锂离子蓄电池正极材料LiMn2O4--包覆LiCoO2对LiMn2O4循环性能的影响

将LiMn2O4置于LiAc和CoAc2的混合溶液中,缓慢蒸干溶液,煅烧后获得了包覆LiCoO2的LiMn2O4材料。通过电化学测试研究了钴的包覆量、煅烧温度、煅烧时间对包覆LiCoO2的LiMn2O4材料循环性能的影响,并比较了包覆Li CoO2前后,LiMn2O4材料分别在常温和高温环境下循环性能的差异。实验结果表明,在LiMn2O4的表面包覆LiCoO2,可以使LiMn2O4在常温和高温环境下获得良好的循环性能。     

Al_2O_3包覆LiCoO_2对4.35V锂离子电池性能的影响

用固相法对钴酸锂(LiCoO2)正极材料进行纳米三氧化二铝(Al2O3)表面包覆,在充电终止电压为4.35 V时分析制备的495060AR型锂离子电池的性能。在放电截止电压为3.00 V时,以0.5 C放电,包覆、未包覆LiCoO2的比容量分别为167.6 mAh/g、170.9 mAh/g,平均电压分别为3.763 V、3.776 V;常温下1.0 C循环200次,包覆、未包覆LiCoO2的容量保持率分别为94.46%、96.40%。在55℃、48 h储存测试中,包覆LiCoO2制备的电池表现出更好的环境适应性;包覆LiCoO2制备的电池在高温45℃下以0.5 C循环200次,容量保持率为93.50%。对电池进行过充、热冲击测试,均未起火、爆炸。     

LiCoO2表面原位包覆AlPO4及性能研究

采用AlPO4对LiCoO2进行了表面原位包覆,并通过扫描电子显微镜法(SEM)、透射电子显微镜法(TEM)、X射线衍射光谱法(XRD)及电化学性能测试等分析手段比较了未包覆和包覆后材料的性能.结果表明AlPO4包覆层均匀,厚度为20 nm左右;包覆后LiCoO2的循环性能得到显著改善.     

In situ-coating LiCoO2 with A1PO4 and its performance

采用AlPO4对LiCoO2进行了表面原位包覆,并通过扫描电子显微镜法(SEM)、透射电子显微镜法(TEM)、X射线衍射光谱法(XRD)及电化学性能测试等分析手段比较了未包覆和包覆后材料的性能.结果表明AlPO4包覆层均匀,厚度为20 nm左右;包覆后LiCoO2的循环性能得到显著改善.     

正极材料Li2MSiO4(M=Fe、Mn)的研究进展

对近年来有关正极材料Li2MSiO4(M=Fe、Mn)的结构特征、电化学性能中存在的问题(如电导率低、容量衰减等)及性能改善的方法(如掺杂、包覆等)进行了综述.总结了对结构认识存在分歧的原因及合成方法对材料性能的影响.     

LiCoO2的TiO2包覆原理探索研究

文献中对LiCoO2材料的表面包覆已经进行大量的报道,清晰显示LiCoO2的表面改性对材料循环性能产生了重要正性效应。然而,材料的包覆原理和作用机制直到目前仍然模糊不清,没有一个确定统一定论。采用溶胶-凝胶法,结合TiO2与LiCoO2体相反应的研究结果,详细地研究了TiO2对LiCoO2的包覆效应,建议了可能包覆原理和作用机制。     

用废旧锂离子电池回收的钴制备LiCoO2

用废旧锂离子电池回收的钴,通过草酸铵[(NH4)2C2O4]沉淀-固相法制备钴酸锂(LiCoO2),考察了(NH2)2C2O4用量、沉淀反应温度及时间等的影响,最优条件为:n(C2O42-):n(Co2+)=1.15:1.00,在40～50℃下沉淀10 min,相应的钴回收率为99.2%.将CoC2O4和过量5%的Li...     

Li[Li_(0.2)Mn_(0.54)Ni_(0.13)Co_(0.13)]O_2/BiPO_4的高循环性能

用固相法合成富锂材料Li[Li0.2Mn0.54Ni0.13Co0.13]O2,通过包覆磷酸铋(Bi PO4)对材料进行表面改性,以提高循环稳定性。XRD、SEM及TEM测试结果表明,包覆材料Li[Li0.2Mn0.54Ni0.13Co0.13]O2/Bi PO4的结构与Li[Li0.2Mn0.54Ni0.13Co0.13]O2相比没有发生变化,Bi PO4均匀地包覆在材料表面,包覆层厚度约为10 nm。在2.0~4.8 V充放电,当电流为0.1 C时,制备的Li[Li0.2Mn0.54Ni0.13Co0.13]O2/Bi PO4的首次库仑效率从Li[Li0.2Mn0.54Ni0.13Co0.13]O2的75%提高到83%,以0.2 C循环100次,放电比容量保持在249 m Ah/g。     

锂离子电池正极材料硅酸亚铁锂的研究现状

介绍了锂离子电池正极材料硅酸亚铁锂(Li2FeSiO4)的结构及充放电特性,评述了合成Li2FeSiO4的方法,包括高温固相法、溶胶-凝胶法、微波法、水热法和水热辅助溶胶-凝胶法等.介绍了提高Li2FeSiO4电化学性能的研究,包括碳包覆、金属离子掺杂、形貌控制和高于1个Li+脱嵌的研究等.反应机理及实现高于1个Li+...     

α-LiAlO2包覆Li[Li0.2Mn0.54Co0.13Ni0.13]O2的性能

用共沉淀法制备了固溶体正极材料Li[Li0.2Mn0.54Co0.13Ni0.13]O2,并用偏铝酸锂(α-LiAlO2)进行包覆改性.XRD和场发射扫描电子显微镜(FESEM)测试表明:包覆前后的材料均属于α-NaFeO2六方层状结构,R3m空间群;包覆后的样品颗粒表面形成了一层不均匀絮状包覆物α-LiAlO2.包覆量为3％的样品性能较好:以低电流(0.05 C)在2.0～4.8 V循环,首次放电比容量达273.0 mAh/g;当电流提高到1.00C时,放电比容量为173.2 mAh/g.倍率性能的提高,得益于包覆样品具有的较低的界面电阻与反应电阻,电化学阻抗谱(EIS)测试结果证明了这一点.     

氢氧等离子体合成过氧化氢过程的能效研究

为提高氢氧等离子体合成H2O2技术的能量效率,通过分析放电过程的反应器能效及电源能量注入效率,确定了影响合成总能效的主要因素。考察了反应器电极间距、电源放电频率及注入功率对反应器能效和电源能量注入效率的影响。发现减小电极间距、提高放电频率和注入功率有利于提高反应器能效,但不利于提高电源能量注入效率。本研究中可以得到150 gH2O2/kWh的反应器能效,但由于较低的电源能量注入效率,致使合成H2O2的总能效不超过9 gH2O2/kWh。因此,提高等离子体法合成H2O2过程的总能效,不仅需要设计高能效的等离子体反应器,还需为反应器负载开发适配的电源,而后者是提升该技术能量效率的关键。     

Electron-Ion Transport in ZrO2-Y2O3-CeO2 Ceramics

Simultaneous conduction of oxide ions and electrons in solid ceramic systems provides the capability for oxygen transport under a concentration gradient without the need for an externally applied electric field. In the present study, ionic transference numbers have been measured in the ZrO₂-5.8%Y₂O₃-10%CeO₂ system by open circuit Emf measurements involving different metal/metal oxide electrodes. In order to correlate the ionic transference number with grain size, high-density ceramic discs of different grain sizes (50 nm–5 m) were prepared by sintering pressed powders at various temperatures and times. Hydrothermal synthesis was used to prepare nanocrystalline powders of the above material with uniform crystallite size (10 nm) and chemistry. Emf measurements on the samples suggested both ionic and electronic transport, the ionic transference number decreasing with increase in the grain size. This observation was attributed to an increase in the amount of continuous crystalline grain boundary phase in the ceramics as the grain size increased. The presence of crystalline silicate and zirconate phases in the grain boundary region was confirmed by electron microscopic imaging combined with microanalysis. In the large grain (5 m) ceramics, the ionic transference number decreased linearly with temperature. As the grain size decreased, a maximum occurred in the ionic transference number vs. temperature curve. This maximum became more pronounced at smaller grain sizes. Better grain-grain contact and the doping effect of trivalent Ce in the grain boundary core are proposed to explain this observation.     

RuO_2-IrO_2-TiO_2析氧催化剂的制备工艺

以Ti N、RuCl3和H2IrCl6为原料,用真空浸渍-热分解法制备了RuO2-IrO2-Ti O2,研究了煅烧温度和n(Ru+Ir)∶n(Ti)对产物的影响。XRD分析表明:Ti N在高温煅烧时氧化生成金红石型Ti O2,RuO2、IrO2和Ti O2以固溶体的形式存在。CV、阳极极化曲线和EIS测试表明:RuO2-IrO2-Ti O2的最佳煅烧温度为400℃,随着n(Ru+Ir)∶n(Ti)的提高,催化剂的活性增强;在相同电位下,RuO2-IrO2-Ti O2的电流密度大于IrO2,可用作固体聚合物电解质(SPE)水电解催化剂。     

富氧火焰原子吸收光谱法测定铅钙锡合金中的锡

采用富氧火焰 (Air—C2 H2 —O2 )原子吸收光谱法直接测定铅钙锡合金中 0 1%以上的锡。对仪器工作条件、测定体系酸度、共存离子干扰等作了研究。方法准确度高 ,结果重现性好     

Thermoelectricity of p-Fe2O3-SO3-SiO2-others and n-Fe2O3-SiO2-CuO-others

Thermoelectric minerals have been found at Loei Province, in the northeastern part of Thailand. Local mineral specimens were prepared in the powders and bulk solids form by crushing, calcination and annealing, pressure and sintering, cutting and polishing. Mineral samples were used to analyze the composition and phase, determine the thermoelectric property and efficiency, design and construct a thermoelectric generator. Chemical composition and phase identification of powder samples were analyzed by the x-ray fluorescence (XRF) and x-ray diffraction (XRD), respectively. XRF and XRD results indicated that the mineral samples comprised the SO₃-CaO-SiO₂-others, Fe₂O₃-SO₃-SiO₂-others, Fe₂O₃-SiO₂-others and Fe₂O₃-SiO₂-CuO-others. From the thermoelectric property and efficiency determinations, the p-SO₃-CaO-SiO₂-others, p-Fe₂O₃-SO₃-SiO₂-others, n-Fe₂O₃-SiO₂-others and n-Fe₂O₃-SiO₂-CuO-others bulks were found to exhibit the thermoelectric figure of merit in orders of 10^?14, 10^?11, 10^?14 and 10^?13 K^?1, respectively. A fabricated thermoelectric generator made from ten pairs of p-Fe₂O₃-SO₃-SiO₂-others and n-Fe₂O₃-SiO₂-CuO-others legs that can be provided the open circuit voltage and short circuit current up to 48.30 mV and 0.14 μA for a temperature difference of 39.80 K at room temperature, respectively. While the internal resistance decreased and reached a value of 665 kΩ.     

Mixed Hydroxide Precursors for La2Ti2O7 and Nd2Ti2O7 by Homogeneous Precipitation

Feasibility of formation of stoichiometric precursors of either M₂ (TiO)₂(C₂O₄)₅ 4H₂O (M = La and Nd) or coprecipitated hydroxides of M(OH)₃+TiO(OH)₂ was investigated by two solution routes at different pH values. Composition of precipitates obtained at pH = 7.0 by coprecipitation method starting from La or Nd nitrates and potassium titanyl oxalate corresponded to a physical mixture of La or Nd(C₂O₄)₃ 9.5H₂O and TiO(OH)₂7·H₂O which on thermal decomposition did not yield phase pure M₂Ti₂O₇. However, precipitation from La or Nd nitrates and titanium tertrachloride by urea hydrolysis yielded homogeneous mixture of hydroxides of La or Nd and Ti, which on pyrolysis at 950°C yielded phase pure La₂Ti₂O₇ and Nd₂Ti₂O₇. Use of potassium titanyl oxalate as precursor for Ti, led to selective precipitation of La or Nd oxalate even at pH as low as 0.1 leading to sequential precipitation of La or Nd oxalate followed by Ti hydroxide at pH = 3.0. The resultant precipitate on pyrolysis underwent typical solid-state reaction.     

pH-MnO_2电极电位与MnO_2活性

本文对用于电池的MnO_2进行电化学评价,测定不同产地锰矿的pH—电极电位关系,每个样品的模拟制作,锌—锰干电池并测定共放电容量,通过比较放电容量和MnO_2的电极电位,从而对MnO_2进行活性评价。     

过氧化氢钝化工艺的改进

传统的过氧化氢钝化工艺较难掌握，钝化条件比较苛刻，钝化效果一般，还容易出现一种褐色不明附着物。经过大量试验研究，对过氧化氢钝化工艺进行了改进，钝化效果明显提高。     

Dielectric and Piezoelectric Properties of Nonstoichiometric SrBi2Ta2O9 and SrBi2Nb2O9 Ceramics

Nonstoichiometric SrBi₂Ta₂O₉ (SBT) and SrBi₂Nb₂O₉ (SBN) ceramics were prepared by a solid state reaction method. X-ray diffraction analysis showed that single-phase of Bi-layered perovskite was obtained. With different Sr/Bi content ratios of SBT and SBN, Curie temperature (T_C), electromechanical factor (K_p) and mechanical quality factor (Q_m) were measured. T_C of SBN (SBT) rose from 414C (314C) to 494C (426C) when Sr/Bi content ratio was increased from 0.55/2.3 to 1.2/1.8. In the most Sr-deficient/Bi-excess ratio of 0.55/2.3, the maximum values of Q_m were obtained approximately 1013 and 3325 for SBT and SBN, respectively.