共沉淀法制备LaF3表面修饰LiNi1／3C01／3Mn1／302及性能研究

以LiNi1／3CO1／3Mn1／302为正极材料,采用共沉淀合成方法制备LaF3表面修饰LiNimCo1/3Mnm02正极材料,利用X射线衍射（XRD）、扫描电镜（SEM）和电化学测试等方法对合成材料的结构、形貌以及电化学性能进行表征。结果表明：经过LaF3表面修饰的LiNi1／3C01／3Mn1／302材料保持了LiNi1／3Co1／3Mn1/302层状结构,其中LaFs表面修饰量为0．59％时,在电压为2．75-4．50V范围内,以0．3mA／cm。电流密度下经恒电流充放电测试,其首次放电比容量为172．7mAh／g,经过50周充放电循环后放电比容量为163．5mAh／g,表现出较高的初始放电比容量和良好的抗过充电性能。     

锂离子电池正极材料LiNi_(0.8)Co_(0.2)的掺杂改性研究

采用共沉淀法和成LiNi0.8Co0.2O2,探讨影响锂离子电池正极材料LiNi0.8Co0.2O2电化学性能及结构的因素.为了提高材料的电化学性能,对材料进行了掺杂改性的研究,分别掺入Al、Mn、Mg和Fe四种元素.通过在2.8～4.2V范围内的充放电测试分析,掺入Mn的正极材料LiNi0.8Co0.1Mn0.1O2具有最高的放电比容量以及最低的容量损失,其首次放电容量为168.84 mAh/g,十次循环后的放电容量为166.9 mAh/g.     

锂离子电池正极材料锰掺杂LiNi_（0.8）Co_（0.2）O_2的合成及其性能

采用共沉淀法对LiNi0.8Co0.2O2进行Mn元素的掺杂改性,考察不同掺杂量对LiNi0.8Co0.2O2材料的结构和电化学性能的影响,并对LiNi0.8-xMnxCo0.2O2（0≤x≤3）进行X射线衍射和扫描电镜分析以及循环伏安测试。充放电测试结果显示：未掺杂Mn的LiNi0.8Co0.2O2材料的初始放电比容量为164.32 mAh/g,50次循环以后为161.86 mAh/g。经掺Mn后LiNi0.8Co0.2O2材料的初始放电比容量为163.13 mAh/g,并且50次循环以后还能保持在162.33 mAh/g左右,效率达到99%以上。研究表明,掺Mn后的LiNi0.8Co0.2O2材料具有更加稳定的层状结构,并且其循环性能得到很大程度的提高。     

水热法制备LiNi_(0.5)Mn_(1.5)O_4及其电化学性能的研究

以LiOH·H2O、MnSO4·H2O和NiSO4·6H2O等为原料,采用水热法合成尖晶石LiNi0.5Mn1.5O4材料.利用扫描电子显微镜、粉末X-射线衍射仪、电化学测试分别对材料形貌、结构和电化学性能进行表征.研究加入不同锂量和热处理对尖晶石LiNi0.5Mn1.5O4材料的初始容量、放电平台以及循环性能的影响.结果表明:经过850℃热处理所合成的材料分布均匀、结晶和电化学性能良好.当LiOH溶液为0.162 g·mL-1时,尖晶石LiNi0.5Mn1.5O4材料在1 C倍率电流(140 mAh g-1)条件下,首次放电比容量为111.0 mAh·g-1.且该样品的循环性能优越:经150充放电循环后的容量衰减率仅为4.5%.     

钠离子电池正极材料Na(Fe_(1/3)Ni_(1/3)Mn_(1/3))O_2的制备及电化学性能

采用溶胶-凝胶法合成钠离子电池正极材料Na(Fe1/3Ni1/3Mn1/3)O2,通过扫描电镜、充放电测试等方法,对Na(Fe1/3Ni1/3Mn1/3)O2材料的表面形貌以及电化学性能进行研究,并探索络合剂柠檬酸用量对材料电化学性能的影响.结果表明:当柠檬酸与该材料中过渡金属总摩尔比为1∶1时,合成的Na(Fe1/3Ni1/3Mn1/3)O2材料晶粒分散均匀,粒径均一,颗粒大小约为0.5μm.电化学性能测试表明该产物具有高的放电比容量、优良的循环性能和倍率性能.在10 m A/g的电流密度下首次放电比容量为132.2 m Ah/g,25次循环之后容量仍能达到112.2 m Ah/g,容量保持率达到84.9%.在1 C的放电倍率下,其放电比容量仍能达到84.1 m Ah/g.     

正极材料LiNi_（0.4）Mn_（0.4）Co_（0.2）O_2的制备和性能

采用草酸共沉淀法合成了锂离子正极材料LiNi0.4Mn0.4Co0.2O2。用XRD、SEM和充放电实验对合成产物的结构、形貌和电化学性能进行了表征;用DSC对合成产物在不同充电状态下的热稳定性进行了研究。结果表明,采用草酸共沉淀法合成的正极材料LiNi0.4Mn0.4Co0.2O2具有α-NaFeO2型层状结构,阳离子有序度高,粒度均匀适中,电化学性能良好,首次放电比容量达到158.7 mAh/g,30次循环后放电比容量还有144.8 mAh/g;过充电状态下具有良好的热稳定性。     

Li_(1.1)Ni_(1/3)CO_(1/3)Mn_(1/3)O_2正极材料的制备与性能研究

以Li2CO3、Ni CO32Ni OH24H2O、Co CO3H2O和Mn CO3为原料,采用高温固相法,制备了Li1.1Ni1/3Co1/3Mn1/3O2正极材料.通过X射线衍射仪(XRD)和扫描电子显微镜(SEM)对材料的结构和形貌进行了表征,并采用恒电流充放电测试系统对该材料的电化学性能进行测试.结果表明:第2次球磨时加锂盐合成的Li1.1Ni1/3Co1/3Mn1/3O2样品结构完整,为-Na Fe O2型二维层状结构,属于R-3m空间群,且该样品的阳离子混排程度较低,颗粒大小比较均匀.该样品在0.1 C放电倍率和2.4~4.6 V电压范围的首次放电比容量为182.7 m Ah/g,循环57次后,容量的仍高达保持率为95.1%,表现出良好的循环性能.     

锂离子电池正极材料LiNi_(1/3-x)Nb_xCo_(1/3)Mn_(1/3)O_2的制备与表征

通过高温固相法制备了LiNi1/3-xNbxCo1/3Mn1/3O2正极材料。采用X射线衍射、扫描电镜分析以及电化学分析等手段对其微观结构、表面形貌和电化学性能进行了研究。结果表明,当x=0.005时,高温固相法能得到结晶良好的LiNi1/3-xNbxCo1/3Mn1/3O2,颗粒分布均匀,有团聚现象发生,二次团聚粒径约为10μm左右。Nb5+的引入降低了材料的阳离子混排程度,完善了材料的层状结构,提高了材料的电化学性能。在2.8~4.2V、0.2C下的首次充放电比容量分别为211.3和152.4mA·h/g。50次循环后的充放电比容量分别为127.4和124.6mA·h/g,容量保持率为97.8%,具有较好的循环性能。     

反应温度对LiNi_(0.4)Co_(0.2)Mn_(0.4)O_2组织结构及电化学性能的影响

在共沉淀法合成Ni0.4Co0.2Mn0.4(OH)2的基础上制备了锂离子电池正极材料LiNi0.4Co0.2Mn0.4O2.通过XRD,SEM和电化学测试对不同反应温度下LiNi0.4Co0.2Mn0.4O2正极材料的结构、形貌及电化学性能进行了测试和表征.测试表明随着反应温度的提高,c/a和I(003)/I(104)值也在增加,表明温度的升高可以减少锂镍离子的混排,使层状结构更加完整,进而电化学性能也更优异.900℃下反应所得到的样品,以0.2C放电,其首次放电容量为148.3mAh/g,库伦效率最高可达9.8%.循环40个周期后容量保持率为93.9%,具有较好的电化学性能.     

锂离子电池高电压正极材料LiNi_（0.5）Mn_（1.5）O_4的合成与性能

采用镍锰氢氧化物和碳酸锂为原料,在高温下合成LiNi0.5Mn1.5O4正极材料。系统地研究了不同的退火工艺对LiNi0.5Mn1.5O4结构与电化学性能的影响。研究发现,合成的样品都具有标准的尖晶石结构和规则的八面体外形。电化学测试结果表明,在700℃下退火12h得到的样品电化学性能最佳。首次放电容量达到141mAh/g,40次循环后容量保持率为99.2%,5C放电时容量仍然达到122mAh/g。     

Coating of LiNi1/3Mn1/3Co1/3O2 cathode materials with alumina by solid state reaction at room temperature

Alumina coated LiNi1/3Mn1/3Co1/3O2 particles were obtained by a simple method of solid state reaction at room temperature. The reaction mechanism of solid state reaction at room temperature was investigated. The structure and morphology of the coating materials were investigated by XRD, SEM and TEM. The electrochemical performances of uncoated and Al2O3-coated LiNi1/3Co1/3Mn1/3O2 cathode materials were studied within a voltage window of 3.00-4.35 V at current density of 30 mA/g. SEM, TEM and EDS analytical results indicate that the surface of LiNi1/3Mn1/3Co1/3O2 particles is coated with very fine Al2O3 composite, which leads to the improved cycle ability though a slight decrease in the first discharge capacity is observed. It is proposed that surface treatment by solid state reaction at room temperature is a simple and effective method to improve the cycle performance of LiNi1/3Co1/3Mn1/3O2 particles.     

Comparative experiment on layered Li（Ni1/3Co1/3Mn1/3）O2 as the alternative material for LiCoO2

This work was financially supported by the National Natural Science Foundation of China （No.50472093）.     

锂离子电池正极材料LiNi0.8Co0.2O2的合成及性能研究

以硝酸盐和淀粉为原料,采用溶胶-凝胶方法合成LiNi_0.8Co_0.2O₂锂离子电池正极材料,利用X射线衍射（XRD）、扫描电镜(SEM)和电化学测试等方法对合成材料的结构、形貌以及电化学性能进行表征。结果表明,合成材料为单一晶相的α-NaFeO₂型层状结构,颗粒小且分布均匀,在电压为2.75~4.50 V (vs. Li+/Li) 范围内,以0.2 mA/cm2电流密度下经恒电流充放电测试,其首次放电比容量为183.1 mAh/g,经过50周充放电循环后放电比容量为171.3 mAh/g,表现出较大的初始放电比容量和良好的循环性能。     

Synthesis and electrochemical characterization of LiNi0.78Co2Al0.02O2 cathode material in a novel co-precipitation method

LiNi0.78Co2Al0.02O2 cathode materials were prepared with a novel co-precipitation method followed by heat-treating. The properties of the materials were characterized. XRD patterns showed that no secondary phase appeared and the hexagonal lattice parameter c of LiNi0.78Co2Al0.02O2 was larger than that of LiNi0.8Co0.2O2. The SEM images indicated that the powders of the material were submicron size. The results of the ICP-AES analysis proved that elemental compositions of the material were similar to those of the targeted one. Cyclic voltammetry (3.0-4.2 V) illustrated that the new material had good lithium-ion intercalation/de-intercalation performance. The results of galvanostatic cycling showed that the initial specific discharge capacity of the prepared ma-terial was 181.4 mAh/g, and the specific discharge capacity was 177.3 mAh/g after 100 cycles (0.2C,3.0-4.2 V, vs. Li /Li) with the capacity retention ratio of 97.7%.     

Synthesis and electrochemical characterization of LiNi0.78Co0.2Al0.02O2 cathode material in a novel co-precipitation method

LiNi0.78 Co0.2 Al0.02O2 cathode materials were prepared with a novel co-precipitation method followed by heat-treating. The properties of the materials were characterized. XRD patterns showed that no secondary phase appeared and the hexagonal lattice parameter c of LiNi0.rsCoo.2AI~0202 was larger than that of LiNi0.8Co0.2O2. The SEM images indicated that the powders of the material were submicron size. The results of the ICP-AES analysis proved that elemental compositions of the material were similar to those of the targeted one. Cyclic voltammetry （3.0- 4. 2 V） illustrated that the new material had good lithium-ion intercalation/de-intercalation performance. The results of galvanostatic cycling showed that the initial specific discharge capacity of the prepared material was 181.4 mAh/g, and the specific discharge capacity was 177.3 mAh/g after 100 cycles （0. 2C, 3.0 - 4. 2 V, vs. Li^＋/Li） with the capacity retention ratio of 97.7%.     

Synthesis of LiNi0.8Co0.2O2 in Air Atmosphere and its Characterization

The commercialized lithium secondary cells need the electrode materials with high speeific capacity, lower pollution and lower price. Certain industrial materials ( NiSO_4, CoSO_4 , LiOH·H_2O)were used to synthesize Ni_(0.8)Co_(0.2)(OH)_2 of a stratified structure, when various synthesis conditions such as pH, reaction temperature et al. were controlled strictly. After LiOH·H_2O and Ni_(0.8)Co_(0.2) (OH)_2were calcinated in air atmosphere, LiNi_(0.8)Co_(0.2)O_2 positive electrode materials with good layered crystal structure was obtained. Tests showed that the optimal calcination temperature in air atmosphere was about at 720℃ and LiNi_(0.8)Co_(0.2)O_2 synthesized in the above conditions had good electrochemical properties and a low cost. The first specific: discharge capacity of the material was 186 mAh/g, and the specific discharge capacity was 175 mAh/g after 50 cycles at a 0.2C rate, between 3.0～4.2 V with a discharge deterioration ratio of 0.22% each cycle. Tests showed that LiNi_(0.8)Co_(0.2)O