稀土掺杂对LiMn2O4电化学性能的影响

用固相反应法合成了具有尖晶石结构的可用作锂离子二次电池正极材料的锂锰氧化合物（LiMn2O4）,并对其进行了镧、铈、镨、钕、铕、钐等多种稀土元素的掺杂修饰,形成稀土复合氧化物（LixMn2-yRe7y/6O4,0.95≤x≤1.2,0≤y≤0.3）。对材料进行了X射线衍射、循环伏安、充放电等测试,实验结果表明,掺入镧、铕、钕、钐、镨等元素所合成的材料具有标准尖晶石结构,较好的电化学可逆性能,较优良的高温性能。该材料在EC:DMC（1:1）+1mol/L　LiPF6电解液中表现出了较优良的充放电性能,其首次放电容量达130mAh/g。     

在有机溶剂中电沉积Er-Co-Fe合金膜

利用循环伏安法和恒电位电解法研究了室温条件下在有机溶剂DMSO(二甲基亚砜)中Er-Co-Fe合金膜的电化学制备。实验结果表明:在0.1mol·L-1ErCl3-0.1mol·L-1FeCl2-0.1mol·L-1CoCl2-0.1mol·L-1LiClO4-DMSO体系中,当控制电位在-2.00V～-2.60V(vsSCE)范围内进行恒电位电解,可得到表面均匀、附着力强、有金属光泽的黑色非晶态Er-Co-Fe合金膜,其中铒的质量分数可达31.63%～43.15%。     

Effect of coke properties and its blending recipe on performances of carbon anode for aluminium electrolysis

The properties and blending recipe of petroleum cokes used to make high quality carbon anodes for aluminium electrolysis were studied. Three kinds of green cokes were selected for bench scale study to illustrate the effects of cokes properties and its blending recipe on anode performances. The results show that impurities derived mainly fi＇om cokes remarkably affect the CO2 reactivity and air reactivity of carbon anodes. Ca, Na and V can increase CO2 reactivity of calcined cokes but S has the contrary effect, and the cokes of high V level generally present high air reactivity. The anodes with good quality can be made by properly selecting and scientifically blending of cokes, some poor quality cokes can also be used to produce high quality anodes with a reasonable blending recipe. Na contaminated anodes have high CO2 reactivity and air reactivity, so the recycled anode butts should be well cleaned to reduce Na content before being introduced into anode production, which is especially important to the low S cokes.     

高精度超薄水晶片表面超声磨削机理的研究

高精度超薄水晶片的加工效率、表面损伤及翘曲变形等问题，一直是从事该方面研究和生产的难题之一。本文利用超声加工宏观磨削力、磨削应力、磨削热小，对加工材料表面损伤低的特点，再结合相关磨料对高精度超薄水晶片表面进行超声磨削加工。在工作机理研究的基础上，对超薄水晶片超声磨削进行了实验研究，优化了其工作参数，获得了满意的效果，为该技术的实际应用奠定了理论与实验基础。     

Preparation and properties of pitch carbon based supercapacitor

Using the mesophase pitch as precursor, KOH and CO2 as activated agents, the activated carbon electrode material was fabricated by physical-chemical combined activated technique for supercapacitor. The influence of activated process on the pore structure of activated carbon was analyzed and 14 F supercapacitor with working voltage of 2.5 V was prepared. The charge and discharge behaviors, the properties of cyclic voltammetry, specific capacitance, equivalent serials resistance (ESR), cycle properties, and temperature properties of prepared supercapacitor were examined. The cyclic voltammetry curve results indicate that the carbon based supercapacitor using the self-made activated carbon as electrode materials shows the desired capacitance properties. In 1 mol/L Et4NBF4/AN electrolyte, the capacitance and ESR of the supercapacitor are 14.7 F and 60 m?, respectively. The specific capacitance of activated carbon electrode materials is 99.6 F/g; its energy density can reach 2.96 W·h/kg under the large current discharge condition. There is no obvious capacitance decay that can be observed after 5000 cycles. The leakage current is below 0.2 mA after keeping the voltage at 2.5 V for 1 h. Meanwhile, the supercapacitor shows desired temperature property; it can be operated normally in the temperature ranging from -40 ℃ to 70 ℃.     

Electrical conductivity of Cu/（10NiO-NiFe2O4） cermet inert anode for aluminum electrolysis

Cu/(10NiO-NiFe2O4) cermets containing mass fractions of Cu of 5%, 10%, 15% and 20% were prepared, and their electrical conductivities were measured at different temperatures. The effects of temperature and content of metal Cu on the electrical conductivity were investigated especially. The results indicate that the metallic phase Cu distributes evenly in 10NiO-NiFe2O4 ceramic matrix. The mechanism of electrical conductivity of Cu/(10NiO-NiFe2O4) cermets obeys the rule of electrical mechanism of semiconductor, the electrical conductivity for cermet containing 5% Cu increases from 2.70 to 20.41 S/cm with temperature increasing from 200 to 900 ℃. The change trend of electrical conductivity with temperature is similar with each other and it increases with increasing temperature and content of metal Cu. At 960 ℃, the electrical conductivity of cermet increases from 2.88 to 82.65 S/cm with the content of metal Cu increasing from 0 to 20%.     

Effect of cooling modes on microstructure and electrochemical performance of LiFePO4

LiFePO4 was prepared by heating the pre-decomposed precursor mixtures sealed in vacuum quartz-tube. Three kinds of cooling modes including nature cooling, air quenching, and water quenching were applied to comparing the effects of cooling modes on the microstructure and electrochemical characteristics of the material. The results indicate that the water quenching mode can control overgrowth of the grain size of final product and improve its electrochemical performance compared with nature cooling mode and air quenching mode. The sample synthesized by using water quenching mode is of the highest reversible discharge specific capacity and the best cyclic electrochemical performance, demonstrating the first discharge capacity of 138.1 mA·h/g at 0.1C rate and the total loss of capacity of 3.11% after 20 cycles.     

超级电容器用活性炭的制备与电化学表征

以煤焦油沥青为前驱体,采用化学活化法制备了超级电容器用高比表面活性炭和活性炭电极.考察了活化温度对活性炭电极比电容量的影响,研究了活性炭材料的比表面积和孔结构与活性炭电极的充放电性能之间的关系,并对活性碳电极进行了电化学表征.结果表明,在500～700℃,随着活化温度的提高,活性炭电极的比电容量显著增大,当活化温度超过700℃时,活性炭电极材料的比电容量变化不明显.700℃活化温度下所制备的活性炭材料呈现明显的多孔结构,孔容为1.038cm3/g,比表面积为1959m2/g;所制成的活性炭电极比电容量为210F/g,等效内阻为0.9Ω/cm2,10mA/cm2充放电500次后保持90%以上电容量,交流阻抗谱在频率低于转化点时表现出纯粹的电容行为,循环伏安曲线显示出良好的可逆特性.     

中间相沥青粒径对活性炭材料及其电化学性能的影响

以煤焦油沥青为原料,在500℃下调制得到炭质微晶结构的中间相沥青.以不同粒径的中间相沥青为原料,以KOH和CO2为活化剂,采用物理-化学联合活化法制得超级电容器用高比表面积活性炭.以制备的活性炭作电极材料,以1 mol/L Et4NBF4/PC为有机电解液,考察活性炭材料的电容行为.结果表明:随着中间相沥青粒径的减小,活性炭比表面积先增大后减小;在中间相沥青粒径为150～250 μm时制备的活性炭的BET比表面积达最大值2 476 m2/g,质量比电容量最大,达到103.5 F/g.以粒径75～96 μm中间相沥青制备的活性炭表现出良好的功率特性,在1 mA充放电时,质量比电容量为87 F/g;在20 mA充放电时,质量比电容量也达到83 F/g.