锂离子电池Li（Ni3／8Co3／8Mn2／8）O2层状正极材料的制备与电化学性能

采用液相共沉淀方法合成锂离子电池用Li(Ni3/8Co3/8Mn2/8)O2正极材料,以XRD、SEM、原子吸收光谱法和电池充放电循环测试方法表征Li(Ni3/8Co3/8Mn2/8)O2粉末的结构和性能.结果表明:900℃焙烧10 h合成的Li(Ni3/8Co3/8Mn2/8)O2粉末样品具有较好的综合电化学性能和良好的六角层状结构,阳离子混合度小,六角晶格有序性高,颗粒为由小晶粒结合而成的多晶体,平均粒径约为4.5 μm,I003/I104为1.25,R值为0.48,首次放电容量为172.9 mA·h/g(2.8～4.5 V,0.1C倍率),0.2C倍率循环20次后电容量为首次循环放电容量的96.1%.     

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[Li0.2Ni0.15Mn0.55Co0.1-xCrx]O2-yCly富锂正极材料的合成及电化学性能研究

采用溶胶-凝胶法合成富锂正极材料,900℃煅烧12 h得到产物Li[Li0.2Ni0.15Mn0.55Co0.1-xCrx]O2-yCly。X射线衍射光谱(XRD)测试表明,材料均具有层状α-NaFeO2结构;扫描电镜(SEM)观察材料颗粒均匀,粒径达到纳米范围;充放电测试显示,Cl-、Cr3+共掺材料在2~4.8 V电压范围及0.1 C倍率下,20℃时,首次放电比容量达到239.8 mAh·g-1,首次库伦效率为81.2%;55℃时,首次放电比容量和首次库伦效率分别为308.3 mAh·g-1和92.7%。并且40个循环之后在1 C倍率下,材料在20和55℃时放电比容量仍分别达到173.5和207.7 mAh·g-1。     

Synthesis and electrochemical characterization of layered Li[Ni1/3CO1/3 Mn1/3]O2 cathode material for Li-ion batteries

1 INTRODUCTIONDue to the high cost of LiCoO2,a commonlyused cathode material in commercial rechargeablelithium-ion batteries , much efforts have been madeto develop cheaper cathode materials than LiCoO2,Li Ni O2and Li MnO2have been studied extensivelyas possible alternatives to LiCoO2[1 4 ]. Stoichio-metric Li Ni O2is knownto be difficult to synthesizeandits multi-phase reaction during electrochemicalcyclingleads to structural degradation,andlayeredLi MnO2has a significant drawback…     

Li(Mn1/3Ni1/3Co1/3)1-yMyO2(M=Al,Mg,Ti)正极材料的制备及性能

采用液相共沉淀合成锰镍钴氢氧化物前驱体, 在前驱体中掺入元素M(M=Al, Mg, Ti), 与锂结合生成Li(Mn1/3Ni1/3Co1/3)0.98M0.02O2材料, 结果表明掺杂可有效提高材料的循环性能. X射线衍射结果表明 随掺钛量增大(0≤y≤0.15), 晶格畸变增大, 半高宽变大, 晶粒粒径增大; 其中掺钛量y=0.1的材料电化学性能表现最好, 以20 mA/g电流充放电, 在2.5～4.6 V电压区首次放电容量可达215 mA·h/g.     

正极材料Li（Ni1／3Co1／3-xMn1／3）MxO2（M=Ti，Mg）的合成及性能

采用草酸盐前驱体合成Ti4+、Mg2+掺杂正极材料Li(Ni1/3Co1/3-xMn1/3)MxO2(M=Ti, Mg).利用XRD和SEM对其结构和形貌进行表征,并采用循环伏安、交流阻抗、恒流/恒压充放电测试其电化学性能.结果表明:Ti4+、Mg2+掺杂后晶胞体积增大,大倍率充放电时LiNi1/3Co1/3Mn1/3O2的电化学反应阻抗Rct降低,其大倍率充放电性能得到改善,Ti4+掺杂效果更好;当掺杂量x＝0.025时,材料晶型完整,具有单一的a-NaFeO2层状结构;1C倍率时Li(Ni1/3Co1/3-0.025Mn1/3)Ti0.025O2的第二循环放电容量为143.2 mA-h/g,2C时为128.0 mA-h/g,经100次循环后容量分别为132.5和115.8 mA-h/g,容量保持率为92.53%和90.47%.     

初始Li/(Mn+Ni)摩尔比对LiNi0.5Mn0.5O2电化学性能的影响

以Li2CO3,MnCO3和Ni(OH)2为原料,采用一步固相反应制备锂离子电池层状结构正极材料LiNi0.5-Mn0.5O2,采用X射线衍射和扫描电镜对其结构和形貌进行表征,并研究配料时不同初始Li/(Mn Ni)摩尔比(1.0,1.05,1.1,1.2,1.5)对LiNi0.5Mn0.5O2电化学性能的影响。X射线衍射结果表明,在600℃预烧12 h而后800℃烧结24 h的条件下各样品结晶完整,初始Li/(Mn Ni)摩尔比为1.5时样品有未知相杂质生成。扫描电镜分析表明,随着初始Li/(Mn Ni)摩尔比的增大,颗粒团聚加剧。电化学测试结果表明,随着初始Li/(Mn Ni)摩尔比(≥1.05)的提高,初始容量有下降趋势。初始Li/(Mn Ni)摩尔比为1.05和1.1时样品首次放电容量分别为167.0 mA.h/g和147.2 mA.h/g,循环20次后容量保持率分别为88.2%和97.8%。     

正极材料LiNi0.8Co0.1Mn0.1O2的合成及电化学性能

将液相共沉淀法制备的Ni0.8Co0.iMn0.1(OH)2与LiOH·H2O混合,固相烧结合成微米级的LiNi0.8Co0.1Mn0.1O2正极材料.XRD谱表明,合成的LiNi0.8Co0.1Mn0.1O2正极材料为典型的α-NaFeO2层状结构,无杂质峰;从SEM像可以看出,产物颗粒为类球形,分散性好,由一次粒子紧密堆积而成,平均粒径为3 μm;电化学测试结果表明,在2.8～4.3 V电压范围内,750℃焙烧15h合成的LiNi0.8Co0.1Mn0.1O2材料的电化学性能最优,0.1C时,其首次放电容量为186.748mA·h/g,分别高于700和800℃时的首次放电容量172.947和180.235mA·h/g.材料在0.5和2C时循环40次后,容量保持率分别为98.32％和88.72％,循环性能良好.     

Synthesis and characterization of layered Li（Ni1/3Mn1/3CO1/3）O2 cathode materials by spray-drying method

Spherical Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 was prepared via the homogenous precursors produced by solution spray-drying method. The precursors were sintered at different temperatures between 600 and 1 000 ℃ for 10 h. The impacts of different sintering temperatures on the structure and electrochemical performances of Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 were compared by means of X-ray diffractometry(XRD), scanning electron microscopy(SEM), and charge/discharge test as cathode materials for lithium ion batteries. The experimental results show that the spherical morphology of the spray-dried powers maintains during the subsequent heat treatment and the specific capacity increases with rising sintering temperature. When the sintering temperature rises up to 900 ℃ , Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 attains a reversible capacity of 153 mA·h/g between 3.00 and 4.35 V at 0.2C rate with excellent cyclability.     

Li,Mn源对LiMn2O4尖晶石高温电化学性能的影响

采用熔盐浸渍法用LiNO3或LiOH·H2O作为Li源，以电解二氧化锰(EMD)或化学二氧化锰(CMD)作为Mn源，制备了4种尖晶石型LiMn2O4正极材料．对材料进行了XRD结构表征，采用最小二乘法计算了样品的晶格常数，以BET法测定了各样品的比表面积，测定了各样品的电导率；检测了各样品在高温下的贮藏和循环性能，在高温下作了循环伏安分析．结果表明，虽然各样品均属于立方尖晶石结构，但晶格常数、电导率和比表面积均不相同．以LiOH·H2O和EMD为原料制得的样品的极化最小，在高温下的贮藏性能和循环性能最好     

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...     

LiOH-Li_2CO_3低共熔混合锂盐体系合成LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2

利用低共熔组成的0.24LiCO3-0.76LiOH混合锂盐体系,与钴、镍、锰的球形氢氧化物按1.1:1混合,无需前期球磨,直接经二段控温程序制备出锂离子正极材料LiNi1/3Co1/3Mn1/3O2。X射线衍射分析表明合成的Li(Ni1/3Co1/3Mn1/3)O2结晶度高,具有规整的层状α-NaFeO2结构,扫描电镜显示产物颗粒均匀,振实密度高达2.89g·cm-3,显著高于用单一锂盐制备的同样产品(2.4g·cm-3)。充放电测试表明,材料具有良好的电性能,首次充放电容量为176和166mhA·g-1,循环50次后,材料的电性能没有明显的衰减。     

快速共沉淀过程pH值对Ni_(0.8)Co_(0.1)Mn_(0.1)(OH)_2及LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2性能的影响

采用快速共沉淀法制备Ni0.8Co0.1Mn0.1(OH)2前驱体,利用前驱体与LiOH.H2O的高温固相反应得到锂离子电池层状正极材料LiNi0.8Co0.1Mn0.1O2,探讨pH值对材料结构和电化学性能的影响。通过X射线衍射(XRD)、扫描电镜(SEM)和电化学测试对合成样品进行表征。结果表明,pH值为11.00~12.00时,合成的Ni0.8Co0.1Mn0.1(OH)2前驱体均无杂相;pH值为11.50时,合成的前驱体制备出的正极材料具有良好的电化学性能,0.1C倍率下首次放电比容量为192.4 mA.h/g;经过40次循环,容量保持率为91.56%。     

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.     

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%.     

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.     

Synthesis and electrochemical properties of nanocrystalline Li[Li1／3Ti5／3O4] by complex sol-gel method

1　INTRODUCTIONSpinelLi[Li1/3Ti5/3O4 ]isaveryattractiveelec trodematerialforitsexcellentcyclelifeandpromisingchargingrateinrechargeableenergystoragecells .Duringelectrochemicalreactionsconsistingofelectronandlithiumioninsertionintoorextractionfromit,itslatticeconstantchangesveryslightly ,soitiscon sidereda“zero strain”insertioncompound[13] .Thismaterialwassuccessfullyusedasanodecoupledwithhighpotentialcathodematerials (LiMn2 O4 ,LiCoO2oractivecarbonfiber)toprovideacellorhybridsu perc…