锂钛氧嵌锂负极材料的研究进展

目前锂离子电池主要受制于安全性能、大功率性能和制造成本,新型高性能锂钛氧基负极材料有望解决这些问题,在动力型和储能型锂离子电池中获得应用。本文对Li4Ti5O12、Li Ti2O4、Li2Ti3O7、Li2Ti6O13等系列锂钛氧嵌锂化合物的晶体结构、电化学性能、制备方法、化学改性、应用研究等方面的重要成果进行了较全面的阐述,并指出了未来研究发展方向。     

模板法制备锂离子电池负极材料钛酸锂的机理与研究

以四氯化钛、氢氧化锂为原料,采用模板法,获得前躯体,再通过煅烧得到纳米钛酸锂。最佳制备工艺条件为模板:钛摩尔比为4∶1,煅烧温度为800℃。对反应机理进行初步研究,证明本工艺得到的前躯体为(Li1.81H0.19)Ti2O5·0.2625TiO2·2H2O,最后生成的产物为Li4Ti5O12。     

石墨烯/钛酸锂复合材料制备研究

采用易于工业化的固相法合成Li4Ti5O12以及Hummers法制备氧化石墨烯,并以N2H4·H2O为还原剂制备石墨烯材料,在此基础上高能球磨合成Li4Ti5O12/Grephene复合材料。借助X射线衍射、扫描电镜、能谱分析对合成的样品进行结构和形貌表征,并采用恒流充放电、交流阻抗和循环伏安等测试方法检测其电化学性能。充放电结果表明:复合前后材料形貌不发生变化,石墨烯均匀地附着在Li4Ti5O12表面。由于石墨烯具有良好的导电性,材料的倍率性能得到大幅提高。在充放电倍率为20 C时,复合材料的比容量约为120.2 m Ah·g-1,而纯相钛酸锂的比容量只有61mAh·g-1。     

二步煅烧法制备高振实密度钛酸锂负极材料

以Li2CO3和纳米TiO2为原料,通过二步煅烧固相反应法制备Li4Ti5O12负极材料。研究前驱体球磨以及球磨时间对合成Li4Ti5O12样品振实密度和电化学性能的影响。借助XRD、SEM、振实密度仪和充放电测试仪、电化学综合测试仪表征Li4Ti5O12材料的物理性能和电化学性能。结果表明:球磨工艺能够提高Li4Ti5O12的纯度,并有效提高其振实密度和电化学性能;球磨时间为2 h时,所得材料的振实密度达1.70 g/cm3,0.1C首次放电比容量为174 mA.h/g,5C放电比容量达124.2 mA.h/g。     

钛掺杂LiFePO4的还原插锂合成及其性能

用共沉淀法制备掺钛前驱体FePO4·2H2O,对FePO4·2H2O经常温还原插锂合成LiFePO4的前驱混合物,后经热处理得橄榄石型LiFePO4;用SEM,XRD和恒流充放电等对样品进行表征,考察Ti掺杂和合成温度对LiFePO4的物理和电化学性能的影响.研究结果表明,在600 ℃时合成的Ti掺杂样品具有优异的电化学性能,该样品在0.1C,1C和2C倍率下的首次放电比容量分别为150,130和125 mA·h/g,循环40次后的放电比容量均无衰减.     

Al掺杂对Li_4Ti_5O_(12)结构及性能的影响

以金红石型TiO2、Li2CO3和Al2O3为原料,采用高温固相法制备锂离子电池负极材料Li4Ti5O12和Li4AlxTi5-xO12(x=0,0.025,0.05,0.1,0.2,0.4)。利用X射线衍射仪、扫描电镜、半电池充放电测试和交流阻抗测试研究材料的物相、结构、形貌以及电化学性能。结果表明:Al掺杂不会改变Li4AlxTi5-xO12的尖晶石结构,但会导致材料颗粒尺寸增大;适当Al掺杂后,材料的循环稳定性和极化性能得到改善,充放电比容量和可逆比容量不同程度降低;Li4Al0.025Ti4.975O12具有最优的电化学性能,0.1C倍率下首次充电比容量达到156.7 mA.h/g。     

LiMn2O4/Li4Ti5O12复合材料的制备与电化学性能

以LiMn2O4、醋酸锂和钛酸四丁酯为原料,乙醇为溶剂,采用原位复合法制备LiMn2O4/Li4Ti5O12复合材料.采用X射线衍射分析、红外光谱、扫描电镜和电化学测试等手段对复合材料进行表征.结果表明,在LiMn2O4/Li4Ti5O12复合材料中晶态的LiMn2O4表面被无定形结构的Li4Ti5O12包覆,但Li4Ti5O12的存在并没有改变LiMn2O4的晶体结构.由于Li4Ti5O12的包覆,LiMn2O4的倍率性能和高温性能都得到显著提高:室温下2.0C放电时20次循环后LiMn2O4/Li4Ti5O12复合材料的可逆容量达到108.4mA·h/g,平均每次循环的容量损失只有0.053%;而55 ℃ 1.0C放电时,经60次循环后LiMn2O4/Li4Ti5O12的放电容量为109.9 mA·h/g,平均每次循环的容量损失为0.036%.     

锂离子电池极材料钽掺杂钛酸锂的制备及电化学性能

通过固相合成制备了钽掺杂材料Li4Ti4.95Ta0.05O12。通过XRD和SEM来表征Li4Ti4.95Ta0.05O12的结构和形貌。钽掺杂并没有改变本体材料的结构和形貌,而且显著提高了材料的循环性能和倍率性能。Li4Ti4.95Ta0.05O12在10C和30C倍率时的放电容量分别是116.1mA.h/g和91.0mA.h/g。Ta掺杂取代了Li4Ti5O12中的Ti的位置,产生了Ti4＋/Ti3＋混合价态,从而提高了钛酸锂的电导率。故具有优异的高倍率性能,是一种优异的锂离子电池负极材料。.     

水热法合成尖晶石型Li4Ti5O12及其电化学性能

以钛酸丁酯和乙酸锂为原料、三乙醇胺为结构导向剂,通过水热法合成前驱物,然后采用固相烧结制备Li4Ti5O12,探讨不同的钛锂比和煅烧温度对Li4Ti5O12结构和电化学性能的影响,并通过XRD、SEM、恒电流充放电和循环伏安测试对其进行表征.结果表明:当钛和锂的摩尔比为1:0.82、煅烧温度为800 ℃时,制备得到平均粒径为200 nm的纯相尖晶石型Li4Ti5O12,并具有良好的电化学性能;在0.1C倍率下,其首次放电比容量高达到181.7 mA-h/g,经过50次循环后放电比容量仍有151.5 mA-h/g,从第5次到第50次循环,平均每个循环放电比容量衰减量仅为6 μA-h/g;当电流倍率增大到2.0C时,其首次放电比容量仍然保持135 mA-h/g,从第5次到第50次循环,平均每个循环放电比容量衰减量为0.48 mA-h/g.     

二步煅烧法合成Li4Ti5O12材料的性能

采用超声活化对原材料Li2CO3和TiO2进行预处理,并采用二步煅烧方法制备Li4Ti5O12材料。利用X射线衍射仪、扫描电镜和电池充放电测试仪研究二步煅烧条件对材料结构、形貌及电化学性能的影响,并得到二步煅烧的最佳工艺。结果表明:采用600℃预烧温度制备的材料具有较高的纯度和结晶度;800℃高温煅烧温度下制备的Li4Ti5O12材料具有均一分散的颗粒结构;超声活化制备Li4Ti5O12的最佳煅烧工艺是600℃预烧8 h后800℃高温煅烧10 h,制备的材料在0.1C倍率下首次放电容量达170.6 mA.h/g,0.2C倍率下20次循环后的放电比容量由152 mA.h/g降至150 mA.h/g,容量保持率为98.7%。     

Preparation of nano-sized cerium and titanium pyrophosphates via solid-state reaction at room temperature

Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 (with x=0, 0.2, 0.5, 0.7, 0.9, and 1.0) were obtained by grinding a mixture of to remove soluble inorganic salts, and drying at 100℃. The products and their calcined samples were characterized using ultraviolet-visible spectroscopy (UV-vis), therrnogravimetry and differential thermal analyses (TG/DTA), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM). The results show that nano-sized Ce1-xTixP2O7 behave as an excellent UV-shielding material. Thereinto, the CeP2O7 has the most excellent UV-shielding effect, and the amorphous state of Ce038Ti0.2P2O7 can keep at a higher temperature than CeP2O7. Therefore, the stabilization of the amorphous state of the cerium pyrophosphates was carried out by doping titanium. This stabilization is a significant improvement, which enables to apply these amorphous pyrophosphates not only to cosmetics and paints, but also plastics and films.     

Synthesis and characterization of LiNi0.45Co0.10Mn0.45O2 cathode for lithium ion batteries

1INTRODUCTIONAdvanced rechargeable lithium ion batteriesare attractive for use in consumer electronic andelectric vehicle(EV)application because of a fa-vorable combination of voltage,energy density,cycling performance,and have been developed rap-idly worldwide during the past decade[1,2].LiCoO2has been widely used as a cathode material in com-mercial lithiumion battery because it is reasonableeasy to synthesize and shows a stable discharge ca-pacity[3].But due to its high cost and toxic…     

Electrochemical characteristics of ternary and quadruple lithium silicon nitrides as anode material for lithium ion batteries： the influence of precursors

Ternary and quadruple lithium silicon nitride anode materials for lithium ion batteries with different precursors were prepared by the simple process of high-energy ball milling.High capacity and excellent cyclability were obtained.The influence of precursor introduction on the electrochemical performance of products was investigated.This research reveals that the electrochemical performance of lithium silicon hiaide can be enhanced significantly by doping O.The cyclability of quadruple lithium silicon nitride can be optimized remarkably by controlling the introduction quantity of the precursors.It is possible for the composite to be used as a capacity compensator within a wide voltage cut-off window.     

Effect of particle size and agglomeration of TiO2 on synthesis and electrochemical properties of Li4Ti5O12

The effects of the initial condition of synthesis on electrochemical properties of Li4Ti5O12 were studied with the comparison among starting and final materials by SEM, XRD and electrochemical analysis methods. The influence of the solvents for mixing the starting material on the products was investigated. The results show that nano-sized Li4TisOlz powder obtained by nano-sized TiO2 with ethanolamine as solvent shows more excellent electrochemical performance. More than 95%, 91%, 85% and 71% of the nominal capacity is achieved respectively at 0.5C, 1C, 2C and 4C rate without excellent capacity fading after more than 30 cycles.     

Synthesis and physicochemical properties of LiLa0.01Mnt.99O3.99F0.01 cathode materials for lithium ion batteries

Spinel lithium manganese oxide cathode materials were synthesized using the ultrasonic-assisted sol-gel method.The synthesized samples were investigated by differential thermal analysis (DTA) and thermogravimetry (TG),powder X-ray diffraction (XRD),scanning electron microscopy (SEM),cyclic voltammetry (CV),and the charge-discharge test.TG-DTA shows that significant mass loss occurs in two temperature regions during the synthesis of LiLa0.01Mn1.99O3.99F0.01.XRD data indicate that all samples exhibit the same pure spinel phase,and LiLa0.01Mn1.99O3.99F0.01 and LiLa0.01Mn1.99O4 samples have a better crystallinity than LiMn2O4. SEM images indicate that LiLa0.01Mn1.99O3.99F0.01 has a slightly smaller particle size and a more regular morphology structure with narrow size distribution.The charge-discharge test reveals that the initial capacities of LiMn2O4,LiLa0.01Mn1.99O4,and LiLa0.01Mn1.99O3.99F0.01 are 130,123,and 126 mAh·g-1,respectively,and the capacity retention rates of the initial value,after 50 cycles,are 84.8%,92.3%,and 92.1%,respectively.The electrode coulomb efficiency and CV reveal that the electrode synthesized by the ultrasonic-assistexi sol-gel (UASG) method has a better reversibility than the electrode synthesized by the sol-gel method.     

锂离子电池用LiVPO4F/C基正极材料的制备和性能（英文）

将H2C2O4·2H2O,NH4H2PO4,NH4VO3和LiF通过球磨反应、烧结,合成了LiVPO4F/C基正极材料。在这个过程中,草酸起还原剂和碳源的作用,利用热重、X射线衍射、扫描电镜、透射电镜和碳-硫分析等手段对合成的前驱体和材料进行检测和分析。XRD分析表明,球磨反应后所得到的前驱体为无定形态,而烧结后的材料中除了LiVPO4F的衍射峰外,还存在Li3V2(PO4)3和V2O3衍射峰。材料颗粒均匀,尺寸约2μm。透射电镜分析表明,合成的材料颗粒表面包裹着一层约2nm厚的无定形碳。在截止电压3.0～4.4V时,合成的材料在0.1C和10C倍率下的放电比容量分别为151.3和102.5mA·h/g。在10C倍率下循环50次后容量保持率为90.4%。在LiVPO4F和Li3V2(PO4)3的循环伏安曲线中可以明显看到V3+/V4+的氧化还原峰。     

纳米氧化铝粉体的绿色合成

以廉价的铝锭和异丙醇为起始原料,采用独特的分离提纯、回收再利用技术和溶胶凝胶工艺,合成高性能纳米氧化铝粉体,并利用TEM,XRD和石墨炉原子吸收法等对粉体的相组成、形貌和杂质含量进行分析研究.得出原料对粉体的形貌和组成没有影响,两种不同的Al源均制备出了粒径为10～20nm,球形γ-Al2O3粉体;而原料和蒸馏工艺对纳米氧化铝粉体的纯度有影响,随铝锭纯度的增加,所制备的纳米氧化铝所含的微量杂质含量明显下降.和一次蒸馏相比,二次蒸馏所得产物的主要微量杂质明显下降.利用重熔铝锭为原料,采用二次蒸馏工艺,制得了纯度高达99.99%的纳米氧化铝,且在制备过程中没有废液,废气排出,实现了高纯纳米氧化铝粉体的低成本、环保型生产.     

Effect of lithium or aluminum substitution on the characteristics of graphite for anode of lithium ion batteries

Modification of graphite for anode of lithium ion batteries is investigated. Results of X-ray diffraction shows lithium and aluminum exists as Li compound (CH3COOLi-2H2O) and Al compound (AID3) in the graphite, respectiovely. The Brunauer-Emmer-Teller (BET) surface area of the modified graphite increases. According to the electrochemical measurements of Li/C cell and prototype Li-ion batteries, the Li-doped graphite has large reversible capacity of 312.2 mA·h/g, low irreversible capacity of 52.9 mA·h/g, and high initial coulombic efficiency of 85.51 %. The 063448 size proto-type battery with Li-doped graphite anode has large discharge capacity of 845 mA·h and good cycling performance. The initial charge/discharge characteristic of Al-doped graphite is close to those of undoped graphite, but the prototype battery with Al-doped anode shows the best cycling performance with capacity retention ratio of 94.06% at the 200th cycle.     

Electrochemical characteristics of single crystalline nanowires and their driven mechanism

The electrochemical characteristics of single crystalline SnO₂, ZnO and Si nanowires and their driven mechanism are reported as nanostructural anode materials. As intercalation and deintercalation of Li, Si nanowires are converted to amorphous phases of shorter wire shapes caused by the lattice expansion of the single crystalline Si, resulting in the fading of discharge capacity, although the reversible capacity (2500 mAh/g) in the first cycle is very high. However, oxide nanowries (SnO₂ and ZnO) are transformed from a single crystalline structure into a polycrystalline form consisting of nano-sized metallic particles and Li₂O crystals within the wires, which maintain their discharge capacity. The results of this study imply that the large surface area and high electrochemical activity of nanowires and nano-sized polycrystalline particles can provide a method to develop a new class of one-dimensional anode nanostructures in lithium-ion rechargeable batteries.