非均匀沉淀法包覆合成LiNi0.9 Co0.07 Mn0.03O2锂离子正极材料

采用非均匀沉淀法包覆合成了LiNi0.9Co0.07Mn0.03O2锂离子正极材料.前驱体合成中各工艺条件与包覆材料的比表面积和电化学性能息息相关.试验研究了沉淀剂、搅拌速度、pH值和氨水浓度对包覆沉淀的影响及煅烧过程对材料电化学性能的影响.结果表明:在优化实验条件下Co/Mn复合包覆在β-Ni(OH)2表面上;正极LiNi0.9Co0.07Mn0.03O2首次放电容量为195mAh·g-1,50次循环后容量仍保持为188.6mAh·g-1.循环伏安研究表明:与LiNiO2相比,Co/Mn复合包覆合成正极材料LiNi0.9Co0.07Mn0.03O2的相变得到很好的抑制,材料显示出良好的循环性能.     

碳酸盐共沉淀法合成Li1＋xNi0.6Co0.2Mn0.2O2Fx正极材料及其电化学性能

采用碳酸盐共沉淀法合成Li1＋xNi0.6Co0.2Mn0.2O2Fx正极材料,研究了不同含量的Li、F复合掺杂对LiNi0.6Co0.2Mn0.2O2样品的晶型结构、形貌以及电化学性能的影响.研究结果表明：Li、F复合掺杂未改变LiNi0.6Co0.2Mn0.2O2样品的层状结构;掺杂后的样品颗粒细化;电化学循环性能和电极过程的可逆性明显得到提高.掺杂量x=0.06时,Li1＋xNi0.6Co0.2Mn0.2O2Fx样品的首次充放电容量分别为168,160 mA·h/g,循环50次后容量为153 mA·h/g.     

LiNi0.6Co0.1Mn0.3O2正极材料的合成与性能

采用共沉淀-高温固相法制备LiNi0.6Co0.1Mn0.3O2锂离子正极材料,并使用X 射线衍射仪（XRD）和扫描电镜（SEM）技术分别表征其结构和形貌.然后将所得LiNi0.6Co0.1Mn0.3O2正极材料组装成扣式电池,并表征其电化学性能,探讨烧结温度和锂配量对其电化学性能的影响.结果表明：所得LiNi0.6Co0.1Mn0.3O2正极材料的放电比容量随烧结温度的升高而增大,且在900℃时表现出最佳的电化学性能.室温下,1C倍率下,锂配量(n(Li)/n(Ni+ Co+ Mn)=1.09)时,正极材料的首次放电容量为143.7 mAh/g,50次循环后,正极材料的放电比容量仍有141.3 mAh/g,容量保持率为98.3%.     

包覆型锂离子正极材料LiNi0.9Mn0.03Co0.07O2的合成与性能

采用复合包覆法合成了锂离子正极材料LiNi0.9Mn0.03Co0.07O2,前驱体的合成过程条件与最终包覆的材料性能有关。讨论了包覆沉淀反应过程中沉淀剂、pH值、搅拌速度和氨水浓度对电化学性能的影响。同时还考察了煅烧制度对材料电化学性能的影响。结果表明：在优化条件下Co,Mn均匀包覆在β-Ni（OH）2表面上;合成的正极材料LiNi0.9Mn0.03Co0.07O2在电压范围3～4.3V,电流密度30mA·g^-1下,第二次放电容量为194mAh·g^-1,50次循环后容量仍保持为189mAh·g^-1,材料循环性能稳定。     

Al2O3包覆LiNi0.8Co0.2O2正极材料及其电化学性能

为了减少锂离子电池正极材料与电解液的相互作用,用沉淀法在LiNi0.8Co0.2O2表面包覆一层Al2O3,并通过电化学测试、扫描电镜和X射线衍射研究其表面形貌和晶体结构.结果表明,经过表面包覆后,有效地抑制了电解液对正极材料的侵蚀,虽然初始放电容量略有降低,但循环性能明显改善;Al2O3包覆量对LiNi0.8Co0.2O2电化学性能存在影响,包覆量为0.7%(质量分数)的样品性能最优.     

层状Ni-Mn基锂离子电池正极材料进展

层状Ni—Mn基锂离子电池正极材料具有层状结构镍酸锂(LiNiO2)的高比容量以及尖晶石型结构锰酸锂(LiMn2O4)的高安全性、低价格等特点，是最有可能代替或部分代替LiCoO2的新型正极材料用于小型锂离子电池，同时也可望用作低成本、高安全性和大容量动力型锂离子电池的正极材料。本文综述了层状Li—Ni—Mn—O系化合物和LiNi1/3Mn1／3Co1/3O2的合成工艺、结构特点和电化学性能，阐述了层状Ni—Mn基锂离子电池正极材料的发展、研究开发现状和应用前景。     

LiNi_(0.5)Mn_(0.5)O_2的合成及其AA电池电化学性能

采用共沉淀法合成LiNi0.5Mn0.5O2正极材料.采用X射线衍射(XRD)和扫描电镜(SEM)表征合成材料的结构和形貌.研究不同Li/(Mn+Ni)摩尔比、不同焙烧制度、不同化成制度对LiNi0.5Mn0.5O2的电化学性能的影响.结果表明,当Li/(Mn+Ni)摩尔比1.08、一次焙烧温度为500℃,二次焙烧温度为850℃下焙烧得到的材料电化学性能最佳.     

掺杂对正极材料LiNi0.8Co0.2O2电化学性能的影响

论述了近年来元素掺杂改善正极材料LiNi0.8 Co0.2 O2电化学性能的研究现状。对层状结构的稳定性与电化学性能的关系进行了分析，对不同的元素掺杂效果进行了比较。认为在优化合成条件的基础上，元素掺杂是提高锂离子电池正极材料电化学性能最有效的途径之一。     

LiNi0.5Mn0.5O2的合成及其AA电池电化学性能

采用共沉淀法合成LiNi0.5Mn0.5O2正极材料.采用X射线衍射（XRD）和扫描电镜（SEM）表征合成材料的结构和形貌.研究不同Li/（Mn＋Ni）摩尔比、不同焙烧制度、不同化成制度对LiNi0.5Mn0.5O2的电化学性能的影响.结果表明,当Li/（Mn＋Ni）摩尔比1.08、一次焙烧温度为500℃,二次焙烧温度为850℃下焙烧得到的材料电化学性能最佳.     

从工业废液中回收镍钴合成锂离子电池正极材料LiNixCo1—xO2

探索了从废液中回收钴在空气气氛下合成锂离子电池正极材料LiNixCo1-xO2的方法和工艺,结果表明,合成材料的充放电性能都比较好,LiNi0.3Co0.7O2在600℃6h→750℃16h时制得的产物初始充电容量达到154.938mAh/g,接近用分析纯的镍钴原料合成的正极材料LiNi0.3Co0.7O2的首次充电容量（156.146mAh/g）。     

镍钴酸锂的制备与电性能研究

以共沉淀法制得前驱体Ni0.8Co0.2(OH)2,再与LiOH.H2O混合通氧气于600℃恒温15h得到LiNi0.8Co0.2O2。X射线衍射分析表明合成的材料LiNi0.8Co0.2O2具有规整的-αNaFeO2层状结构。SEM表明材料颗粒呈类球体,大小均一。以0.1C电流充放电,首次放电比容量为176mA.h/g,循环20次后容量大幅度衰减。交流阻抗图谱表明材料充电态的电化学阻抗明显低于放电态的电化学阻抗。     

Influence of cobalt on performance of Cu-CeO_2 catalysts for preferential oxidation of CO

Copper and cobalt oxides supported on CeO_2 were investigated for preferential oxidation of carbon monoxide(CO-PROX) in the presence of excess hydrogen and CO_2.(Cuo)_(1-x)(Co_3 O_4)_(x/3)-(CeO_2)_(2.5)(x=0,0.25,0.50,0.75,0.85 and 1) catalysts were prepared by coprecipitation method.These mixed oxide catalysts were characterized by several physicochemical techniques,such as BET surface area(S_(BET)),X-ray diffraction(XRD),high resolution transmission electron microscopy(HRTEM),temperature programmed reduction(TPR) and X-ray photoelectron spectroscopy(XPS).XRD studies show the peaks related to CuO and Co_3 O_4 phases in copper and cobalt containing CeO_2 catalysts.The average particle size of the CeO_2 crystallites is in the range of 8-10 nm as evaluated from HRTEM studies.XPS studies demonstrate that Cu,Co and Ce in(cuO)_(1-x)(Co_3O_4)_(x/3)-(CeO_2)_(2.5) catalysts are presented in+2 and +1,+3 and +2 and +4 and +3 oxidation states,respectively.The catalyst with x=0.75 shows better activity and selectivity towards CO-PROX.Though the catalyst with only copper(CuO-CeO_2,x=0) shows good activity but reverse water gas shift(RWGS) reaction is noticed at high temperature.On the other hand,RWGS reaction is suppressed on the cobalt containing CuO-ceO_2 catalyst.Cobalt on CeO_2 with x=1 shows hardly any activity for PRoX reaction at low temperatures.No methanation activity is observed on CuO-CeO_2 or Co_3O_4-CeO_2 catalysts.In contrast,combination of copper and cobalt on CeO_2 shows methanation of CO where enhanced activity is observed with increasing in cobalt content.     

Novel 3D porous graphene decorated with Co_3O_4/CeO_2 for high performance supercapacitor power cell

Tremendous research efforts have been aimed at ever-increasing worldwide energy demand. For this purpose, the hybrid supercapacitor power cell were prepared composing 3D porous graphene decorated with Co_3O_4-CeO_2 nano-particles herein by using flower stem as biotemplate. The resulting samples were characterized by field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM), Raman spectra, X-ray diffraction spectroscopy(XRD), nitrogen adsorption and desorption, X-ray photoelectron spectrogram(XPS), and electrochemical test. The 3D graphene acted as an excellent carrier together with Co_3O_4-CeO_2 nano-particles, boosting the specific capacitance of composite(221 F/g), which exceeded the theoretical value limit. This facile biotemplate method of research provided an eco-friendly and cut-price route to obtain high-quality graphene and Co_3O_4-CeO_2nano-composites owing to the unique porous structure derived from original template(flower stem). The finding presented a simple strategy for fabrication of novel energy storage devices.     

Electrochemical synthesis,structure characterization and magnetic properties of Tb_xFe_7Co_3(x=0,0.6,0.8) nanowires

Highly ordered Tb_xFe_7 Co_3(x=0,0.6,0.8) nanowires were synthesized in alumina templates by electrochemical deposition method.Here,the effects of Tb content and annealing treatment on the phase composition,morphology,crystalline structure and magnetic properties were investigated.The asdeposited Tb_0 Fe_7 Co_3 nanowires comprise Fe_7 Co_3 phase.While after adding Tb,the diffraction peaks slightly shift left,indicating the infiltration of Tb atoms into Fe_7 Co_3 phase.After annealing,Tb_0 Fe_7 Co_3 nanowires still consist of Fe_7 Co_3 phase with a slight enhancement on coercivity.While the annealed nanowires with Tb doped present a complex phase composition containing Fe3 Tb,Fe_2 Tb,Co_3 Tb,Co_(17)Tb_2,TbFeO_3 and Fe_2 O_3 phases distribute in the central portion,and Co_(0.72)Fe_(0.28) at the nanowire outer walls.The annealed Tb_xFe_7 Co_3(x=0.6,0.8) nanowires show higher magnetic performance owing to the formation of hard magnetic phases,the interfacial elastic coupling between hard and soft phases and the coherent Fe3 Tb/Co_3 Tb interface which restrain the domain wall motion.To be specific,the coercivity and remanence ratio of TbxFe_7 Co_3(x=0.6,0.8) nanowires significantly enhance with increasing Tb content.     

Effect of praseodymium substitution for lanthanum on structure and properties of La0.65-xPrxNd0.12Mg0.23Ni3.4Al0.1（X=0.00-0.20） hydrogen storage alloys

In order to investigate the effect of substituting La with Pr on structural and hydrogen storage properties of La-Mg-Ni system (AB3.5-type) hydrogen storage alloys, a series of La0.65-xPrxNd0.12Mg0.23Ni3.4Al0.1(x=0, 0.10, 0.15, 0.2) hydrogen storage alloys were prepared. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) analyses revealed that two alloys (x=0.0 and 0.10) were composed of (La, Mg)2(Ni,Al)7 phase, La(Ni,Al)5 phase and (La,Mg)Ni2 phase, while other alloys (x=0.15 and 0.20) consisted of (La,Mg)2(Ni,Al)7 phase, La(Ni,Al)5 phase, (La,Mg)Ni2 phase and (La, Mg)(Ni,Al)3 phase. All alloys showed, however, only one pressure plateau in P-C isotherms. The Pr/La ratio in alloy composition influenced hydrogen storage capacity and kinetics properties. Elec-trochemical studies showed that the discharge capacity decreased from 360 mAh/g (x=0.00) to 335 mAh/g (x=0.20) as x increased. But the high-rate dischargeability (HRD) of alloy electrodes increased from 26% (x=0.00) to 56% (x=0.20) at a discharge current density of Id=1800 mA/g. Anode polarization measurements were done to further understand the electrochemical kinetics properties after Pr substitution.     

Catalytic oxidation of formaldehyde over CeO_2-Co_3O_4 catalysts

A series of CeO_2-Co_3O_4 mixed oxide catalysts with different Co/(Co+Ce) atomic ratios were synthesized by citric acid sol-gel method and used for catalytic oxidation of formaldehyde(HCHO). Many techniques such as Brumauer-Emmett-Teller(BET), X-ray diffraction(XRD), scanning electron microscopy(FE-SEM), temperature programmed reduction(H_2-TPR), temperature-programmed desorption(O_2-TPD) and X-ray photoelectron spectroscopy(XPS) were used to characterize catalysts. The results of catalytic performance tests showed that the catalyst CeO_2-Co_3O_4 with Co/(Co+Ce) ratio of 0.95 exhibited the best performance, and the temperature of complete oxidation of HCHO was 80 oC. The analytical results indicated that the addition of CeO_2 enhanced the specific surface area of Co_3O_4 and the fine dispersion of both of them. Moreover, the strong interaction between CeO_2 and Co_3O_4 resulted in the unique redox properties, which enhanced the available surface active oxygen and led to high valence state of cobalt oxide species. All those effects played crucial roles in the excellent performance of CeO_2-Co_3O_4 for the HCHO oxidation.     

Microstructure and electrochemical characteristics of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x（V0.81Fe0.19）x hydrogen storage alloys

Microstructure and electrochemical characteristics of La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x(V0.81Fe0.19)x hydrogen storage alloys were investigated. XRD indicated that La0.7Ce0.3Ni3.75Mn0.35Al0.15Cu0.75-x(V0.81Fe0.19)x alloys consisted of a single phase with CaCu5-type structure, and the lattice parameter a and cell volume V increased with increasing x value. The maximum discharge capacity first increased from 319.0 (x=0) to 324.0 mAh/g (x=0.05), and then decreased to 307.0 mAh/g (x=0.20). The high-rate dischargeability at the discharge current density of 1200 mA/g first increased from 52.1% (x=0) to 59.1% (x=0.15), and then decreased to 55.4% (x=0.20). The hydrogen diffusion in the bulky alloy was responsible for the high-rate dischargeability. Cycling stability first increased with increasing x from 0 to 0.10 and then decreased when x increased to 0.20, which was resulted from the synthesized effect of the improvement of the pulverization resistance and the decrease of corrosion resistance.     

Structural characterization and optical properties of long-lasting CaAl_2O_4:Eu~(2+),Nd~(3+) phosphors synthesized by microwave-assisted chemical co-precipitation

The present paper reported the structural and luminescent properties of Eu~(2+) and Nd~(3+) doped CaAl_2O_4 phosphor. The samples were prepared by microwave-assisted chemical co-precipitation(MA-CCP), a synthesis technique which is suitable for small and uniform particle that could be used directly without grinding. The effects of different microwave temperatures on structure and photoluminescence behavior were studied. Formation of a phosphor and phase purity were confirmed by X-ray diffraction technique(XRD) with variable microwave temperatures. XRD analysis showed that the phosphors prepared by MA-CCP method at the temperature of 750, 900oC, respectively and solid-state reaction(SSR) method at 1300oC consisted of impurities. Commission Internationale de L'Eclairage(CIE) color coordinates of CaAl_2O_4:Eu~(2+),Nd~(3+) were suitable as blue light emitting phosphor. Excitation and emission peaks of the samples prepared by different methods in this study were almost the same. The images of SEM showed that the size of the phosphors prepared by MA-CCP method reached a submicrometer.     

纳米La_2O_3粉晶的制备及其表征

以La(NO_3)_3·6H_2O、NH_4HCO_3和聚乙二醇为原料,利用沉淀法制备了纳米La_2O_3粉体,利用XRD,TG-DTA和TEM等测试方法对干凝胶热分解过程及最终形成的纳米La_2O_3粉体进行了分析和表征,XRD法考察了前驱体在不同热处理条件下产物物相和晶粒度的变化情况,实验结果表明,在适当工艺参数下,前驱体经720℃,1h焙烧所得产物为平均粒径小于50nm的La_2O_3粉体.     

Martensitic transformations in NiMnAl β phase alloys

Martensitic transformation characteristics in a wide range of alloy compositions in the NiMnAl system have been investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results indicate that while the NiMnAl alloys with relatively high Al and Mn contents transform martensitically to either the 14M(7R) or the 10M phase with a long-period stacking-order structure, those with low Al or Mn contents transform to the L1₀(3R:2M) structure. TheM _s temperature and thec/a ratio of the L1₀ martensite increase with decreasing Al or Mn content. In the Ni-30Mn-20Al alloy, typical premartensite microstructures, such as needlelike, modulated, and tweed structures, are observed and it is also found that a distorted B2 structure is formed as an intermediate phase prior to transformation to the 10M martensite.