复合掺杂纳米α-Ni(OH)2的制备与性能

采用微乳液法合成了铝、钴复合掺杂纳米Ni(OH)2粉体,并对其进行XRD、TEM、IR分析,结果表明:样品为α态的Ni(OH)2,平均粒径为40nm左右,同时发现样品的晶层间存在结晶水.将所制备的样品按一定比例与石墨、乙炔黑和镍粉混合均匀,以泡沫镍为集流体制成镍正极材料,并以贮氢合金片为负极进行电化学性能测试,结果表明:其比容量高达327.9 mAh/g,放电性能稳定,循环可逆性良好.     

Al(OH)3掺杂非晶态氢氧化镍的制备及其电化学性能

采用微乳液法合成了Al(OH)3掺杂非晶态Ni(OH)2粉体.研究了温度、pH值和掺杂剂的含量等各种因素对其电化学性能的影响并分析了其作用机理.实验表明样品制备的工艺条件为t=50℃、pH=12、 Al(OH)3掺杂含量为5%时,样品电极容易活化,循环性能较好.采用以100 mA/g恒电流充电4 h,以50 mA/g恒电流放电,终止电压为1.0 V的充放电制度,其比容量达346.1 mA·h/g,放电工作电位平稳于1.24 V.     

Co、Sr复合掺杂β-Ni(OH)2纳米粒子的制备及性能

用微乳液法制备了Co、Sr复合掺杂β-Ni(OH)2纳米粒子,详细研究了合成工艺条件对化学粒子结构形态与电化学性能的影响,探讨了掺杂纳米氢氧化镍电化学活性的作用机理.对样品分别进行了XRD、TEM分析,以及充放电性能和循环伏安特性的测试.结果表明,在pH=10.5、t=40℃,掺杂剂CoSO4、SrCl2的质量分数为3%、7%时,样品的平均粒径为35 nm左右,且分布较为均匀,无明显团聚现象.该条件下制备的样品以0.1C的倍率放电,在终止电位为1.0 V时,其比容量可达286.2 mAh/g,放电工作电位平稳于1.27 V.     

改变型混合教学模式下学习评价体系构建研究

改变型混合式教学模式是现阶段促进学习质量提升的最佳方式之一,合适的学习评价体系是有效实施该教学模式的核心要素之一。第四代教育评价理论、多元智能理论、建构主义学习理论为改变型混合学习评价体系的构建提供了理论依据,评价主体多元化、方式多样化、内容全面化、工具便捷化的评价原则再结合改变型混合式教学模式的基本流程,初步构建了改变型混合学习评价体系,该体系由评价类型、节点、指标、主体、方式、权重等要素构成。     

Synthesis and electrochemical properties of Cr-doped Li<Subscript>3</Subscript>V<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript> cathode materials for lithium-ion batteries

Cr-doped Li₃V₂(PO₄)₃ cathode materials Li₃V_2−x Cr _x (PO₄)₃ were prepared by a carbothermal reduction(CTR) process. The properties of the Cr-doped Li₃V₂(PO₄)₃ were investigated by X-ray diffraction (XRD), scanning electron microscopic (SEM), and electrochemical measurements. Results show that the Cr-doped Li₃V₂(PO₄)₃ has the same monoclinic structure as the undoped Li₃V₂(PO₄)₃, and the particle size of Cr-doped Li₃V₂(PO₄)₃ is smaller than that of the undoped Li₃V₂(PO₄)₃ and the smallest particle size is only about 1 μm. The Cr-doped Li₃V₂(PO₄)₃ samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram (CV), and electrochemical impedance spectra(EIS). The optimal doping content of Cr was that x=0.04 in the Li₃V_2−x Cr _x (PO₄)₃ samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Cr-doping. The improved electrochemical performances of the Cr-doped Li₃V₂(PO₄)₃ cathode materials are attributed to the addition of Cr³⁺ ion by stabilizing the monoclinic structure. Funded by the Guangxi Natural Science Foundation(No. 0832259) and the National Basic Research Program of China (No. 2007CB613607)     

两步固相碳包覆法合成Li_3V_2(PO_4)_3/C正极材料及其性能研究

以VPO_4/C为中间体,相继以乙炔黑及葡萄糖作为碳源,通过两步固相碳包覆法制备了纯相单斜晶系的Li_3V_2(PO_4)_3/C复合材料。该方法首先通过制备纳米级的VPO_4/C中间体,为后续制备Li_3V_2(PO_4)_3/C提高反应活性,降低热处理温度,其中碳源不仅起到还原剂、导电剂的作用,还能细化晶粒,且两步法包碳使得材料颗粒表面的碳层更均匀,从而改善材料的综合电化学性能。最终在750℃下煅烧12h得到颗粒细小且分布均匀的Li_3V_2(PO_4)_3/C样品,在电压区间3.0~4.5V内,该材料在0.1,1和2C倍率下的首次放电比容量分别为141.5,119.8和109.4mAh/g,在0.1C倍率下循环50次后的容量保持率高达97.7%。     

Synthesis and electrochemical properties of Ce-doped LiNi_（1/3）Mn_（1/3）Co_（1/3）O_2 cathode material for Li-ion batteries

The layered material of Ce-doped LiNi1/3Mn1/3Co1/3O2 with α-NaFeO2 was synthesized by a co-precipitation method. X-ray diffraction (XRD) showed that Ce-doped LiNi1/3Mn1/3Co1/3O2 had the same layered structure as the undoped LiNi1/3Mn1/3Co1/3O2. The scanning electron microscopy (SEM) images exhibited that the particle size of Ce-doped LiNi1/3Mn1/3Co1/3O2 was smaller than that of the undoped LiNi1/3Mn1/3Co1/3O2. The Ce-doped LiNi1/3Mn1/3Co1/3O2 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram (CV), and electrochemical impedance spectra (EIS). The optimal doping content of Ce was x=0.02 in the LiNi1/3-xMn1/3Co1/3CexO2 samples to achieve high discharge capacity and good cyclic stability. The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through Ce-doping. The improved electrochemical performances of the Ce-doped LiNi1/3Mn1/3Co1/3O2 cathode materials were attributed to the addition of Ce4+ ion by stabilizing the layer structure.     

带钢表面缺陷在线检测系统的设计

针对带钢表面缺陷人工检测方法效率低下的问题, 设计了一套在线自动检测系统.首先, 提出了带钢表面缺陷在线检测系统的总体设计方案, 包括系统的硬件结构、软件结构以及图像采集系统.随后, 着重研究了在线检测系统中所涉及的图像预处理方法、图像分割方法、特征提取选择和缺陷分类方法.通过缺陷区域频率域图像特征的提取和缺陷的人工神经网络分类, 提高了分类结果的准确性.最后, 采用常见缺陷的样本对该系统进行测试, 实验结果验证了算法的有效性.     

锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的合成及性能

采用氢氧化物共沉淀法合成了LiNi1/3Co1/3Mn1/3(OH)2前驱体,然后以Ni1/3Co1/3Mn1/3(OH)2和LiOH·H2O为原料,合成出了层状锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2.通过XRD、SEM和电化学测试对LiNi1/3-Co1/3Mn1/3O2材料的结构、形貌及电化学性能进行了测试和表征.结果表明,800℃烧结12h所合成的样品粒度大小分布比较均匀,该材料以0.2C充放电,其首次放电容量为150mAh·g-1,循环30次后容量为137mAh·g-1.