Mg2+掺杂对正极材料LiFePO4/C结构和电化学性能的影响          下载免费PDF全文

王丽娜 《盐湖研究》2011,19(4):53-57,72

以乙酸镁为镁源,用LiOH.H2O、Fe(NO3)3.9H2O、NH4H2PO4为原料通过水溶液法制备了掺杂Mg2+的LiFePO4/C正极材料。用XRD、SEM、恒流充放电测试、循环伏安(CV)和交流阻抗谱(EIS)方法,研究了Mg2+掺杂对LiFePO4/C的结构、形貌及电化学性能的影响。研究结果表明,Mg2+掺杂没有改变LiFePO4橄榄石型的结构;在0.1 C(1C=170 mAh.g-1)的充放电倍率下,Mg2+掺杂使正极材料首次放电比容量从153 mAh.g-1提高到159 mAh.g-1,经20循环次后,容量无损失;电化学交流阻抗显示,掺杂后材料阻抗Rct从463.1Ω减小到322.8Ω。  相似文献   

大量Li+存在对Mg2+分析测定的影响研究   总被引：5，自引：1，他引：5       下载免费PDF全文

王士强  高洁  余学  张宝军  孙柏  邓天龙 《盐湖研究》2007,15(1):44-48

在含锂盐湖卤水体系中,大量Li+的存在,对络合滴定法测定Mg2+易产生较大的干扰,使分析结果偏高。根据盐湖卤水体系中锂盐的含量,通过调整正丁醇和无水乙醇混合液的加入量可很好地抑制Li+的干扰,从而保证Mg2+分析结果的相对误差不超过0.3%。  相似文献   

A thermodynamic model of high temperature lava vaporization on Io     

Laura Schaefer 《Icarus》2004,169(1):216-241

We modified the MAGMA chemical equilibrium code developed by Fegley and Cameron (1987, Earth Planet. Sci. Lett. 82, 207-222) and used it to model vaporization of high temperature silicate lavas on Io. The MAGMA code computes chemical equilibria in a melt, between melt and its equilibrium vapor, and in the gas phase. The good agreement of MAGMA code results with experimental data and with other computer codes is demonstrated. The temperature-dependent pressure and composition of vapor in equilibrium with lava is calculated from 1700 to 2400 K for 109 different silicate lavas in the ONaKFeSiMgCaAlTi system. Results for five lavas (tholeiitic basalt, alkali basalt, Barberton komatiite, dunite, and a molten type B1 Ca, Al-rich inclusion) are discussed in detail. The effects of continuous fractional vaporization on chemistry of these lavas and their equilibrium vapor are presented. The predicted abundances (relative to Na) of K, Fe, Si, Al, Ca, and Ti in the vapor equilibrated with lavas at 1900 K are lower than published upper limits for Io's atmosphere (which do not include Mg). We predict evaporative loss of alkalis, Fe, and Si during volcanic eruptions. Sodium is more volatile than K, and the Na/K ratio in the gas is decreased by fractional vaporization. This process can match Io's atmospheric Na/K ratio of 10±3 reported by Brown (2001, Icarus 151, 190-195). Silicon monoxide is an abundant species in the vapor above lavas. Spectroscopic searches are recommended for SiO at IR and mm wavelengths. Reactions of metallic vapors with S- and Cl-bearing volcanic gases may form other unusual gases including MgCl₂, MgS, MgCl, FeCl₂, FeS, FeCl, and SiS.  相似文献   

Magnesium recovery from magnesite tailings by acid leaching and production of magnesium chloride hexahydrate from leaching solution by evaporation     

Mine zdemir  Dilek ak&#x;r  &#x;lker K&#x;pak 《International Journal of Mineral Processing》2009,93(2):209-212

The recovery of magnesium from magnesite tailings in aqueous hydrochloric acid solutions by acid leaching was studied in a batch reactor using hydrochloric acid solutions. Subsequent, production of magnesium chloride hexahydrate (MgCl₂.6H₂O) from leaching solution was also investigated. The effects of temperature, acid concentration, solid-to-liquid ratio, particle size and stirring speed on the leaching process were investigated. The pseudo-second-order reaction model seemed to be appropriate for the magnesium leaching. The activation energy of the leaching process was estimated to be 62.4 kJ mol^− 1. Finally, MgCl₂.6H₂O in a purity of 91% was produced by evaporation of leaching solution obtained at a temperature of 40 °C, 1.0 M acid, solid-to-liquid ratio of 10 g/L, particle size of 100 µm, stirring speed of 1250 rpm and leaching time of 60 min.  相似文献   

水盐体系中有干扰Li⁺离子存在下测定Mg²⁺浓度的掩蔽法研究   总被引：1，自引：0，他引：1       下载免费PDF全文

李红霞  姚燕  曾德文 《盐湖研究》2012,20(2):24-30

在水盐体系中,大量Li+的存在,对EDTA络合滴定法测镁有严重的干扰,使滴定结果偏高。采用体积比为1∶9的正丁醇与无水乙醇作掩蔽剂,探究其在不同Li+/Mg2+摩尔比、不同浓度、不同取样量下的适宜加入量,得出混合醇的加入量与Li+/Mg2+摩尔比有较大关系,与溶液浓度、取样量的多少均无明显关系;同时指出在同一Li+/Mg2+摩尔比下混合醇的加入量有个适宜的范围。该方法的相对误差不大于0.3%。对提高含Li+和Mg2+的水盐体系相化学实验研究的可靠性和精度具有重要意义。  相似文献   

死海溴镁资源开发利用现状          下载免费PDF全文

郭如新 《盐湖研究》2005,13(4):61-66

对以色列和约旦死海中溴镁资源的开发综合利用进行了解述。包括死海卤水组成,资源储量,溴及其衍生物的镁化学制品生产现状。  相似文献   

阻燃用氢氧化镁的表面改性研究现状   总被引：1，自引：0，他引：1       下载免费PDF全文

闫修川  李召好  李法强  马培华  祝增虎 《盐湖研究》2005,13(4):67-71

氢氧化镁作阻燃剂使用时,其无毒、高效、消烟、环保的阻燃特性非常突出,较其它常规无机阻燃剂有十分明显的优势。但由于氢氧化镁与高分子材料基体的相容性较差,从而限制了它的应用。表面处理技术是解决目前这一问题的主要方法,对近年来氢氧化镁阻燃剂表面改性的主要方法和研究现状进行了总结,并分析指出了今后的发展方向。  相似文献   

硼酸镁(铝)晶须增强镁基复合材料中界面特性对比研究   总被引：3，自引：1，他引：3       下载免费PDF全文

金培鹏  许广济  丁雨田  史训兵  刘孝根 《盐湖研究》2007,15(4):32-36,72

对硼酸镁(铝)晶须增强镁基复合材料的界面行为进行了对比研究。对复合材料进行了示差扫描量热分析以及对复合材料中萃取的晶须进行了X射线衍射分析,表明在硼酸镁晶须增强AZ91D镁基复合材料界面无界面反应产物的生成。通过对硼酸镁晶须增强AZ91D镁基复合材料界面的键合状况进行分析和讨论,认为界面的键合是由无反应产物的化学键合、扩散键合及物理键合所组成。另外,根据已有的关于硼酸铝晶须增强镁基和铝基复合材料界面行为的研究结果,分析得出硼酸铝晶须增强镁基复合材料在硼酸铝晶须/AZ91D镁合金界面上的反应产物只有MgO。  相似文献   

碱式氯化镁和氧化镁晶须的制备与表征   总被引：1，自引：0，他引：1       下载免费PDF全文

王在华  冯刚  孙庆国  全宏毅 《盐湖研究》2007,15(4):40-44

以活性氧化镁和氯化镁为原料在水热条件下合成了碱式氯化镁晶须。碱式氯化镁晶须热解后形貌保持得很好,得到氧化镁晶须。制得的晶须长度在200μm左右,直径约0.5μm。采用X射线衍射仪、扫描电镜、热重分析仪表征碱式氯化镁和氧化镁晶须,探讨了各个工艺条件对产物的影响。实验结果表明,碱式氯化镁晶须的最佳工艺条件为:反应时间8~12 h,搅拌速率初始在500 r.min-1左右,120 min时调为1 000 r.min-1,氧化镁与氯化镁的物质的量之比0.10~0.15,氯化镁溶液的浓度4.0 mol.L-1以上,反应温度150~200℃,反应釜的填充度50%~80%。在此条件下制得了形貌良好的碱式氯化镁晶须。  相似文献   

Heat-capacity measurements and absolute entropy of ɛ-Mg2PO4OH     

Catherine Leyx  J. Cornelis Van Miltenburg  Christian Chopin  Lado Cemič 《Physics and Chemistry of Minerals》2005,32(1):13-18

The low-temperature heat capacity of -Mg₂PO₄OH was measured between 10 and 400 K by adiabatic calorimetry. No phase transition was observed over this temperature range. A relative enthalpy increment of 22,119 J mol^–1 and an absolute entropy value of 127.13±0.25 J mol^–1 K^–1 at 298.15 K are derived from the results. The low-temperature heat-capacity data are compared with the DSC data obtained from 143 K to 775 K and show marginal differences in the common temperature range. The latter data are fitted by the polynomial which allows extrapolation to high temperatures.Software information: WINDOWS operating system, WORD word processing, SigmaPlot diagrams exported in tiff format.  相似文献