Si4+和F-掺杂对LiNi1/3Co1/3Mn1/3O2结构和电化学性能的影响

以Li2CO3、NiO、Co2O3、MnO2、LiF和SiO2为原料,采用机械力活化固相法制备了Si4+和F-掺杂的锂离子电池正极材料LiNi1/3Co 1/3Mn1/3O2.通过X射线衍射(XRD)、扫描电镜(SEM)和电化学性能测试等技术研究了LiNi1/3Co1/3Mn1/3O2的结构特征、形貌及电化学性能等.结...     

Li2Fe1-xMnxSiO4正极材料的合成及电化学性能

采用真空固相法成功地合成了锂离子电池正极材料Li2Fe1-xMnxSiO4,并用FTIR、XRD和电化学性能测试对材料进行了表征.FTIR和XRD测试表明,Mn很好地崮溶到Li2FeSiO4中.电化学性能测试表明,当w≌w(Mn)=0.1%时,合成的Li2Fe1-xMnxSiO4电化学性能最佳,首次放电容量达到67.7 mAh/g,20次循环后容量仍保持在44.8 mAh/g.     

Li(Ni1/3Co1/3Mn1/3)O2/Ag电极材料的制备及电化学性能

以碳酸盐为沉淀剂,采用共沉淀法合成晶型良好的亚微米级Li(Ni1/3Co1/3Mn1/3)O2粉末,并将其与AgNO3复合,采用无电流分解沉积法制备出了Ag表面修饰的Li(Ni1/3Co1/3Mn1/3)O2/Ag电极材料.利用X-射线衍射、扫描电镜及电化学测试等方法表征材料的结构、形貌和电化学性能.结果表明:Ag单质的存在可明显改善Li(Ni1/3Co1/3Mn1/3)O2的电化学性能,尤其是倍率特性,以0.2C、0.5C、1C倍率放电进行测试,经过40次循环后比容量分别为156.2、144.3、137.7mAh·g-1,其容量保持率分别为96.2％、95.3％、93.9％.Ag的表面修饰能使Li(Ni1/3Co1/3Mn1/3)O2电荷转移阻抗大幅度减小,阻抗从65Ω减小到50Ω.     

Li_(1+x)Ni_(0.166)Co_(0.166)Mn_(0.667)O_(2.175+x/2)正极材料的喷雾干燥法合成及电化学性能

采用喷雾干燥法制备锂离子电池用层状富锂锰基正极材料Li(1+x)Ni0.166Co0.166Mn0.667O(2.175+x/2)(x=0.3,0.4,0.5,0.6),通过X射线衍射(XRD)、扫描电子显微镜(SEM)、等离子体发射光谱(ICP)、热重-差热分析(TG-DSC)、比表面积、粒度分布和恒流充放电等测试手段对材料的结构、形貌及电化学性能进行表征。结果表明:所制得的富锂锰基正极材料为三方层状结构(mR3)的LiNi1/3Mn1/3Co1/3O2和单斜层状结构(C2/m)的Li2MnO3组成的固溶体,且具有多孔球形形貌。当x=0.4时,材料具有最优的电化学性能。在2.0~4.8 V电压范围内,25 mA/g电流密度下材料的首次放电比容量高达277.5 mA·h/g,20周循环后容量保持率达95.3%,500 mA/g电流密度下放电比容量仍达192.5 mA·h/g。     

Li2Mn1-xMgxSiO4正极材料合成与电化学性能

采用固相法合成了Li2Mn1-xMgxSiO4掺杂型正极材料,并用TG-DTA、XRD、SEM和电化学性能测试对材料进行了表征。前驱体的TG-DTA曲线和XRD物相分析表明,合成Li2MnSiO4时优化的煅烧温度为750℃。XRD测试表明Li2Mn1-xMgxSiO4具有正交结构,对应Pmn21空间群,掺镁可以提高样品主相的结晶度。掺Mg对微观形貌影响明显,适量掺杂可以得到粒径均匀、少团聚的亚微米级粉体。将Li2Mn1-xMgxSiO4组装成扣式电池进行电化学测试的结果表明,Li2Mn0.98Mg0.02SiO4样品性能最好,首次放电比容量达到124.6mAh/g,为理论容量的38%,循环20次后放电容量仍有60mAh/g。     

锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的制备及性能研究

采用溶胶-凝胶法制备了锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2,并考察了烧结温度对材料结构、表面形貌和电化学性能的影响.XRD和SEM测试结果表明,900℃下烧结得到的样品是粒径在0.3～0.5 μm范围的球形粒子,具有最佳的阳离子有序度;充放电测试结果表明,其在0.1C倍率下首次放电容量达到148.8...     

高容量正极材料Li[Li0.2Ni0.2Mn0.6]O2的合成及电化学性能

以LiOH.H2O、Ni(OH)2和Mn3O4为原料,采用固相法合成锂离子电池正极材料Li[Li0.2Ni0.2Mn0.6]O2。通过X射线衍射(XRD)、扫描电子显微镜(SEM)对所得样品的结构和形貌进行表征,并测试了该材料的倍率性能和高低温性能。结果表明:900℃下烧结10 h后可获得晶粒细小均匀的层状Li[Li0.2Ni0.2Mn0.6]O2材料,并具有良好的电化学性能,放电容量最高可达235.9 mA.h/g;在50℃下测试时该材料的放电容量高达284.4 mA.h/g,并表现出良好的循环性能,其倍率性能和低温性能还有待进一步改善。     

Zn掺杂对LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2结构与电化学性能的影响

用溶胶凝胶法制备了Li Ni1/3Co1/3-x Mn1/3Znx O2(x=0,1/24,2/24,4/24)锂离子电池正极材料。由X射线衍射和扫描电镜对其分析结果表明,Zn掺杂不改变Li Ni1/3Co1/3Mn1/3O2的α-Na Fe O2层状结构,当掺杂量达到4/24时,杂相产生。电化学研究表明,当Zn掺杂量为2/24时,Li Ni1/3Co1/3Mn1/3O2首次放电容量由未掺杂的169.2 m Ah·g-1降低为160.1m Ah·g-1,但循环性能明显提高,30次循环后的容量保持率由未掺杂的89.2%升至97%。并且在20、40、60和80 m A·g-1不同的电流密度下继续循环20次后,当再次恢复到20 m A·g-1的电流密度时,放电容量可恢复到150.3 m Ah·g-1。     

Surface Modification of Li1.6(Fe0.2Ni0.2Mn0.6)O2.6 by V2O5- Coating

在采用低温共沉淀-水热-煅烧法合成锂离子电池Fe-Ni-Mn体系正极材料Li1.6(Fe0.2Ni0.2Mn0.6)O2.6的基础上,对合成的材料Li1.6(Fe0.2Ni0.2Mn0.6)O2.6进行V2O5的包覆改性研究,以提高材料Li1.6(Fe0.2Ni0.2Mn0.6)O2.6的首次放电比容量和循环性能。用XRD、SEM、TEM、ICP光谱和恒流充放电测试研究包覆材料的结构和电化学性能。结果表明,V2O5包覆并没有改变材料的晶体结构,只存在于材料的表面,与未包覆的材料相比,V2O5包覆后的材料具有更好的首次放电容量和容量保持率。50周循环后,添加质量分数3%V2O5样品Li1.6(Fe0.2Ni0.2Mn0.6)O2.6的放电比容量可以维持在200.3 mAh/g,大于未添加V2O5样品Li1.6(Fe0.2Ni0.2Mn0.6)O2.6的194.0 mAh/g。CV测试表明,包覆层的存在有效抑制了材料层状结构的转变及电极与电解液的负反应。     

AlF3包覆锂离子电池正极材料Li1.2(Mn0.54Ni0.16Co0.08)O2的制备、表征及电化学性能（英文）

采用溶胶-凝胶法合成锂离子电池正极材料Li1.2(Mn0.54Ni0.16Co0.08)O2,并用Al F3对这种材料进行表面包覆改性。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、高分辨率透射电子显微镜(HRTEM)等表征材料的结构和形貌。结果表明,合成的Li1.2(Mn0.54Ni0.16Co0.08)O2具有典型的层状α-Na Fe O2结构,AlF3均匀包覆在Li1.2(Mn0.54Ni0.16Co0.08)O2材料表面,包覆层厚度为5~7 nm。电化学测试表明,包覆Al F3后材料的电化学性能得到提高,在1C倍率下,包覆的AlF3材料的首次放电容量为208.2 m A·h/g,50次循环后容量保持率为72.4%,而未包覆AlF3的材料的首次放电容量和容量保持率分别为191.7 m A·h/g和51.6%。     

前处理工艺对Li[Ni1/3Mn1/3Co1/3]O2正极材料结构、形貌和电化学性能的影响（英文）

以[Ni1/3Co1/3Mn1/3]3O4和氢氧化锂为原料,分别采用球磨法和液相法前处理工艺制备层状正极材料Li[Ni1/3Mn1/3Co1/3]O2。采用X？射线衍射（XRD）、场发射扫描电镜（FESEM）、恒流充放电等手段对材料的物理和电化学性能进行表征。结果表明：采用不同前处理工艺制备出的Li[Ni1/3Mn1/3Co1/3]O2材料在结构、形貌和电化学性能上有较大差异;与球磨处理法制备的材料相比,采用液相法前处理工艺制备的Li[Ni1/3Mn1/3Co1/3]O2不但保持了前驱体较好的球形形貌,同时还具有较好的循环稳定性和倍率性能;该样品在20mA/g电流密度下,首次放电容量为178mA·h/g,50次循环后,容量保持率达98.7%;在1000mA/g电流密度下,样品容量为135mA·h/g。     

Synthesis of LiCoxNi1-xO2 cathode materials from electrolysis Co-Ni alloys

The LiCox Ni1-xO2 （x= 0.2, 0.5 and 0.8） cathode materials were synthesized by sintering the mixtures of lithium salt and Cox Ni1-x （OH）2 （x= 0.2, 0.5 and 0.8） which were achieved from corresponding Cox Ni1-x alloys by electrolysis technique. The structure and electrochemical characteristics of the obtained LiCoxNi1-xO2 were studied by XRD, SEM, PSCA and charge-discharge cycling test. The results show that the electrochemical capacities of the LiCoxNi1-xO2（x=0.2, 0.5 and 0.8） materials are improved with the increase of the Ni content. The electrochemical, performance of LiCo0.2 Ni0.8O2 made in oxygen atmosphere has higher charge-discharge capacity and better cycl.eabil.ity compared with the one made in air atmosphere.     

Uniform AlF3 thin layer to improve rate capability of LiNi1/3Co1/3 Mn1/3O2 material for Li-ion batteries

LiNi1/3Co1/3Mn1/3O2 was coated with uniform nano-sized AlF3 layer by chemical precipitation method to improve its rate capability. The samples were characterized by X-ray diffractometry (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), charge-discharge cycling, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Uniform coated layer with a thickness of about 3 nm was observed on the surface of LiNi1/3Co1/3Mn1/3O2 particle by TEM. At 0.5C and 2C rates, 1.5% (mass fraction) AlF3-coated LiNi1/3Co1/3Mn1/3O2/Li in 2.8-4.3 V versus Li/Li+ after 80 cycles showed less than 3% of capacity fading, while those of the bare one were 16.5% and 45.9%, respectively. At 5C rate, the capacity retention of the coated sample after 50 cycles maintained 91.4% of the initial discharge capacity, while that of the bare one decreased to 52.6%. EIS result showed that a little change of charge transfer resistance of the coated sample resulting from uniform thin AlF3 layer was proposed as the main reason why its rate capability was improved obviously. CV result further indicated a greater reversibility for the electrode processes and better electrochemical performance of AlF3-coated layer.     

Synthesis and electrochemical properties of Li[NixCoyMn1-x-y]02 (x, y=2/8, 3/8) cathode materials for lithium ion batteries

The uniform layered Li(Ni2/8Co3/8Mn3/8)O2, Li(Ni3/8Co2/8Mn3/8)O2, and Li(Ni3/8Co3/8Mn2/8)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(Ni3/8Co3/8Mn2/8)O2 cathode material calcined at 900℃ for 10 h. The well-ordered Li(Ni3/8Co3/8Mn2/8)O2 synthesized under the optimal conditions has the I003/I104 ratio of 1.25 and the R value of 0.48 and pedance of 558 Ω after the first cycle. The decrease of Ni content results in the decrease of discharge capacity and the bad cycling perform-ance 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 electro-chemical properties of the Li-Ni-Co-Mn-O cathode materials.     

Effects of sodium substitution on properties of LiMn2O4 cathode for lithium ion batteries

Na-doped Li1.05Mn2O4 cathodes were synthesized using a sol-gel process.The samples were characterized by X-ray diffractometry(XRD),cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS)and charge-discharge measurements. The results show that all the samples exhibit the same cubic spinel phase structure without impurity.The lattice constant and unit cell volume decrease with increasing the sodium dopant amount.As the molar ratio of sodium to manganese(x=n(Na)/n(Mn))increases from 0 to 0.03,the initial discharge capacity of the Li1.05Mn2O4 cathodes decreases from 119.2 to 107.9 mA·h/g,and the discharge capability at large current rate and the storage performance decline dramatically,while cycling performance at room temperature and 55℃are improved.The CV and EIS studies indicate that reversibility of Li1.05Mn2O4 cathodes decreases and the electrochemical impedance increases with increasing the sodium dopant amount.     

Synthesis and characterization of LiCo1/3Ni1/3Mn1/3O2 prepared by Pechini process

Layered cathode material LiCo1/3Ni1/3Mn1/3O2 was synthesized by Pechini process, and investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and galvanostatic charge/discharge cycling. The sample is well-crystallized and has a phase-pure a-NaFeO2 structure. The particle sizes are uniform, and distributed in the range of 20-200 nm. The initial discharge capacity of the Li/LiCo1/3Ni1/3Mn1/3O2 cell was about 149 mAh·g -1 when it was cycled at a voltage range of 4.5-2.3 V with a specific current of 0.25 mA. The result is better in comparison with solid-state solution method. The synthetic procedure was discussed. Three major reactions: chelation, esterification, and polymerization successively occurred.     

LiMgxNi0.5-xMn1.5O4的制备和电化学性能

为改善LiNi0.5Mn1.5O4的电化学性能,采用流变相法合成掺镁的锂离子电池正极材料LiMgxNi0.5-xMn1.5O4(x=0,0.05,0.1)。XRD测试结果表明所得材料仍为尖晶石结构。电化学性能测试结果显示:当x取值0.1,在3.5～4.9V电压范围内进行充放电循环时,材料LiMg0.1Ni0.4Mn1.5O4具有较好的循环性能,1C充放电时,初始放电比容量可达110.22mAh/g,30次循环后容量衰减率仅为7.7%。     

Effects of synthesis conditions on the structural and electrochemical properties of layered LiNi1/3Co1/3Mn1/3O2 cathode material via oxalate co-precipitation method

The uniform layered LiNi1/3Co1/3Mn1/3O2 cathode material for lithium ion batteries was prepared by using (Ni1/3Co1/3Mn1/3)C2O4 as precursor synthesized via oxalate co-precipitation method in air. The effects of calcination temperature and time on the structure and electrochemical properties of the LiNi1/3Co1/3Mn1/3O2 were systemically studied. XRD results revealed that the optimal calcination conditions to prepare the layered LiNi1/3Co1/3Mn1/3O2 were 950°C for 15 h. Electrochemical measurement showed that the sample prepared under the such conditions has the highest initial discharge capacity of 160.8 mAh/g and the smallest irreversible capacity loss of 13.5% as well as stable cycling performance at a constant current density of 30 mA/g between 2.5 and 4.3 V versus Li at room temperature.