LiFePO4基正极材料容量的温度敏感特性及交流阻抗谱研究

采用原位碳包覆法制备了锂离子二次电池用LiFePO4／C复合正极材料。考察了环境温度对LiFePO4/C电池容量的影响，得到容量与绝对温度之间符合Arrhenius关系。运用交流阻抗谱分析了温度与电池电化学特性的关系，并对电极基于电荷和质量传递控制过程给出了一种新的模拟等效电路，通过Zview拟合软件得到了各个模拟元件的数值及变化趋势，从而定量地解释LiFePO4／C复合电极容量与温度的关系。     

LiFePO4/C锂离子电池正极材料的电化学性能

以碳凝胶作为碳添加剂,采用固相法制备了复合型LiFePO4/C锂离子电池正极材料.研究了不同掺碳量对样品性能的影响.利用X射线衍射仪、扫描电镜和碳硫(质量分数)分析方法对所得样品的晶体结构、表面形貌、含碳量进行分析研究.结果表明:样品中的碳含量(质量分数)分别为0%、5%、10%、22%,所得样品均为单一的橄榄石型晶体结构,碳的加入使LiFePO4颗粒粒径减小.另外,碳分散于晶体颗粒之间,增强了颗粒之间的导电性.合成样品的电化学性能测试结果表明,掺碳后的LiFePO4放电比容量和循环性能都得到显著改善.其中,含碳量为22%的LiFePO4/C在0.1 C倍率下放电,首次放电容量达143.4 mA·h/g,充放电循环6次后电容量为142.7 mA·h/g,容量仅衰减0.7%.     

LiFePO4／C复合正极材料的制备及其电化学性能研究

采用高温固相碳热还原法（CTR，Carbothermal Reduction）合成了LiFePO4／C复合正极材料。采用XRD，SEM以及BET等方法对产物进行表征。结果表明，所得LiFeP04／C材料有着单一的橄榄石型晶体结构。750℃下制备产物的BET比表面积为39．7002m^2／g。利用恒流充放电，循环伏安法（CV），电化学阻抗谱（EIS）等电化学手段研究了LiFePO4／C材料的电化学性质。结果表明：750℃下制备的LiFePO4／C复合材料在25℃工作温度下，有着优异的循环稳定性和大倍率充放电性能，使用850ma／g（5C）的电流密度对电池充放电90次后，电池放电比容量仍能保持11lmAh／g。在55℃工作温度下1C充放电倍率时，首次和第90次循环的放电比容量分别为14513mAh／g和142．9mAh／g。     

共沉淀法制备正极材料LiFePO4的研究

以氢氧化锂、硫酸亚铁铵和磷酸氢二铵为原料，研究了液相共沉淀法制备LiFePO4正极材料和掺杂Co^2＋的LiFePO4改性正极材料，并对其进行XRD、SEM分析和电化学性能测试。结果表明掺杂Co^2＋对正极材料的初始充电比容量为156．7mAh·g^-1，且循环60次后，容量仍有138．7mAh·g^-1，容量衰减率仅为11．4％。     

反应物中锂元素的量对LiFePO4/C电化学性能的影响

以Fe2O3和LiH2PO4为原料,葡萄糖为碳源,采用碳热还原法合成了LiFePO4/C正极材料,考察了反应物中锂元素的量对正极材料LiFePO4/C电化学性能的影响。用X射线衍射、扫描电镜(SEM)和恒电流充放电测试和循环伏安法对正极材料的结构、形貌以及电化学性能进行了研究。结果表明:当反应物中额外添加锂元素的量是理论量的10%时,制得的正极材料的电化学性能最佳,在0.2和1C(1C=170mA/g)的充放电倍率下,首次放电比容量分别为156.3和137.5mAh/g,经过20次充放电循环后,容量基本保持不变。     

共沉淀法制备正极材料LiFePO4的研究

以氢氧化锂、硫酸亚铁铵和磷酸氢二铵为原料,研究了液相共沉淀法制备LiFePO4正极材料和掺杂Co2+的LiFePO4改性正极材料,并对其进行XRD、SEM分析和电化学性能测试.结果表明掺杂Co2+对正极材料的初始充电比容量为156.7 mAh·g-1,且循环60次后,容量仍有138.7 mAh·g-1,容量衰减率仅为11.4%.     

1,2-丙二醇对锂离子电池正极材料LiFePO_4性能的影响

采用1,2-丙二醇作为表面活性剂,在水热反应中合成正极材料LiFePO4。用XRD、SEM、粒径分布测试和恒电流充放电方法,分别研究了1,2-丙二醇对LiFePO4的结构、形貌、粒径和电化学性能的影响。结果表明：加入适量的丙二醇不改变LiFePO4的橄榄石结构,但可使材料的结晶粒度变小,粒径分布变得均匀;当丙二醇加入量为10 mL时,得到的LiFePO4平均粒径d（0.5）=1.128μm,粒径分布范围为0.316~6.607μm;该材料在0.2C倍率下的首次放电比容量为144 mAh/g,循环性能良好。     

锂离子电池正极材料磷酸铁锂研究进展

电极材料是推进电池技术发展及应用的关键。作为锂离子电池正极材料的LiFePO4表现出优异的电池性能(大容量、优异循环特性),但也有本征低电导率的缺点。具有橄榄石结构的LiFePO4在电池充放电过程发生FePO4与LiFePO4之间的相变,已有实验证明充放电过程中出现固溶体LixFePO4。掺杂是提高材料电导率的常用手段,但LiFePO4的掺杂却一直饱受争议;缺陷化学的研究初步认定通过适当点缺陷的电荷补偿,晶体内引入掺杂元素是可以实现的,并且提出几种缺陷补偿机制。导电相复合可降低电极颗粒间的接触电阻,特别是LiFePO4的碳包覆有效地改善其电化学性能,促进其工业化推广;碳包覆的有效性取决于碳的sp2杂化键的比例及碳含量。由于电极材料形貌影响电池的充放电动力学过程,LiFePO4的颗粒尺寸、形状、表面粗糙度等的控制都成为提高电池性能的重要手段;LiFePO4的薄膜制备及三维构架技术则进一步推动微型电池的应用发展。     

一种新型的锂离子电池正极材料——LiFePO4

介绍了1种新型的锂离子电池正极活性材料LiFePO4并解释了材料的结构特征和电化学过程。LiFePO4具有较高的比容量和良好的循环稳定性等优良的电化学性能,但是目前还存在着制约容量释放的锂离子扩散系数小以及材料导电性能不太好等问题。在回顾该材料研究状态的基础上,说明了只要通过选取适当的制备工艺和进行合适的表面改性可以制备出具有优良电化学性能的LiFePO4粉体。这种粉体具有环境相容性、便宜以及资源丰富等诸多优点,是1种颇具潜力的锂离子电池正极替代材料。     

掺铝氧化锌包覆LiFePO4的合成与性能（英文）

以简单的固相法合成了橄榄石结构LiFePO4,并以导电掺铝氧化锌材料(AZO)对其表面进行包覆。充放电结果显示,表面包覆大幅度改善了LiFePO4材料的倍率和低温性能。在20C高倍率条件下,AZO包覆LiFePO4的放电比容量可达100.9mA·h/g;在低温20°C时进行0.2C充放电,未包覆LiFePO4和AZO包覆LiFePO4的放电比容量分别为50.3mA·h/g和119.4mA·h/g。经分析,这可能是由于采用导电AZO包覆措施而增加了LiFePO4材料的电导率,从而极大地提高了其比容量。另外,导电AZO包覆措施还增加了LiFePO4材料的振实密度。这些结果表明AZO包覆LiFePO4材料是一种很好的适用于锂离子动力电池的正极材料。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.