Study of improved electrochemical performance of LiFePO4/C electrode for LIB

Lithium iron phosphate is a most promising cathode material for Li-ion batteries(LIB).But the key barrier limiting its application is extremely low electronic conductivity. Meanwhile the low electron conductivity can be improved by preparing LiFePO4 with carbon modified. LiFePO4/C was synthesized by high temperature solid-state reaction using iron (Ⅱ) oxalate, ammonium di-hydrogen phosphate and lithium carbonate with a kind of organic compound (CR) that can be dissolved in the dispersant (ethanol) as carbon sources added to the synthetic precursor in this paper.The samples were characterized by X-ray diffraction, scanning electron microscope observations,charge/discharge test, cyclic voltammetry and carbon analysis. It was believed that the synthesized LiFePO4/C with perfect olivine structure by X-ray diffraction. The carbon brought about two advantages: (i) an optimized particle size of LiFePO4, and (ii) increasing the electronic conductivity and Li+ diffusivity. The cathode material could demonstrate a charge/discharge flat voltage of 3.4V (Vs Li+/Li). Especially the active material with 20% organic added according to the final product of LiFePO4 showed very good electrochemical performance reaching about initial 162.0 mAh/g specific capacity at 0. 1C rate and could also keep excellent discharge capacity even at 3C rate (510 mA/g) current and good cycle performance. The carbon content in the final production was only 5.29%(mass fraction).     

Study of improved electrochemical performance of LiFePO_4/C electrode for LIB

1IntroductionThe ever-growing demand for portable batteries with high energy density is exerting pressure for thedevelopment of advanced Li-ion batteries.The remaining challenges are cost,abuse tolerance,and low-temperature performance.One critical challenge is the thermal stability of the battery components.Pres-ently LiFePO4with a structure of olivine-type,first published by Goodenough[1],has become more con-cerned because of its high energy density,low raw materials cost,environmental fr…     

IrO2·Ta2O5涂层钛电极电化学性能的研究

与PbAg电极、RuTi涂层电极相比,IrTa涂层钛电极析氧电极电位较低,电催化活性高.测量析氧电极电位时,用汞-硫酸亚汞电极(MSE)作参比电极,可避免溶液不同带来的测量误差.IrTa涂层钛电极适合在较高槽电压下电解运转.     

水热法制备锂离子电池正极材料LiFePO4及其性能研究

以H3PO4,FeSO4·7H2O和LiOH·H2O为原料,采用水热法制备锂离子电池正极材料LiFePO4,并以葡萄糖为碳源对其进行碳包覆.考查了pH值、水热反应温度和反应时间等工艺条件对合成产物的结构、微观形貌和电化学性能的影响.结果表明,pH值对水热反应合成LiFePO4有很大的影响,当前驱体pH值为7左右时能得到较纯的LiFePO4.260℃水热反应4 h所合成的LiFePO4碳包覆后的电性能最好,0.1C倍率下首次充放电比容量分别为152和146 mAh/g.     

水热法合成纳米LiFePO_4/石墨烯复合材料的组织结构及其光学特性

采用溶剂热法制备了纳米磷酸铁锂及磷酸铁锂/石墨烯复合材料,研究了不同溶剂及石墨烯含量对纳米磷酸铁锂组织结构及其光学性能的影响。结果表明,以体积比为19∶1的乙二醇水溶液作溶剂所制备的纳米磷酸铁锂结晶良好,颗粒细小且粒径分布均匀。透射光谱分析表明,石墨烯的复合降低了近红光的透过率。磷酸铁锂的光学带隙与纳米材料的晶粒大小及石墨烯含量有关。     

锂动力电池LiFePO4电极的加速寿命

采用LiFePO4商业电池的正电极组装成扣式电池,以温度和放电倍率为加速因子进行加速寿命循环试验.结果表明,寿命循环前期的扣式电池,容量和功率均出现先增加后衰减的变化规律.高温加速了电化学过程,但对锂离子扩散系数影响不大.大倍率放电,使电极的极化加强,加速了电池老化.     

动力型锂离子电池正极材料LiFePO4的产业化进展

从磷酸铁锂国内外主要厂商及其产能、国内外市场状况、产业化技术路线和产业化面临的问题及产业风险等几个方面综述了磷酸铁锂材料近年来在产业化方面的最新进展。介绍了LiFePO4产业化合成方法及其优缺点,并提出了磷酸铁锂电池材料产业化急需解决的问题。     

矿用电机车磷酸铁锂蓄电池在线状态检测系统

矿用电机车磷酸铁锂蓄电池的工作状态参数主要包括单体电池的工作电压、电流和温度。分别采用独立的模块对这3个量进行在线检测。电压检测部分再采用整体分布、部分集中的思路:将串联电池分成若干组,每组由电压检测模块集中检测。电压、电流和温度检测的模块化提高了检测系统的灵活性。通过试验验证该方法检测的数据准确。     

微正压ICVI制备C／C复合材料的工艺探索

研究了反应气体浓度对微正压等温化学气相沉积制备的C／C复合材料密度和显微结构的影响，结果表明：在微正压和900℃的沉积条件下，用丙烯作为碳源、针刺毡作为预制体，氮气与丙烯的气体流量比为25：1，经过105h沉积后，C／C复合材料的密度达到1．52g／cm^3；通过偏光显微镜观察分析发现试样外部除了围绕在炭纤维周围的光滑层外，还沉积了大量的再生结构热解炭，试样内部主要以光滑层结构为主．图7，参12．     

QEMSCAN analysis as a tool for improved understanding of gravity separator performance

QEMSCAN analysis of the feed and products to a gravity concentrator can provide a detailed understanding of the effect of mineralogy, particle size and liberation on separator performance. The use of particle categorisers in Intellection’s iExplorer software allows particles to be classed by calculated density and size. Mineral, or elemental, recovery data by size can then be determined for a given set of operating conditions much more easily than by using conventional heavy liquid analysis. The procedure has been demonstrated successfully for the Mozley laboratory mineral separator using a chromite ore.QEMSCAN analysis has been shown to readily provide separator performance as a function of particle size and density. This information was used to model the performance of the separator. The model was tested against a second independent ore giving encouraging results when used for prediction of the recovery/grade relationship. The potential for using this technique to predict industrial separator performance from feed mineralogy is discussed.     

C-SiC-B_4C复合材料烧结曲线的制定研究

利用TG-DSC热分析和傅里叶红外光谱分析研究了在不同炭化温度下C-SiC-B4C复合材料用煤沥青粘结剂的热缩聚焦化过程,考察了煤沥青焦化过程中内部结构基团变化。通过对中温煤沥青的TG-DSC分析和红外分析结果发现:中温煤沥青的结焦炭化过程主要在210~600℃之间完成,当利用煤沥青作粘结剂制备C-SiC-B4C复合材料时,这个温度区间的升温速率必须尽量减慢;一定范围内,随着烧结温度的提高,能够提高C-SiC-B4C复合材料的致密化程度。     

B_4C含量对Ni-Co/B_4C复合镀层硬度及耐磨性的影响

采用复合电沉积的方法制备出Ni-Co/B4C复合镀层。利用光学显微镜、XRD衍射等方法分析了复合镀层的微观形貌及相结构。结果表明,所制备的Ni-Co/B4C复合镀层均匀致密,基体界面结合良好,B4C颗粒分布均匀,镀态下镀层为晶态结构。研究了镀液中B4C颗粒含量对复合镀层硬度及耐磨性的影响,随着镀液中B4C颗粒含量的增加,Ni-Co/B4C复合镀层的显微硬度和耐磨性能均明显提高。     

锂离子电池负极材料LiFeTiO_4/C的制备及其电化学性能

以Li_2CO_3、Fe_2O_3和TiO_2为原料,葡萄糖为碳源,采用高温固相法合成了锂离子电池LiFeTiO_4/C复合材料。采用X射线衍射(XRD)、傅里叶红外光谱(FTIR)、透射电子显微镜(TEM)等手段对材料的晶体结构和形貌进行了表征,通过恒流充放电、循环伏安(CV)和交流阻抗对材料的电化学性能进行了测试。结果表明,碳包覆后的LiFeTiO_4负极材料循环性能优于未经碳包覆的材料。在室温下,充放电倍率为0.5C时,LiFeTiO_4/C负极材料的首次放电比容量为327.8 m Ah/g,循环50周后仍保持在308.3 m Ah/g。     

MLCC电极用超细铜粉的制备及其形貌研究

以CuSO4为原料，对用NaOH沉淀一葡萄糖预还原一水合肼还原工艺制备的超细铜粉进行了研究．结果表明：葡萄糖预还原和分步添加水合肼均有利于超细铜粒子的均匀生长，加入适量的PVP有助于超细铜粉颗粒均匀和球形度更高．用该工艺可制得粒度均匀且可控、分散性好的MLCC电极用球形超细铜粉．     

钛基pH电极表面离子轰击处理的研究

采用离子轰击技术对钛基ｐＨ电极进行表面处理,在其表面生成以δ相和ε相为主的组织结构。离子氮化后再引入微量氧可使渗层结构中有部分氧化钛,对ｐＨ的响应好。经该工艺处理的钛基ｐＨ电极与玻璃ｐＨ电极测量ｐＨ的结果一致,而且克服了玻璃ｐＨ电极容易破碎的缺点。采用本工艺可生产性能优良的ｐＨ传感器。     

基于C/S模式的煤炭资源管理系统研究

煤炭是中国最主要、最重要的能源,而煤炭又是一种不可再生资源。然而,多年来落后的生产和管理模式使得中国煤炭资源行业及其它企业一直是以高消耗、高污染、高浪费来支撑国民经济的发展。为了提高煤炭资源管理效率和水平,文章研究了基于C/S模式的煤炭资源管理系统。文章的研究对于推动中国煤炭资源管理的改革具有积极的意义。     

基于C／S的矿山测量数据库管理信息系统的研究

文中详细阐述了Client/Server的基本结构,并论述了矿山测量数据库管理信息系统建立的方法,着重介绍了系统设计、功能和特点。     

Comparison of the electrochemical mechanism of chalcopyrite dissolution in the absence or presence of Sulfolobus metallicus at 70 °C

The electrochemical mechanisms of chalcopyrite dissolution in the absence and presence of Sulfolobus metallicus at 70 °C were studied using cyclic voltammetry and Tafel methods. The cyclic voltammetry experiments show that S. metallicus does not change the oxidative and reductive mechanisms of chalcopyrite dissolution. The initial oxidation potentials of chalcopyrite dissolution are equal in the absence and presence of S. metallicus. However, the current density of oxidation in the presence of S. metallicus increases significantly. At about 0 V, the products on the surface of chalcopyrite are CuS, elemental S⁰, and Fe²⁺. At about 0.384 V, CuS may be oxidized, and chalcopyrite may be transferred to CuO, Fe₂O₃, and elemental S⁰. The Tafel experiments show that S. metallicus may increase the corrosion potential and corrosion current density of chalcopyrite. S. metallicus may also reduce the polarization resistance of chalcopyrite in bioleaching. These results indicate that S. metallicus may accelerate the oxidation of chalcopyrite.     

印刷电路板酸性蚀刻废液回收工艺中电极反应过程动力学研究

在印刷电路板酸性蚀刻废液中选用Ir系和Ru系电极作阳极,通过稳态动电位扫描和循环伏安扫描,对电极表面发生析氯和电积铜反应过程动力学进行了研究.在0.5 mol/L H_2SO_4溶液中及20kA/m~2电流密度下,Ir系钛阳极的强化使用寿命为Ru系钛阳极的20倍.Ir系钛阳极的析氯电位比Ru系钛阳极高,两种电极的析氯反应都属于不可逆反应.     

Utilization of electrochemical impedance spectroscopy for monitoring bornite (Cu5FeS4) oxidation by Acidithiobacillus ferrooxidans

In this work, the monitoring of the bacterial and chemical dissolution of bornite was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS); the mineral surface was examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The analysis of CV results allowed attributing the different peaks observed in both direct and reverse potential scanning to the oxidation of bornite to a secondary covellite and its reduction via different non stoichiometric copper sulphides intermediaries. EIS data for bornite were obtained in control medium up to 78 h of immersion, when a cellular suspension of A. ferrooxidans was added and the experiments continued up to a 192 h of test. The EIS response was different when bacteria were added in the beginning of the test or after some hours of immersion in acid solution. The experiments were performed in different cell configurations and a model of the electrode/electrolyte interface. The correspondent equivalent electrical circuit was used to fit impedance spectra for all studied conditions. A common equivalent circuit used for corrosion processes where anodic (degradation of the mineral) and cathodic (oxygen reduction) reactions occur in parallel, together film and biofilm formation was proposed.