results show that Li1.05YxV3-xO8 with different doping amounts have well-developed crystal structure of layered Li1.05V3O8 and lengthened interlayer distance of(100) crystal plane.Y3 can insert into crystal lattice completely when the doping amount is small and the impurity phase of YVO4 is found when x≥0.1.There is no change in the process of Li insertion-deinsertion with Y 3 doping.The conductivity is clearly improved due to small amount of Y 3 doping and it tends to increase first and then decrease with increasing doping amount.The initial discharge capacity and plateau potential are both enhanced with proper amount of Y3 doping.When x is 0.005,the first specific discharge capacity reaches 288.9 mA.h/g,4.60%larger than that of undoped sample(276.2 mA.h/g).When x≤0.1,the average discharge plateau potentials are enhanced by about 0.15 V,which makes for higher energy density.     

掺铝氧化锌包覆LiFePO4的合成与性能（英文）

以简单的固相法合成了橄榄石结构LiFePO4,并以导电掺铝氧化锌材料(AZO)对其表面进行包覆。充放电结果显示,表面包覆大幅度改善了LiFePO4材料的倍率和低温性能。在20C高倍率条件下,AZO包覆LiFePO4的放电比容量可达100.9mA·h/g;在低温20°C时进行0.2C充放电,未包覆LiFePO4和AZO包覆LiFePO4的放电比容量分别为50.3mA·h/g和119.4mA·h/g。经分析,这可能是由于采用导电AZO包覆措施而增加了LiFePO4材料的电导率,从而极大地提高了其比容量。另外,导电AZO包覆措施还增加了LiFePO4材料的振实密度。这些结果表明AZO包覆LiFePO4材料是一种很好的适用于锂离子动力电池的正极材料。     

改进溶剂热法制备锂离子电池负极材料用多级孔Co3O4微球

将溶剂热法与高温煅烧法相结合制备多级孔Co3O4微球,采用XRD、SEM、TEM和电化学测试等技术研究该多级孔Co3O4微球的结构和性能.结果表明:当煅烧温度为700℃时,所合成的Co3O4(Co3O4-700)是由丰富的纳米颗粒(50～200 nm)和大量孔洞(～100 nm)构成的微米级微球(1～2μm);该Co3...     

Enhancing electrochemical performance of SnO2 anode with humic acid modification

Humic acid (HA) was studied as a modifier in the SnO₂ anode preparation for the electrochemical performance improvement. Scanning electron microscopy, 180° peel test, and nanoindentation experiment were used to examine the influence of the HA on electrode. The results showed that the addition of HA could improve the dispersion uniformity of all particles. The components were tightened, increasing the difficulty of peeling off the film from the current collector. The deformation resistance of the electrode was greatly enhanced by the HA modification. The electrochemical test results showed that the anode from the normal micron-sized SnO₂ particles with the HA modifier exhibited significant progress in electrochemical performance compared with those without HA. The reversible specific capacity of the SnO₂ anode can be maintained as high as 733.4 mA·h/g at a current density of 100 mA/g after 50 cycles. Therefore, HA is a promising modifier for anode preparation of lithium-ion batteries.     

Effect of Mg and Co co-doping on electrochemical properties of LiFePO4

LiFePO₄ co-doped with Mg²⁺ and Co⁴⁺ ions was synthesized by a solid state reaction method. The structure and electrochemical properties of the prepared LiFe_0.99Mg_0.005Co_0.005PO₄ were investigated by X-ray diffraction (XRD), galvanostatic charge-discharge experiment and cyclic voltammograms (CV). Specific discharge capacity of LiFePO₄ co-doped with Mg and Co ions reach 147.2 mA·h/g at 0.1C and 133.3 mA·h/g at 1C. The results of CV show that the reversibility of lithium extraction/insertion in LiFePO₄ can be promoted by (Mg²⁺, Co⁴⁺) multiple-ion doping.     

稀土金属离子掺杂对LiFePO4结构和性能的影响

采用稀土金属离子(Er3+、Y3+、Nd3+)分别对LiFePO4的Li、Fe原子位进行掺杂,通过X射线衍射(XRD)、恒电流充放电及电化学阻抗(EIS)法系统地研究掺杂对LiFePO4结构和性能的影响。结果表明:掺杂试样的微观结构和性能与掺杂离子半径、取代位置密切相关。LiFe0.99Y0.01PO4试样具有最佳的电化学性能,在15mA.g-1放电电流密度下首次放电容量达到149.8mAh.g-1,当电流密度增加到300mA.g-1时,放电容量为134.3mAh.g-1,经过50次循环充放电后,放电容量保持率为99.1%。     

A simple physical mixing method for MnO2/MnO nanocomposites with superior Zn2+ storage performance

MnO₂/MnO cathode material with superior Zn²⁺ storage performance is prepared through a simple physical mixing method. The MnO₂/MnO nanocomposite with a mixed mass ratio of 12:1 exhibits the highest specific capacity (364.2 mA·h/g at 0.2C), good cycle performance (170.4 mA·h/g after 100 cycles) and excellent rate performance (205.7 mA·h/g at 2C). Analysis of cyclic voltammetry (CV) data at various scan rates shows that both diffusion- controlled insertion behavior and surface capacitive behavior contribute to the Zn²⁺ storage performance of MnO₂/MnO cathodes. And the capacitive behavior contributes more at high discharge rates, due to the short paths of ion diffusion and the rapid transfer of electrons.     

Synthesis of porous nano/micro structured LiFePO4/C cathode materials for lithium-ion batteries by spray-drying method

In order to enhance electrochemical properties of LiFePO₄ (LFP) cathode materials, spherical porous nano/micro structured LFP/C cathode materials were synthesized by spray drying, followed by calcination. The results show that the spherical precursors with the sizes of 0.5–5 μm can be completely converted to LFP/C when the calcination temperature is higher than 500 °C. The LFP/C microspheres obtained at calcination temperature of 700 °C are composed of numerous particles with sizes of ～20 nm, and have well-developed interconnected pore structure and large specific surface area of 28.77 m²/g. The specific discharge capacities of the LFP/C obtained at 700 °C are 162.43, 154.35 and 144.03 mA·h/g at 0.5C, 1C and 2C, respectively. Meanwhile, the capacity retentions can reach up to 100% after 50 cycles. The improved electrochemical properties of the materials are ascribed to a small Li⁺ diffusion resistance and special structure of LFP/C microspheres.     

热处理对包含正二十面体准晶相Ti1.4V0.6Ni合金电极的电化学性能的影响（英文）

研究了热处理前后Ti1.4V0.6Ni合金的结构和电化学性能。采用X射线粉末衍射(XRD)方法分析合金的结构。电化学特性包括放电容量、循环稳定性和高倍率放电性能等。XRD衍射分析表明,在590°C热处理30min的合金,主要包含正二十面体准晶相、Ti2Ni(FCC)相、V基固溶相(BCC)和C14Laves相(Hex)。电化学测试显示,热处理后在30°C和放电电流密度为30mA/g的条件下,合金电极的最大放电容量可达330.9mA·h/g,并且循环稳定性和高倍率放电性能也得到改善。此外,通过电化学阻抗和合金内部氢的扩散系数研究了合金电极的动力学性能。     

介孔Li3V2（PO4）3正极材料的研磨溶胶凝胶法合成和电化学性能（英文）

以V2O5·nH2O、LiOH·H2O、NH4H2PO4和蔗糖为原料,采用研磨溶胶凝胶技术制备了无定形Li3V2(PO4)3前驱体,再经过焙烧获得具有单斜结构的介孔Li3V2(PO4)3正极材料,并用XRD、SEM、TEM、比表面积和电化学性能测试来表征材料的性能。研究表明,在700°C下焙烧的样品具有良好的介孔结构、最大的比表面积(188cm2/g)和最小的孔径(9.3nm)。在0.2C倍率下,该介孔样品的首次放电容量达155.9mA·h/g,经过50次循环后其容量仍然可达154mA·h/g,表现出非常稳定的放电性能。     

Preparation and electrochemical properties of LiFePO4/C composite with network structure for lithium ion batteries

The bare LiFePO4 and LiFePO4/C composites with network structure were prepared by solid-state reaction. The crystalline structures, morphologies and specific surface areas of the materials were investigated by X-ray diffractometry（XRD）, scanning electron microscopy（SEM） and multi-point brunauer emmett and teller（BET） method. The results show that the LiFePO4/C composite with the best network structure is obtained by adding 10% phenolic resin carbon. Its electronic conductivity increases to 2.86 × 10^-2 S/cm. It possesses the highest specific surface area of 115.65 m^2/g, which exhibits the highest discharge specific capacity of 164.33 mA.h/g at C/IO rate and 149.12 mA.h/g at 1 C rate. The discharge capacity is completely recovered when C/10 rate is applied again.     

Improvement of electrochemical and electrical properties of LiFePO<Subscript>4</Subscript> coated with citric acid

LiFePO₄ was synthesized using hydrothermal method and coated with different amounts of citric acid as carbon source.The samples were characterized by X-ray powder diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscope（TEM）,surface area measurement—Brunauer–Emmett–Teller（BET）,discharge capability,cyclic voltammetry（CV）,and electrochemical impedance spectroscopy（EIS）.The results show that the quality and thickness of the carbon coating on the surface of LiFePO₄ particles are very important.The optimum carbon content（about 30 wt%）can lead to a more uniform carbon distribution.Electrochemical results show that the samples containing 20 wt%,30 wt%,40 wt%,and50 wt% carbon deliver a discharge capacity of 105,167,151,and 112 mAhg^-1,respectively,at the rate of 0.1C.The increase of carbon content leads to the decrease of discharge capacity of LiFePO₄/C,owing to the fact that excess carbon delays the diffusion of Li⁺ through the carbon layers during charge/discharge procedure.The LiFePO₄/C with low carbon content exhibits poor electrochemical performance because of its low electrical conductivity.Therefore,the amount of carbon must be optimized in order to achieve excellent electrochemical performance of LiFePO₄/C for its application in a lithium ion battery.     

Facile synthesis of high capacity P2-type Na2/3Fe1/2Mn1/2O2 cathode material for sodium-ion batteries

P2-type Na_2/3Fe_1/2Mn_1/2O₂ was synthesized by a facile sol−gel method, and the effect of calcination temperature on the structure, morphology and electrochemical performance of samples was investigated. The results show that the sample obtained at 900 °C is pure P2-type Na_2/3Fe_1/2Mn_1/2O₂ phase with good crystallization, which consists of hexagon plate-shaped particles with the size and thickness of 2−4 µm and 200−400 nm, respectively. The sample exhibits an initial specific discharge capacity of 243 mA·h/g at a current density of 26 mA/g with good cycling stability. The high specific capacity indicates that P2-type Na_2/3Fe_1/2Mn_1/2O₂ is a promising cathode material for sodium- ion batteries.     

Ni2+替代对LiFePO4正极材料电化学性能的影响

利用炭热还原法合成了橄榄石型LiFe1-xNixPO4/C (x=0.0,0.1,0.3,0.5) 正极材料,并系统研究了Ni2+替代对材料电化学性能的影响。充放电循环、循环伏安和交流阻抗测试,结果表明Ni2+替代部分Fe2+可以显著改善LiFePO4材料的电化学性能。在0.2 C (1 C=170.0 mA·g-1)电流密度下,LiFe0.9Ni0.1PO4/C的放电比容量达到160 mAh·g-1。LiFe1-xNixPO4/C电化学性能的改善归因于材料电导率的提高和电荷传输电阻的降低。利用第一性原理对LiFe1-xNixPO4/C的电子结构进行了研究,结果表明Ni2+的铁位替代能够提高体系的电子电导性。LiFe0.875Ni0.125PO4的结构最稳定,带隙最小,导电性能最好     

Sb2S3 nanorods/porous-carbon composite from natural stibnite ore as high-performance anode for lithium-ion batteries

To avoid the high purity reagents and high energy consumption involved in the manufacturing of lithium-ion battery anode materials, Sb₂S₃ nanorods/porous-carbon anode was prepared by remodeling natural stibnite ore with porous carbon matrix via a simple melting method. Due to the nanostructure of Sb₂S₃ nanorods and synergistic effect of porous carbon, the Sb₂S₃ nanorods/porous-carbon anode achieved high cyclic performance of 530.3 mA·h/g at a current density of 100 mA/g after 150 cycles, and exhibited a reversible capacity of 130.6 mA·h/g at a high current density of 5000 mA/g for 320 cycles. This shows a great possibility of utilizing Sb₂S₃ ore as raw material to fabricate promising anodes for advanced lithium-ion batteries.