Al2O3包覆LiNi0.8Co0.2O2正极材料及其电化学性能

为了减少锂离子电池正极材料与电解液的相互作用,用沉淀法在LiNi0.8Co0.2O2表面包覆一层Al2O3,并通过电化学测试、扫描电镜和X射线衍射研究其表面形貌和晶体结构.结果表明,经过表面包覆后,有效地抑制了电解液对正极材料的侵蚀,虽然初始放电容量略有降低,但循环性能明显改善;Al2O3包覆量对LiNi0.8Co0.2O2电化学性能存在影响,包覆量为0.7%(质量分数)的样品性能最优.     

掺钴对尖晶石型LiMn_2O_4正极材料性能影响

采用固相合成法制备了锂离子电池正极材料用尖晶石型LiMn2O4正极材料,并通过加入Co对材料进行了掺杂改性研究;用X射线衍射(XRD)和扫描电镜(SEM)研究了材料的晶体结构和微观形貌,充放电循环实验对材料的电化学性能进行了测试。结果表明:纯相尖晶石型LiMn2O4初始放电比容量为118.91 mA.h/g,循环25次后放电比容量为107.03mA.h/g,比容量保持率为90.01%;掺杂Co的材料同样具有尖晶石型结构,初始放电比容量略有降低,但循环性能有明显改善,掺Co改性样品Li1.05Co0.04Mn1.96O4的初始放电比容量为114.55mA.h/g,25次充放电循环后,放电比容量为105.76mA.h/g,比容量保持率为92.33%。     

LiNi0.6Co0.1Mn0.3O2正极材料的合成与性能

采用共沉淀-高温固相法制备LiNi0.6Co0.1Mn0.3O2锂离子正极材料,并使用X 射线衍射仪（XRD）和扫描电镜（SEM）技术分别表征其结构和形貌.然后将所得LiNi0.6Co0.1Mn0.3O2正极材料组装成扣式电池,并表征其电化学性能,探讨烧结温度和锂配量对其电化学性能的影响.结果表明：所得LiNi0.6Co0.1Mn0.3O2正极材料的放电比容量随烧结温度的升高而增大,且在900℃时表现出最佳的电化学性能.室温下,1C倍率下,锂配量(n(Li)/n(Ni+ Co+ Mn)=1.09)时,正极材料的首次放电容量为143.7 mAh/g,50次循环后,正极材料的放电比容量仍有141.3 mAh/g,容量保持率为98.3%.     

AlF_3包覆LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2正极材料及其电化学性能

采用喷雾干燥法制备Li Ni1/3Co1/3Mn1/3O2正极材料,溶胶—凝胶法制备Al F3包覆Li Ni1/3Co1/3Mn1/3O2正极材料。通过XRD、SEM、电化学测试等对Al F3包覆Li Ni1/3Co1/3Mn1/3O2正极材料的结构、形貌和电化学性能进行研究。结果表明:Al F3包覆Li Ni1/3Co1/3Mn1/3O2正极材料为α-Na Fe O2型结构,属空间群。样品为类球形,颗粒大小均匀。包覆后的样品首次放电容量略有降低,但是显著提高了其循环性能,其首次充放电容量为148 m A·h/g,25次充放电循环后容量保持率为93.9%。     

异丙醇协助Al_2O_3包覆LiMn_2O_4合成及高温电化学性能研究

采用溶胶凝胶法,以硫酸铝、异丙醇(IPA)为原料对Li Mn2O4进行包覆。合成了含2%(质量分数)Al2O3表面包覆的Li Mn2O4电极材料。利用场发射扫描电镜(FESEM)对制备材料的形貌进行表征。结果显示,异丙醇协助包覆后材料表面呈现均匀分布的Al2O3颗粒。在55℃,3.0~4.5 V,1C充放电测试表明,IPA协助包覆可以显著提高Li Mn2O4正极材料高温下的循环稳定性。以异丙醇协助的Al2O3包覆Li Mn2O4材料作为正极,100次循环容量保持率为87.3%,而未加异丙醇包覆后的Li Mn2O4材料100次循环容量保持率为82.2%,未经过包覆的材料只有74.1%。不同倍率恒流充放电测试结果表明,异丙醇协助包覆能够改善Li Mn2O4的倍率性能,在5C和10C的放电倍率下的放电比容量分别达到了102.1和91.0 m Ah·g-1。通过电感耦合等离子体质谱仪(ICP)测试样品在电解液中Mn的溶解浓度。结果显示,高温(55℃)储存20 d后,异丙醇协助包覆的Li Mn2O4材料中Mn在电解液中的浓度仅为58.7×10-6,远远低于未加异丙醇包覆的和未经过包覆的。     

Al_2O_3预包覆尖晶石LiMn_2O_4的电化学性能

将Li2CO3和电解二氧化锰混合球磨,得到尖晶石(LiMn2O4,简称为LMO)的前驱体,采用化学沉积法在前驱体的预烧产物表面包覆Al(OH)3,然后在750℃/6h条件下煅烧,得到Al2O3/LiMn2O4复合粉末(称为Al2O3预包覆,包覆粉末记为P-LMO);同时采用传统方法,在前驱体的煅烧产物(LiMn2O4粉末)表面包覆Al(OH)3,然后在300℃/3h条件下热处理,得到Al2O3/LiMn2O4复合粉末(称为煅烧包覆,复合粉末记为C-LMO),对这2种包覆法制备的Al2O3/LiMn2O4复合粉末的物相结构、形貌、包覆层的厚度与粒度分布等进行对比分析,并对包覆粉末进行电化学性能测试。结果表明,Al2O3均匀地包覆在LiMn2O4的表面,包覆层厚度约为10nm;Al2O3/LiMn2O4复合粉末的晶格常数随Al2O3包覆量增加而增加;预包覆粉末颗粒呈类球形,平均粒径(0.3μm)明显小于煅烧包覆的平均粒径(0.5μm);预包覆粉末的Al2O3包覆层能有效减少循环过程中电荷转移阻抗的增加,并减少Mn的溶解,其循环性能优于煅烧包覆粉末。在3.2~4.5V的充放电区间内,Al2O3包覆量(摩尔分数)为2%的预包覆LiMn2O4材料显示出优良的电化学性能,55℃下0.1C的首次放电容量为114.0(mA·h)/g,0.5C倍率下50次循环后容量保持率为87.3%。     

钴含量对锂离子电池正极材料LiCo2xNi0.5-xMn0.5-xO2的性能影响

采用共沉淀法合成了锂离子电池正极材料LiCo2xNi0.5-xMn0.5-xO2(2x=0.1,0.2,0.33和0.5).对产物进行了XRD,SEM、充放电和DSC测试,以考察不同Co含量2x对材料的结构、电化学性能和热稳定性能的影响.结果表明,随着材料中Co含量2x的提高,材料的品格参数和晶胞体积逐渐减小,材料的循环性能和倍率放电能力得到改善.特别当2x=0.33时,材料具有较好的电化学性能:首次放电容量为175 mAh·g-1,30次循环后容量保持率为89.1%.同时其具有最好的热稳定性能.     

包覆碳对LiFePO4正极材料性能的影响

采用二步固相法在750℃、24h的条件下合成了纯相的和包覆碳的LiFePO4锂离子正极材料,研究了包覆碳对材料性能的影响,并结合XRD、SEM和充放电测试等手段对合成材料的结构、形貌和电化学性能进行了分析。实验结果表明：LiFePO4／C正极材料具有更小的粒径和更紧密的颗粒分布,其中包覆碳为5％的材料电化学性能最好,首次放电比容量有129．6mAh／g,分别以0．2mA和1．0mA的电流充放电循环10次后其比容量保持在120．7mAh／g和92．0mAh／g,保持率分别达100．9％和95．2％。     

非均匀沉淀法包覆合成LiNi0.9 Co0.07 Mn0.03O2锂离子正极材料

采用非均匀沉淀法包覆合成了LiNi0.9Co0.07Mn0.03O2锂离子正极材料.前驱体合成中各工艺条件与包覆材料的比表面积和电化学性能息息相关.试验研究了沉淀剂、搅拌速度、pH值和氨水浓度对包覆沉淀的影响及煅烧过程对材料电化学性能的影响.结果表明:在优化实验条件下Co/Mn复合包覆在β-Ni(OH)2表面上;正极LiNi0.9Co0.07Mn0.03O2首次放电容量为195mAh·g-1,50次循环后容量仍保持为188.6mAh·g-1.循环伏安研究表明:与LiNiO2相比,Co/Mn复合包覆合成正极材料LiNi0.9Co0.07Mn0.03O2的相变得到很好的抑制,材料显示出良好的循环性能.     

烧结气氛对无钴镍基正极材料LiNi_(0.7)Mn_(0.3)O_2性能的影响

采用共沉淀-高温固相法,控制烧结气氛制备出LiNi0.7Mn0.3O2.借助扫描电子显微镜(SEM)、X射线衍射分析(XRD)、氧气分析仪、电池测试系统及电化学工作站对不同气氛条件下制备的LiNi0.7Mn0.3O2进行结构、形貌、固相反应过程氧气浓度变化、电性能和内阻的表征.研究结果表明,烧结过程存在2次明显吸氧阶段且全程通高纯氧制备的材料有更好的球形度,层状结构更完整,充放电性能及循环稳定性都更好,内阻也较小;在2.75~4.35V电压范围内,以0.2C进行充放电,其首次放电比容量高达191.0mAh/g,70周循环后容量保持率为95.2%.烧结过程中由一种气氛切换为另一种气氛比烧结全程不通气或通空气所制备材料的性能差,但其首次比容量都低于184.0mAh/g,70周循环后的容量保持率也都不足85.0%.     

熔炼次数对M17返回料合金成分、组织和性能的影响

实验结果表明,M17铸造高温合金(%:0.16C、8.79Cr、5.79A1、4.93Ti、3.29Mo、15.20Co、0.78V、0.015B、0.073Zr、0.002S、0.001P、0.001 1O、0.001 0N)经25 kg真空感应炉返回重熔后,Si含量随重熔次数的增加而略有增加,合金中主要元素和其它杂质元素S、P、H的含量变化不大,而氧、氮略有增加;合金中初生碳化物由新合金中的草书体逐渐向返回合金块状转变,初生碳化物的遗传性堵塞合金凝固时的补缩通道,使返回料合金的疏松倾向增大,高温塑性下降较大。     

China's Major Non-ferrous Metals Imports & Exports

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Zinc Production by Province in 2014

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80% of Chinese Firms Purchasing Overseas Mines Ended up in the Red

<正>Minmetals Resources acquired the world’s largest copper mine under construction for USD5.85 billion.One after another,listed companies Jien Nickle,China Molybdenum and Chihong Zinc and Germanium raised money to get involved in overseas mining projects…SOEs and private enterprises are engaged in a frenzy of overseas mine purchasing.A reporter with Economic     

Copper Processing Profit Dropped Sharply,Copper Consumption Will Face Impact in the Second Half of the Year

正Judging from China’s copper consumption field,the biggest consumption unit is electric power,which accounts for 47%of total consumption;it is followed by light industry sector,including household electrical appliance,machinery,durable goods and hardware etc,which accounts for 22%of total consumption;followed by transportation field,     

Central Geological Prospecting Fund Newly Added 16.47 Million Tonnes of Bauxite in 2013

正In 2013,the Central Geological Prospecting Fund(CGPF)Project newly discovered 15 ore fields,including 3 large above ore fields,and 5medium sized ore fields.The reporter learned from the recently published"Annual Report of Central Geological Prospecting Fund Project(2013)"that,from 2006 to 2013 the CGPF     

Manufacturers of Copper Tube for Central Air Conditioner Use Face Mounting Pressure in the Final Quarter of the Year

正This year,the investment growth rate of real estate industry continued to slow down,sold area of commercial housing also dropped significantly,which brought huge pressure to the domestic air conditioning manufactures.In the first half of the year,by relying on high growth in national financial expenditure,along with investment in public infrastructure     

Xinjiang Ranks No.1 in Production of Primary Aluminum in China

正Kang Yi,Honorary Chairman of China Nonferrous Metals Industry Association,said recently at the Forum on Development of the Non-ferrous Metals Industry in Central and Western China held in Zhengzhou that,as more and more electrolytic aluminum factories in Xinjiang came into operation,the electrolytic aluminum output of Xinjiang had reached2,275,000 tons in the first 7 months this year,     

Shenhuo Coal Industry and Electricity Power Completed800,000 t/a Aluminum Project in Xinjiang

正"Xinjiang project has been completed according to schedule,but total completion and total start of production are two different concepts,after completion it still needs a gradual process of reaching production target."On the morning of November 3,Shenhuo Coal Industry and Electricity Power told investors the above statement on the investor interaction platform.     

Guangdong Metal Transaction Center has Become the Second Largest Precious Metal Transaction Platform Nationwide

正The reporter learned from Guangdong Province Precious Metal Transaction Center that in 2013the Center maintained healthy development momentum,and had become the second largest precious metal transaction platform in China in terms of market size;currently Guangdong is quickening steps of financial innovation for the Center,aiming to build a transaction center with international core competitiveness.