以LiAc·2H2O、Mn(Ac)2·4H2O、Ni(Ac)2·4H2O为原料,采用水溶液法合成锂离子电池正极材料LiNi0.5Mn0.5O2和Li1.2Ni0.3Mn0.5O2。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,并测试了该材料的电化学性能。结果表明,样品LiNi0.5Mn0.5O2首次放电比容量能达到125.6mAh/g,经过30周循环以后,放电比容量为111.2mAh/g,容量保持率为96.2%;而富锂样品Li1.2Ni0.3Mn0.5O2首次放电比容量能达到187.2mAh/g,经过30周循环以后放电比容量为184.5mAh/g,容量保持率为98.6%,远高于富锂前样品。另外,富锂后的样品Li1.2Ni0.3Mn0.5O2倍率性能优于富锂前。

Li-rich layered cathode material,LiNi0.5 Mn0.5 O 2 and Li1 .2 Ni0.3 Mn0.5 O 2 were synthesized via a solution method.The structure and morphology of the prepared materials were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM).Galvanostatic charge/discharge studies demonstrated the electrochemical performance of two materials.It was found that the material LiNi0.5 Mn0.5 O 2 delivers initial discharge capacity of 125.6 mAh/g and retains a reversible capacity of 1 1 1.2 mAh/g after 30 cycles with a capacity retention of 96.2%.While the sample Li1 .2 Ni0.3 Mn0.5 O 2 exhibited not only a higher discharge capacity of 187.2 mAh/g,but also excellent cycling performance with a capacity retention of over 98.6% after 30 cycles.In addition,the Li-rich Li1 .2 Ni0.3 Mn0.5 O 2 shows better rate capability.

用溶胶-凝胶法合成了纯尖晶石相纳米晶Li4Ti5O12,并对其形成机理进行了研究.IF分析表明,水相中与有机交联剂介质中合成的前驱体结构非常相似,柠檬酸根与Ti(Ⅳ)为单齿方式配位,钛与氧形成了[-O-Ti-O-]n聚合链;TG-DTA和XRD分析表明,前驱体热分解经历了有机物热分解、碳链断裂燃烧与Li4Ti5O12形成及晶形成长等阶段;前驱体在热分解的同时就形成了Li4Ti5O12,钛元素在反应过程中经历了锐钛矿型-TiO2中间相,700℃时已成为单一相纳米晶Li4Ti5O12;800℃合成粉末的SEM研究表明,产物粒度分布均匀,为球形颗粒的疏松多孔聚集体.

Spinel Li4Ti5O12 was prepared by sol-gel method with citric acid, titanium salt, lithium hydroxide, and the formation mechanism of Li4Ti5O12 was studied. According to IR, TGA-DTA , XRD and SEM analysis, the precursors using or without using organic crosslinking agent had similar combinative characters. Citrate could coordinate with Ti(Ⅳ) through a monodentate, and there were [-O-Ti-O-]n chains in the precursors. In air, thermal decomposition of precursors involved in organic and carbon chains oxidation, and Li4Ti5O12 crystal formation and growth. Single phase nanocrystalline Li4Ti5O12 were made at 700℃, and ana-TiO2 intermediate phase was experienced. The Li4Ti5O12 powders made at 800℃ were porous and loose aggregates, and fine particle size distribution.

以氢氧化锂和钛酸四丁酯为原料,采用水热法制备出花状纳米片簇 Li4 Ti5 O12粉体,研究了不同原料配比对产物晶体结构的影响。采用 XRD、SEM对Li4 Ti5 O12的晶体结构和形貌进行了分析,结果表明所得产物是由 Li4 Ti5 O12纳米片层组成的花状微球,所得晶体为尖晶石型结构。恒电流充放电实验表明,Li4 Ti5 O12在充放电倍率为0.1、1和2C 下首次放电比容量分别为160、141和128mAh/g。

Flower-like Li4Ti5O12 nanoplatelets were synthesized by a hydrothermal method using Ti(OC4H9)4 and LiOH·H2 O as the raw materials.The effect of different ratio of raw materials on the crystal structure was investigated.X-ray diffraction and scanning electron microscopy were used to analyze the crystal and morpholo-gy of Li4 Ti5 O12 nanoplatelets.The analysis showed that the products were made up of Li4 Ti5 O12 nanoplatelets to form the flower-like microspheres with a spinel crystal structure.The constant charge-discharge experiments illustrated that the initial discharge capacity were up to 160,141,128mAh/g at the rate of 0.1,1,2C respective-ly.

以化学共沉淀法制备的球形Ni0.25Mn0.75CO3为前驱体合成高电压正极材料LiNi0.5Mn1.5O4,探讨用前驱体与Li2CO3直接反应和用前驱体分解后的氧化物与Li2CO3反应两种工艺路线对LiNi0.5Mn1.5O4形貌和电化学性能的影响。用扫描电镜(SEM)和X射线衍射(XRD)对Ni0.25Mn0.75CO3前驱体和LiNi0.5Mn1.5O4样品进行表征,用充放电测试和循环伏安法对LiNi0.5Mn1.5O4样品进行电化学性能研究。结果表明:两种方法合成的LiNi0.5Mn1.5O4均具有尖晶石型结构。但以前驱体Ni0.25Mn0.75CO3直接与Li2CO3反应合成的LiNi0.5Mn1.5O4的一次粒子颗粒较大,形貌较差,性能也较差;而以前驱体分解后的氧化物与Li2CO3反应合成的LiNi0.5Mn1.5O4的形貌及性能均较好。在3.0~4.9 V的电压范围内,1C倍率下电池的放电比容量达到136.3 mA.h/g,循环100次仍有126.5 mA.h/g,且材料具有较好的倍率性能;5C倍率下的首次放电比容量高达120.7 mA.h/g。

Spherical LiNi0.5Mn1.5O4 powder was synthesized from the coprecipitated Ni0.25Mn0.75CO3 precursor. The effects of two synthesis routes, Ni0.25Mn0.75CO3 precursor directly mixed with Li2CO3 and (Ni0.25Mn0.75)2O3 mixed with Li2CO3, on the morphology and electrochemical performance of LiNi0.5Mn1.5O4 cathode material were investigated. XRD, SEM, charge-discharge tests and cyclic voltammetry were utilized to characterize the properties of samples. The XRD results indicate that the LiNi0.5Mn1.5O4 samples synthesized from both methods exhibit spinel structure. The morphologies of the samples prepared from two routes are spherical. However, the LiNi0.5Mn1.5O4 sample synthesized directly from mixture of Ni0.25Mn0.75CO3 and Li2CO3 possesses larger primary particle size compared with the LiNi0.5Mn1.5O4 synthesized from the (Ni0.25Mn0.75)2O3 and Li2CO3. Besides, the latter LiNi0.5Mn1.5O4 shows more excellent electrochemical properties, delivers an initial discharge capacity 136.3 mA?h/g at the rat

采用反相微乳法，制备了TiO2/Li4 Ti5 O12/Na2 Ti6 O13复合催化剂，运用TG-DSC、XRD、SEM等分析方法对催化剂进行表征．在紫外光（λ＝365 nm）照射下，以2，4-二氯苯酚（2，4-DCP）作为目标污染物，用P-25型TiO2作对照，研究了 TiO2/Li4 Ti5 O12/Na2 Ti6 O13复合催化剂光催化降解2，4-DCP 的特性．结果表明，制备的TiO2/Li4 Ti5 O12/Na2 Ti6 O13复合催化剂成带状纳米结构，其长度大于5μm，宽度约60 nm，厚度小于30 nm，结晶良好，分散性高，在紫外光照射下，50 min内对20 mg·L-1的2，4-DCP降解率达到了99．8％，表现出了比P-25型TiO2更高的光催化活性．

TiO2/Li4Ti5O12/Na2Ti6O13 composite catalysts were synthesized by using reverse microemulsion method. Thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD) and scanning electron microscope ( SEM ) were employed to characterize the as-synthesized materials. The photocatalytic efficience of the as-prepared samples was tested by degradation of 2,4-dichlorphenol and compared with P25-TiO2 under ultraviolet irradiation (λ=365 nm ) . The results showed that the synthesized TiO2/Li4 Ti5 O12/Na2 Ti6 O13 composite catalysts had nanobelts structure with width over 60 nm, thickness of less than 30 nm and length up to 5 μm. It was demonstrated that the nanosized composite had good crystallization and high dispersion. It was also found that composite catalysts had higher photo-catalytic activity than P25-TiO2 for the degradation of 2, 4-DCP under ultraviolet irradiation. Nearly 99. 8% 2, 4-DCP with initial concentration of 20 mg·L-1 was degraded by the cat