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。     

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.     

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.     

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 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%.     

Ni（OH）2 particles synthesized by high energy ball milling

1 Introduction Ni(OH)2/NiOOH has been used as positive materials in alkaline secondary batteries for more than 100 years[1- 3]. The performance improvement of Ni(OH)2/NiOOH electrode is crucial for the application of these batteries as they are all positi…     

Enhanced cycling stability of La modified LiNi0.8–xCo0.1Mn0.1LaxO2 for Li-ion battery

A series of layered LiNi_0.8–xCo_0.1Mn_0.1La_xO₂ (x=0, 0.01, 0.03) cathode materials were synthesized by combining co-precipitation and high temperature solid state reaction to investigate the effect of La-doping on LiNi_0.8Co_0.1Mn_0.1O₂. A new phase La₂Li_0.5Co_0.5O₄ was observed by XRD, and the content of the new phase could be determined by Retiveld refinement and calculation. The cycle stability of the material is obviously increased from 74.3% to 95.2% after La-doping, while the initial capacity exhibits a decline trend from 202 mA·h/g to 192 mA·h/g. The enhanced cycle stability comes from both of the decrease of impurity and the protection of newly formed La₂Li_0.5Co_0.5O₄, which prevents the electrolytic corrosion to the active material. The CV measurement confirms that La-doped material exhibits better reversibility compared with the pristine material.     

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.     

模拟废旧锂离子电池湿法冶金浸出液再生铝掺杂LiNi0.5Co0.2Mn0.3O2正极材料

采用共沉淀法制备均相Al掺杂的LiNi0.5Co0.2Mn0.3O2正极材料,以利用Al对再生镍钴锰(NCM)正极材料的正面改性作用,并改善锂离子电池回收过程中繁琐和高成本的除杂过程.当浸出液中的Al3+含量为过渡金属(Ni、Co和Mn)总量的1％(摩尔分数)时,制备的Al掺杂NCM正极材料中晶格氧和Ni2+的浓度增加...     

Mg-Co复合掺杂对LiFePO4电化学性能的影响（英文）

通过固相反应制备了Mg2+和Co4+复合掺杂的LiFePO4电极材料。采用X射线衍射、恒电流充放电和循环伏安研究复合掺杂对 LiFePO4结构和电化学性能的影响。结果表明:复合掺杂能够提高 LiFePO4的首次放电比容量,0.1C和1C的放电容量分别达到147.2mA·h/g 和133.3mA·h/g。循环伏安测试结果表明:复合掺杂改善了LiFePO4的导电性能,增强了Li+的脱嵌可逆性。     

Electrochemical behavior of Li+, Mg2+, Na+ and K+ in LiFePO4/ FePO4 structures

Besides Li⁺ and Mg²⁺, the electrochemical behavior of Na⁺ and K⁺ in LiFePO₄/ FePO₄ structures was studied since they naturally coexist with Li⁺ and Mg²⁺ in brine. The cyclic voltammogram (CV) results indicated that Na⁺ exhibits some reversibility in LiFePO₄/FePO₄ structures. Its reduction peak appears at ?0.511 V, more negative than that of Li⁺ (?0.197 V), meaning that a relatively positive potential is beneficial for decreasing Na⁺ insertion. The reduction peak of K⁺ could not be found clearly, indicating that K⁺ is difficult to insert into the FePO₄ structure. Furthermore, technical experiments using real brine with a super high Mg/Li ratio (493) at a cell voltage of 0.7V showed that the final extracted capacity of Li⁺, Mg²⁺ and Na⁺ that can be attained in 1 g LiFePO₄ is 24.1 mg, 7.32 mg and 4.61 mg, respectively. The Mg/Li ratio can be reduced to 0.30 from 493, and the Na/Li ratio to 0.19 from 16.7, which proves that, even in super high Mg/Li ratio brine, if a cell voltage is appropriately controlled, it is possible to separate Li⁺ and other impurities effectively.     

锂离子电池用LiVPO4F/C基正极材料的制备和性能（英文）

将H2C2O4·2H2O,NH4H2PO4,NH4VO3和LiF通过球磨反应、烧结,合成了LiVPO4F/C基正极材料。在这个过程中,草酸起还原剂和碳源的作用,利用热重、X射线衍射、扫描电镜、透射电镜和碳-硫分析等手段对合成的前驱体和材料进行检测和分析。XRD分析表明,球磨反应后所得到的前驱体为无定形态,而烧结后的材料中除了LiVPO4F的衍射峰外,还存在Li3V2(PO4)3和V2O3衍射峰。材料颗粒均匀,尺寸约2μm。透射电镜分析表明,合成的材料颗粒表面包裹着一层约2nm厚的无定形碳。在截止电压3.0～4.4V时,合成的材料在0.1C和10C倍率下的放电比容量分别为151.3和102.5mA·h/g。在10C倍率下循环50次后容量保持率为90.4%。在LiVPO4F和Li3V2(PO4)3的循环伏安曲线中可以明显看到V3+/V4+的氧化还原峰。     

Improving electrochemical performance of Ni-rich layered oxide cathodes via one-step dual modification strategy

A one-step overall strategy from surface to bulk was proposed to simultaneously synthesize the Nb-doped and LiNbO₃-coated LiNi_0.83Co_0.12Mn_0.05O₂ cathode materials. The incorporation of LiNbO₃ coating can regulate the interface and facilitate the diffusion of Li-ions. Simultaneously, the stronger Nb—O bond can effectively suppress Li⁺/Ni²⁺ cation mixing and strengthen the stability of crystal structure, which helps to mitigate the anisotropic variations of lattice parameters during Li⁺ de/intercalation. The results showed that the dual-modified materials exhibited good structural stability and distinguished electrochemical performance. The optimal NCM-Nb2 sample showed an excellent capacity retention of 90.78% after 100 cycles at 1C rate between 2.7 and 4.3 V, while only 67.90% for the pristine one. Meanwhile, it displayed a superior rate capability of 149.1 mA·h/g at the 10C rate. These results highlight the feasibility of one-step dual modification strategy to synchronously improve the electrochemical performance of Ni-rich layered oxide cathodes.     

Influence of pH value and chelating reagent on performance of Li3V2(PO4)3/C cathode material

The Li₃V₂(PO₄)₃/C composite cathode material was synthesized via sol-gel method using three different chelating agents (citric acid, salicylic acid and polyacrylic acid) at pH value of 3 or 7. The crystal structure, morphology, specific surface area and electrochemical performance of the prepared samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge test. The results show that the effects of pH value on the performance of the prepared materials are greatly related to the chelating agents. With salicylic acid or polyacrylic acid as the chelating reagent, the structure, morphology and electrochemical performance of the samples are greatly influenced by the pH values. However, the structure of the materials with citric acid as the chelating agent does not change as pH value changes, and the materials own uniform particle size distribution and good electrochemical performance. It delivers an initial discharge capacity of 113.58 mA·h/g at 10C, remaining as high as 108.48 mA·h/g after 900 cycles, with a capacity retention of 95.51%.     

Influence of Ti^4＋ doping on electrochemical properties of LiFePO4/C cathode material for lithium-ion batteries

To improve the performance of LiFePO4, single phase Li1-4xTixFePO4/C (x=0, 0.005, 0.010, 0.015) cathodes were synthesized by solid-state method. A certain content of glucose was used as carbon precursor and content of carbon in every final product was about 3.5%. The samples were characterized by X-ray diffraction(XRD), scanning electron microscopy observations(SEM), charge/discharge test, carbon analysis and electrochemical impedance spectroscopy(EIS). The results indicate that the prepared samples have ordered olivine structure and doping of the low concentration Ti~(4+) does not affect the structure of the samples. The electrochemical capabilities evaluated by charge-discharge test show that the sample with 1% Ti~(4+) (molar fraction) has good electrochemical performance delivering about an initial specific capacity of 146.7 mA·h/g at 0.3C rate. Electrochemical impedance spectroscopy measurement results show that the charge transfer resistance of the sample could be decreased greatly by doping an appropriate amount Ti~(4+).     

Enhanced cycling stability of Mg–F co-modified LiNi0.6Co0.2Mn0.2–yMgyO2–zFz for lithium-ion batteries

The layered LiNi_0.6Co_0.2Mn_0.2–yMg_yO_2–zF_z (0≤y≤0.12, 0≤z≤0.08) cathode materials were synthesized by combining co-precipitation method and high temperature solid-state reaction, with the help of the ball milling, to investigate the effects of F–Mg doping on LiNi_0.6Co_0.2Mn_0.2O₂. Compared with previous studies, this doping treatment provides substantially improved electrochemical performance in terms of initial coulombic efficiency and cycle performance. The LiNi_0.6Co_0.2Mn_0.11Mg_0.09O_1.96F_0.04 electrode delivers an high capacity retention of 98.6% during the first cycle and a discharge capacity of 189.7 mA·h/g (2.8–4.4 V at 0.2C), with the capacity retention of 96.3% after 100 cycles. And electrochemical impedance spectroscopy(EIS) results show that Mg–F co-doping decreases the charge-transfer resistance and enhances the reaction kinetics, which is considered to be the major factor for higher rate performance. It is demonstrated that LiNi_0.6Co_0.2Mn_0.11Mg_0.09O_1.96F_0.04 is a promising cathode material for lithium-ion batteries for excellent electrochemical properties.     

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F锂离子电池正极材料Li1.03Co0.10Mn1.90FzO4-z的制备及电化学性能

以Li2CO3、Mn2O3、Co2O3及LiF为原料,采用高温固相法合成了掺F的Li1.03Co0.10Mn1.90FzO4?z锂电池正极材料。通过离子发射光谱(ICP)和电位分析法确定了材料的化学组成,用X-射线衍射(XRD)、扫描电子显微镜(SEM)和电化学测试仪分析了 F 掺杂量对材料结构、形貌和电池性能的影响。结果表明,掺 F 的Li1.03Co0.10Mn1.90FzO4?z正极材料为尖晶石结构,在F掺入量z≤0.10时,随着掺杂量的增加晶胞参数逐渐增加,当F掺杂量继续增加时,晶胞参数的增幅有所减小。适量的F?与金属离子Li+、Co+的复合掺杂提高了材料的放电比容量,同时增强了材料结构的稳定性。电化学性能测试表明,Li1.03Co0.10Mn1.90F0.15O3.85的首次放电比容量达到111.0 mA·h/g,0.2C倍率下30次循环后容量保持率为97.0%。     

Facile fabrication of spherical flower-like Mg(OH)2 and its fast and efficient removal for heavy metal ions

Spherical flower-like Mg(OH)₂ was fabricated from MgSO₄ effluent and its adsorption performance for heavy metal ions was evaluated. The appropriate fabrication conditions are as follows: Mg²⁺/NH₄OH molar ratio of 1:0.5, temperature of 120 °C and time of 1 h at Mg²⁺ concentration of 2 mol/L. Spherical flower-like Mg(OH)₂ composed of ultra-thin sheets exhibits an excellent adsorption ability for Ni²⁺, Cu²⁺, Zn²⁺, Pb²⁺, Fe³⁺ and Co²⁺, and the adsorption reaches the equilibrium in 6 min. The maximum adsorption capacities of the studied heavy metal ions onto Mg(OH)₂ at 20 °C are 58.55, 85.84, 44.94, 485.44, 625.00 and 27.86 mg/g, respectively. The adsorption is well fitted by the Langmuir model, indicating that the adsorption is monolayer. The adsorption kinetics follows the pseudo-second- order model. Chemisorption is the operative mechanism. Spherical flower-like Mg(OH)₂ is a qualified candidate for heavy metal ions removal.     

Effect of lithium content on electrochemical property of Li1+x(Mn0.6Ni0.2Co0.2)1-xO2 (0≤x≤0.3) composite cathode materials for rechargeable lithium-ion batteries

In order to confirm the optimal Li content of Li-rich Mn-based cathode materials (a fixed mole ratio of Mn to Ni to Co is 0.6:0.2:0.2), Li_1+x(Mn_0.6Ni_0.2Co_0.2)_1-xO₂ (x=0, 0.1, 0.2, 0.3) composites were obtained, which had a typical layered structure with and C2/m space group observed from X-ray powder diffraction (XRD). Electron microscopy micrograph (SEM) reveals that the particle sizes in the range of 0.4-1.1 μm increase with an increase of x value. Li_1.2(Mn_0.6Ni_0.2Co_0.2)_0.8O₂ sample delivers a larger initial discharge capacity of 275.7 mA·h/g at the current density of 20 mA/g in the potential range of 2.0–4.8 V, while Li_1.1(Mn_0.6Ni_0.2Co_0.2)_0.9O₂ shows a better cycle performance with a capacity retention of 93.8% at 0.2C after 50 cycles, showing better reaction kinetics of lithium ion insertion and extraction.