The cathode material LiNi0. 8Co0. 2O2 was synthesized by co-precipitation using urea. The influence of different methods and synthesis conditions on the physical and electrochemical performance of LiNi0. 8Co0. 2Mn0. 2O2 was analyzed,and the synthesis conditions were optimized. The optimum conditions of synthesis LiNi0. 8Co0. 2O2 were sintered at 800 ℃ for 10 h,and the electrochemical performance of the sample was excellent. Its first charge and discharge capacity was 206. 4 mAh·g- 1and 191. 6 mAh·g- 1,the capacity retained 178.2 mAh·g- 1after 30 cycles.

Li3V2(PO4)(3)/C samples were synthesized by two different synthesis methods. Their influence on electrochemical performances of Li3V2(PO4)(3)/C as cathode materials for lithium-ion batteries was investigated. The structure and morphology of Li3V2(PO4)(3)/C samples were characterized by X-ray diffraction and scanning electron microscopy. Electrochemical performance was characterized by charge/discharge, cyclic voltammetry, and alternating current (AC) impedance measurements. Li3V2(PO4)(3)/C with smaller grain size showed better performances in terms of the discharge capacity and cycle stability. The improved electrochemical properties of the Li3V2(PO4)(3)/C were attributed to the decreasing grain size and enhanced electrical conductivity produced via low temperature route. AC impedance measurements also showed that the Li3V2(PO4)(3)/C synthesized by low temperature route significantly decreased the charge-transfer resistance and shortened the migration distance of lithium ion.

The cathode material LiNi1/3Co1/3Mn1/3O2 for lithium ion battery is prepared by the hydroxide co-precipitation method.X-ray diffraction(XRD),scanning electron microscopy(SEM) and electrochemical tests are used to characterize the structure,appearance and electrochemical performance of LiNi1/3Co1/3Mn1/3O2. It is found that the sample synthesized at 800℃ for 12h has homogenous distribution of particles. The electrochemical test shows that the initial discharge capacity of LiNi1/3Co1/3Mn1/3O2 powder is 150mAh·g-1 at the rate of 0.2C,and the capacity retains 137mAh·g-1 after 30 cycles.

以氢氧化物共沉淀法合成了Ni0.4Co0.2Mn0.4(OH)2前驱体,然后以Ni0.4Co0.2Mn0.4(OH)2和LiOH为原料,合成出了层状结构的锂离子电池正极材料LiNi0.4Co0.2Mn0.4O2.通过XRD、SEM和电化学测试对LiNi0.4Co0.2Mn0.4O2材料的结构、形貌及电化学性能进行了测试和表征.结果表明,800℃烧结12h合成的样品粒度大小分布比较均匀,以0.2C充放电,其首次放电容量为148mAh·g-1,循环30次后容量为136mAh·g-1.

The structures of LiNi1/3Co1/3Mn1/3O2 were presented.Preparation methods and improvement of LiNi1/3Co1/3Mn1/3O2 with their merits and defects were reviewed and their prospect applications were given.

Triclinic LiVPO4F/C composite materials were prepared from a sucrose-containing precursor by one-step heat treatment. As-prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements. XRD studies showed that Li3PO4 impurity phase appeared in the sample synthesized at 600°C and pure LiVPO4F samples could be obtained when the sintered temperature was higher than 650°C. The sample synthesized at 650°C presents the highest initial discharge capacity of 132mAhg−1 at 0.2 C rate, and exhibited better cycling stability (124mAhg−1 at 50th cycle at 0.2 C rate) and better rate capability (100mAhg−1 at 50th cycle under 1 C rate) in the voltage range 3.0–4.4V.

The cathode material Li Ni0.4Co0.2Mn0.4O2 for lithium ion battery was prepared by hydroxide co-precipitation method.X-ray diffraction(XRD),scanning electron microscopy(SEM) and electrochemical tests were used to characterize structure,appearance and electrochemical performances of Li Ni0.4Co0.2Mn0.4O2.It was found that the sample synthesized at 800℃ for 12h was homogenous distribution of particles.Electrochemical test showed that the initial discharge capacity of Li Ni0.4Co0.2Mn0.4O2 powder was 148mAh·g-1 at the rate of 0.2C,and the capacity retained 136mAh·g-1 after 30cycles.

Li 3 V 2 (PO 4 ) 3 /C samples were synthesized by two different synthesis methods. Their influence on electrochemical performances of Li 3 V 2 (PO 4 ) 3 /C as cathode materials for lithium-ion batteries was investigated. The structure and morphology of Li 3 V 2 (PO 4 ) 3 /C samples were characterized by X-ray diffraction and scanning electron microscopy. Electrochemical performance was characterized by charge/discharge, cyclic voltammetry, and alternating current (AC) impedance measurements. Li 3 V 2 (PO 4 ) 3 /C with smaller grain size showed better performances in terms of the discharge capacity and cycle stability. The improved electrochemical properties of the Li 3 V 2 (PO 4 ) 3 /C were attributed to the decreasing grain size and enhanced electrical conductivity produced via low temperature route. AC impedance measurements also showed that the Li 3 V 2 (PO 4 ) 3 /C synthesized by low temperature route significantly decreased the charge-transfer resistance and shortened the migration distance of lithium ion.

Y-doped Li3V2(PO4)3 cathode materials were prepared by a carbothermal reduction(CTR) process. The properties of the Y-doped Li3V2(PO4)3 were investigated by X-ray diffraction (XRD) and electrochemical measurements. XRD studies showed that the Y-doped Li3V2(PO4)3 had the same monoclinic structure as the undoped Li3V2(PO4)3. The Y-doped Li3V2(PO4)3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram (CV), and electrochemical impedance spectra (EIS). The optimal doping content of Y was x=0.03 in Li3V2–xYx(PO4)3 system. The Y-doped Li3V2(PO4)3 samples showed a better cyclic ability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Y-doping. The improved electrochemical performances of the Y-doped Li3V2(PO4)3 cathode materials were attributed to the addition of Y3+ ion by stabilizing the monoclinic structure.

采用氢氧化物共沉淀法合成了Ni1／3Co1／3Mn1/3（OH）2前驱体，然后以Ni1／3Co1／3Mn1／3（OH）2和LiOH·H2O为原料，合成出了层状锂离子电池正极材料LiNi1／3Co1/3Mn1／3O2。通过XRD、SEM和电化学测试对LiNi1／3-Co1/3Mn1/3O2材料的结构、形貌及电化学性能进行了测试和表征。结果表明，800℃烧结12h所合成的样品粒度大小分布比较均匀，该材料以0．2C充放电，其首次放电容量为150mAh·g^-1，循环30次后容量为137mAh·g^-1。

The effect of fluorine substitution on the electrochemical properties of Li3V2(PO4)(3) cathode materials was studied. Samples with stoichiometric proportions of Li3V2(PO4)(3-x)F-x (x = 0, 0.05, 0.10, 0.15) were prepared by adding LiF in the starting materials of Li3V2(PO4)(3). XRD studies showed that the F-substituted Li3V2(PO4)(3) had the same monoclinic structure as the un-substituted Li3V2(PO4)(3). SEM images showed that F-substitution Li3V2(PO4)(3) had a regular and uniform particles. The results of electrochemical measurement showed that F-substitution can improve the rate capability of these cathode materials. The Li3V2(PO4)(2.90)F-0.10 sample showed the best high rate performance. Its discharge capacity at 10 C rate was 117 mA h g(-1) with 30th capacity retention of about 90.60%. The electrode reaction reversibility and electronic conductivity was enhanced, and the charge transfer resistance was decreased through F-substitution. The improved electrochemical performance of F-substitution Li3V2(PO4)(3) cathode materials were attributed to the above factors. (C) 2009 Elsevier Ltd. All rights reserved.

LiVPO4F/C cathode material was synthesized by a novel one-step solid-state reaction method using humic acid as both reduction agent and carbon sources. The SEM image showed that the particles merged with each other to form a porous structure. Electrochemical test showed that the initial discharge capacity of LiVPO4F/C powder was 139 mA h g(-1) and the capacity was 132 mA h g(-1) after 30 cycles.

The cathode material LiNi0.4Co0.2Mn0.4O2 for lithium ion battery was prepared by carbonate co-precipitation method.X-ray diffraction(XRD),scanning electron microscopy(SEM) and electrochemical tests were used to characterize structure,appearance and electrochemical performances of LiNi0.4Co0.2Mn0.4O2.It was found that the sample synthesized at 800 ℃ for 12 h is homogenous distribution of particles.Electrochemical test shows that the initial discharge capacity of LiNi0.4Co0.2Mn0.4O2 powder is 151 mAh·g-1 at the rate of 0.2 C,and the capacity retains 138 mAh·g-1 after 30 cycles.

介绍了锂离子电池正极材料Li3V2(PO4)3和LiVPO4F的结构和电化学性质;综述了Li3V2(PO4)3和LiV-PO4F的制备方法及其优缺点,并对它们的应用前景进行了展望.