新型电池材料LiNiyCozTi1-x-yO2的结构与性能研究

研究了新型锂离子电池材料LiNiyCozTi1-x-yO2的结构与性能,比较了LiNiyCozTi1-x-yO2与LiNiO2在充放电特性、物性、粒度分布等方面的异同,研究了LiNiyCozTi1-x-yO2的结构和电化学性能.结果表明,部分Ni被Co和Ti取代后,有效地改善了LiNiO2的性能.     

添加磷、硼、硅和铝的锂离子电池材料LiNiO2研究

研究了添加元素磷，硼硅和铝对锂离子蓄电池材料LiNiO2的影响。添加磷，硼、硅和铝的目的是提高LiNiO2的放电平台和充放电稳定性，增加循环寿命并且提高充放电能量，在n(LiOH):n(Ni(OH)2)为1.1:1.0的材料中分别加入P2O5;H3BO3,SiO2,Al2O3，保持4种元素与锂的摩尔比值分别为0.01,0.02,0.03,0.04和0.05，分析测定了样品的充放电曲线和循环伏安曲线，并采用XRD对样品的放电过程和合成产品进行了结构分析，结果证明，当n(P)/n(Ni)=0.02,n(B)/n(Ni)=0.03,n(Si)/n(Ni)\0.02,n(Al)/n(Ni)=0.02时，LiNiO2的放电电压提高，添加元素使LiNiO2在充放电过程中的晶型转变过程发生改变，使六方晶系向单斜晶系转变的趋势变小，这将改善LiNiO2的循环性能，但没有影响锂离子的嵌入和脱嵌机理，XRD分析表明，添加磷和铝使LiNiO2的层状结构更完善，同时增加了活性，但添加硼和硅以后，LiNiO2的XRD图上的衍射峰（003）强度度减弱，衍射峰（018）和（019）峰也有改变，这证明B和Si影响了LiNiO2性能。     

高容量正极材料0.08LiCo0.75Al0.25O2-0.92LiNiO2的合成与电化学性能研究

在恒定pH值下将层状钴铝双羟基复合金属氧化物(CoAl-LDH)均匀包覆在球状Ni(OH)2表面,与LiOH.H2O混合均匀后,经高温煅烧制得钴铝酸锂包覆镍酸锂0.08LiCo0.75Al0.25O2-0.92LiNiO2正极材料.电化学测试表明,0.08LiCo0.75Al0.25O2-0.92LiNiO2正极比容量高,具有良好的倍率性能和循环寿命,其0.1C放电比容量为211 mAh·g-1,0.5C放电比容量为195.6 mAh·g-1,3C放电比容量为161 mAh·g-1,0.5C 30周期循环后容量保持率为93.2%,明显优于LiNiO2和钴酸锂包覆镍酸锂0.08LiCoO2-0.92LiNiO2正极.     

LiNiO2及掺杂化合物的结构与稳定性的第一性原理研究

应用第一原理局域密度泛函对LiNiO2及其掺杂化合物的晶体结构、能带结构和态密度进行了研究.结果表明:锂镍氧系正极材料是电子的良导体,在充放电过程中具有良好的稳定性,适合做锂离子电池的正极材料;在LiNiO2晶体中主要是O和Ni之间成键,镍离子和氧离子的相互作用比较强,Li在嵌入层状结构材料后部分失去电子,以离子状态存在.     

LiAl_yNi_(1-y)O_2作为锂离子电池正极材料的研究

本文采用固相反应法合成了一系列不同 y值的LiAlyNi1- yO2 材料 ,通过对其电化学性能的研究发现 ,在适当的烧结条件下 ,LixAl0 .2 5 Ni0 .75 O2 作为二次锂离子电池的正极材料 ,其耐过充性和循环性能都有明显改善 .当Li含量大于 1时 ,在高电位范围充放 (3- 4 .8V) 30次循环后仍保持着首次放电容量的 95 % ,而LiNiO2 在此电压范围内经 2 0次循环后却只有首次放电容量的 5 6 % .通过循环伏安实验表明 :性能改善的主要原因可能是由于充电过程中 ,Al3+ 的掺杂阻止了LixAl0 .2 5Ni0 .75 O2 随Li+ 离子过量脱出而发生晶型转变 .     

锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的低温燃烧合成

以LiNO3、Ni(NO3)2·6H2O、Co(NO3)2·6H2O、Mn(NO3)2、CO(NH2)2为原料,通过低温燃烧法在空气中合成了锂离子正极材料LiNi1/3Mn1/3Co1/3O2.采用XRD研究了合成产物的物相与结构,用SEM研究了合成产物的形貌,考察了点火温度、回火温度,回火时间以及锂过量对合成产物电化学性能的影响.研究结果表明,合成产物与层状LiNiO2的结构相同,属α-NaFeO2型层状结构,合成产物的粒度较小且比较均匀,并具有良好的电化学性能.采用低温燃烧法在空气中合成LiNi1/3Mn1/3Co1/3O2的最佳条件为:500℃点火,850℃回火20h,锂过量为15mol%.在此条件下得到的合成产物首次放电比容量达到158.9mAh/g.     

锂离子电池正极材料LiNi_(0.85)Co_(0.10)(TiMg)_(0.025)O_2合成及表征

以LiOH·H2O、Ni2O3、Co2O3、TiO2和Mg(OH)2为原料,应用固相反应法合成Co Ti Mg共掺杂的LiNiO2化合物LiNi0. 85Co0. 10 (TiMg)0. 025O2;TG DTA、XRD、SEM和电化学测试表明,该材料首次放电容量达182. 7mAh/g(3. 0~4. 3V, 18mA/g), 10次循环之后,容量还有 175. 5mAh/g,容量保持率为 96. 2%;与未掺杂的LiNiO2相比,该材料显示出良好的循环性能,是一种很有应用前景的锂电池正极材料.     

低共熔混合锂盐相图的绘制及应用

采用热分析法对不同组成的混合锂盐二元体系进行研究, 绘制了混合锂盐体系的步冷曲线和T-x相图, 结果表明体系均为具有最低共熔点的二元体系. LiOH-LiNO3、LiOH-LiCl、LiOH-Li2CO3及LiNO3-LiCl体系的最低共熔点分别为175.7、294.5、418.2及221.6 ℃. 利用低共熔混合物LiNO3-LiOH为锂盐与不同前驱体反应, 制备出了层状结构良好的锂离子电池正极材料LiNiO2、LiNi0.8Co0.2O2及LiNi1/3Co1/3Mn1/3O2. X射线衍射分析表明, 合成的材料具有规整的层状NaFeO2结构, 且XRD衍射峰强度之比I(003)/I(104)>2.0, 电性能测试表明, 在2.7-4.3 V(vs Li/Li+)的电压范围内进行0.1C倍率充放电, LiNiO2、LiNi0.8Co0.2O2、LiNi1/3Co1/3Mn1/3O2首次充电比容量分别达168.0、225.4、194.0 mAh·g-1, 放电比容量分别为138.4、165.8、157.7 mAh·g-1.     

MnO_2/NiCo_2O_4的静电自组装合成及其电化学性能

通过带负电荷的MnO2纳米片与带正电荷的Co-Ni层状双氢氧化物(LDHs)纳米片的静电自组装外加后续热处理合成了异质层状结构的MnO2/NiCo2O4复合物.采用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、拉曼光谱、原子吸收光谱(AAS)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对其结构和形貌进行了表征.用循环伏安(CV)、恒流充放电和电化学交流阻抗技术对其电化学性能进行了测试.研究结果表明,该方法制得的异质复合物具有多孔层状堆垛结构,这种特殊的结构不仅增大了电解液离子的接触面积,而且还为其嵌入-脱出提供了有效途径.该复合物在1 A·g-1电流密度时,-0.6-0.45 V电位窗口内的比电容达482 F·g-1,优于纯组分MnO2和NiCo2O4的电容性能.     

Studies on Synthesis and Electrochemical Performance of Li_(1+δ) Ni_(1-x)Co_xO_(2-y)F_y Cathode Materials for Lithium-ion Batteries?

It is a technological problem of LiNiO2 cathode material for lithium-ion secondary batteries because of the difficult preparation and hard purification, instable performance, remarkable capacity fading at initial discharge, worse thermal stability and safety of Ni-series cathode materials, and it is also the key factor of hindering LiNiO2 cathode material from practical applications. Recently, by doping some metal cations such as Co, Mn, Mg, Al, Cr and so on[1-5] into LiNiO2, the preparat…     

LiNi0.8Co0.2O2/CNTs Composite used as the Materials for Supercapacitor Electrodes

Stupercapacitors or electrochemical capacitors(ECs) have attracted considerable attentionas an intermediate power source between conventional capacitors and batteries since they possesshigh power density and energy density, exhibit excellent reversibility, and have long cycle life1.Conductive polymers2, electrically conductive metal oxide3,4, activated carbon5 and carbonnanotubes(CNTs) 6-9 have been used as supercapacitor electrode materials. LiNi0.sCo0.2O2 is apromising lithium battery material because it has some advantages of both LiNiO2 and LiCoO2besides its low cost and high power10.In this paper, the electrochemical properties of supercapacitors based on LiNi0.8Co0.2O2/carbonnanotubes composite and LiNi0.8Co0.2O2/acetylene black composite and CNTs in 1 mol/LLiClO4/EC+DEC [V(EC):V(DEC)=1:1] electrolyte have been investigated by means of constantcharge/discharge current tests. The experiment results show that the LiNi0.8Co0.2O2/carbon nanotubescomposite has better properties than others, and the maximun specific capacitance of thesupercapacitor can reach 284.88F/g, while the energy density is up to 158.27Wh/Kg.That discharge capacities, coulombic efficiencies and energy densities at the first cycle and themaximum value and capacity retention at the 100th cycle for supercapacitors using differentelectrode materials (A) LiNi0.8Co0.2O2/acetylene black, (B) LiNi0. 8Co0.2O2/CNTs, (C) CNTs is listedin table 1*Capacity retention rate obtained by dividing the discharge capacity at the 100th cycle by themaximum valueFrom above, the LiNi0. 8Co0.2O2/carbon nanotubes composite should be a good candidatesupercapacitor electrode material.     

回火处理对LiNi1/3Co1/3Mn1/3O2结构和电化学性能的影响

以硝酸锂、四水合乙酸镍、四水合乙酸钴、四水合乙酸锰、氨水和草酸为原料,通过共沉淀-燃烧法合成了锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2,采用XRD、SEM和充放电试验对合成产物进行了表征,研究了回火处理对合成产物结构和电化学性能的影响.实验结果表明,嫩烧反应形成的LiNi1/3C1/3Mn31/3O2结...     

AlF3包覆LiNi0.45Mn0.45Co0.10O2锂离子电池正极材料的结构表征和 电化学性能研究

通过共沉淀与固相反应法制备层状的LiNi0.45Mn0.45Co0.10O2, 并利用X射线衍射(XRD)和电子扫描显微镜(SEM)测定材料的结构和形貌. 在2.5～4.5 V范围内, 以0.1 C (28 mA•g－1)放电, LiNi0.45Mn0.45Co0.10O2正极材料的起始放电容量达到167.2 mAh•g－1, 但循环性能较差. 当采用AlF3包覆后, 材料的循环性能得到明显改善. 利用电化学阻抗谱(EIS)技术探索AlF3包覆对正极材料的电化学性能改善机理, 实验结果表明: AlF3包覆层能够阻止电解液对正极材料的溶解和侵蚀, 稳定其层状结构, 同时降低了电极界面阻抗. 因此AlF3包覆技术是一种改善LiNi0.45Mn0.45Co0.10O2材料电化学性能的有效方法和工具.     

Synthesis of high voltage (4.9 V) cycling LiNixCoyMn(1-x-y)O2 cathode materials for lithium rechargeable batteries

Layered mixed oxides LiNi(x)Co(y)Mn(1-x-y)O(2) (0 ≤x, y≤ 0.5) synthesized by a sol-gel method using tartaric acid as a chelating agent, and their structural and electrochemical properties are investigated by thermal analysis, XRD, SEM, FT-IR and XPS studies. The higher composition of Co leads to cation disorder and shrinks the cell volume. Electrochemical behaviour of the synthesized materials is evaluated by Galvanostatic charge/discharge studies using 2016 type coin cells. The cycling studies are carried out in the voltage limits of 2.7 to 4.6, 4.8 and 4.9 V at current rates of C/10 and C/5 respectively. The composition LiNi(0.4)Co(0.1)Mn(0.5)O(2) exhibits an average discharge capacity of 192 mA h g(-1) at the current density of 0.612 mA cm(-2) (C/5) in the voltage range of 2.7-4.9 V as compared to the discharge capacity of 155 and 175 mA h g(-1) in the potential range of 2.7-4.6 and 2.7-4.8 V over the 50 investigated cycles. The effect of higher charge voltage at 4.9 V on the electrochemical performance of LiNi(x)Co(y)Mn(1-x-y)O(2) oxide materials has not previously been reported.     

共沸蒸馏法制备高性能LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2正极材料

三元复合氧化物镍钴锰酸锂(LiNi1/3Co1/3Mn1/3O2)因兼有LiNiO2和LiCoO2的优点,被认为是最有可能取代LiCoO2的新型正极材料而受到广泛关注.本文采用一种改进的共沉淀方法合成了LiNi1/3Co1/3Mn1/3O2,以共沸蒸馏干燥前驱物.结果表明,共沸干燥法最终得到的产物比普通干燥法得到的产物具有更高的比容量、更好的循环性能以及更优的倍率性能.究其原因,可归结为共沸干燥得到的样品颗粒更小,且粒径分布更均匀,球形度高,比表面积大,促进了锂离子的扩散,因而提高了其电化学性能.     

湿化学法合成LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2及其表征(英文)

利用琥珀酸为鳌合剂的湿化学法成功合成了一系列锂离子电池正极材料LiNi1/3Mn1/3Co1/3O2,在合成过程中改变琥珀酸与金属离子摩尔比(R)并研究了这一参数对合成LiNi1/3Mn1/3Co1/3O2材料物理及电化学性质的影响.采用热重、X射线衍射、Rietveld精修、扫描电镜以及超导量子干涉仪对反应机理、材料的结构、形貌以及磁学性质进行了详细表征.得到最佳合成条件为R=1,此时LiNi1/3Mn1/3Co1/3O2的阳离子混排度最低.此外,通过Rietveld精修得到该材料阳离子混排度的结果与通过磁学方法得到的结果定量相符,如对于在R=1条件下合成的样品,Rietveld精修结果显示其阳离子混排度为1.85%,而超导量子干涉仪的测试结果为1.80%.当充放电区间为3.0-4.3V,电流密度为0.2C(1C=160mA·g-1)时,该样品的首次放电容量为161mAh·g-1,库仑效率为93.1%,经过50次循环后,容量保持率可达91.3%.     

Effect of Various Synthesis methods on the Electrochemical Properties of LiNi1/3Co1/3Mn1/3O2

Layered LiNi1/3Co1/3Mn1/3O2 has the isostructure of α-NaFeO2 and shows high rate capacity with stable cycleability. Furthermore, the thermal behavior of this material is milder than that of lithium nickel oxide and lithium cobalt oxide. In addition, it is expected to be stable at elevated temperatures. Therefore LiNi1/3Co1/3Mn1/3O2 may be the most promising cathode materials of lithium-ion secondary battery.In this research, LiNi1/3Co1/3Mn1/3O2 was prepared by solid-state reaction, sol-gel method and mixed hydroxide method. The influences of synthesis method on the physical and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), charge/discharge cycling cyclic voltammetry and differential scanning calorimetry (DSC). XPS studies show that the predominant oxidation states of Ni, Co and Mn in the LiNi1/3Co1/3Mn1/3O2 compound are 2+, 3+ and 4+. From the voltage profile and cyclic voltammetry, the redox processes occurring at ～3.8V and ～4.5V are assigned to the Ni2+/Ni3+ and Co3+/Co4+ couples, respectively. Different preparation methods result in the difference in morphology (shape, particle size and specific surface area) and electrochemical behaviors. A sample prepared by solid-state reaction has the worst electrochemical performance among these three methods. Sample synthesized by mixed hydroxide method displays the better rate capacity than that prepared by sol-gel method, while the capacity retention of sample prepared by sol-gel method is superior to that synthesized by mixed hydroxide method.     

LiNi_(0.8)Co_(0.2)O_2的络合法合成及其电化学性能研究

采用络合法制备了锂离子电池的活性正极材料LiNi0.8Co0.2O2粉体,该合成材料结晶良好,层状结构发育完善.电池充放电测试表明,作为锂离子电池正极,其电化学性能与LiNi0.8Co0.2O2粉体的合成温度有关,其中以900℃下合成得到的材料性能最优:第1次放电比容量高达142mAh/g,循环30次后可逆比容量仍高达122mAh/g,容量损失为14.5%.文中对容量退化的原因进行了分析.     

Al掺杂量对正极材料LiNi_(1/3)Co_(2/3-x)Al_xO_2结构和电化学性能的影响

以共沉淀法合成的前驱体Ni1/3Co2/3-xAlx(OH)2与低共熔锂盐0.38LiOH·H2O-0.62LiNO3制备了锂离子电池正极材料LiNi1/3Co2/3-xAlxO2(x=1/12,1/6,1/3,1/2,7/12).采用X射线衍射(XRD)、扫描电镜(SEM)和电化学性能测试对其结构、形貌和电化学性质进行表征.结果表明,LiNi1/3Co2/3-xAlxO2在1/12≤x≤1/3范围内可以保持单一的六方层状α-NaFeO2结构,当Al掺杂量(x)高于1/3时,会出现杂相.其中,LiNi1/3Co1/3Al1/3O2结晶程度最高,阳离子混排效应最小,并且颗粒小而均匀,振实密度可以达到2.88g·cm-3,首次放电容量为151.5mAh·g-1,循环50次后放电容量保持在91.4%,在1C和2C倍率下放电容量仍可达到133.7和120.9mAh·g-1.