共查询到20条相似文献,搜索用时 78 毫秒
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利用球型Ni(OH)2、纳米Co3O4和Al(NO3)3,低温预烧结,固相合成高性能LiNi0.80Co0.15Al0.05O2正极材料.通过XRD,SEM对样品进行结构和形貌研究,采用TG对样品进行热分析,结果显示在空气气氛下,该固相合成的LiNi0.80Co0.15Al0.05O2材料具有良好的层状结构,反映层状结构的006/012和018/110两组峰分裂明显.CV测试结果显示,样品具有良好的氧化还原性.将样品制备成扣式电池进行充放电测试,540℃预烧结12 h,720℃烧结26 h样品表现出最佳电化学性.0.2 C倍率下,首次放电容量达到184.5 mAh/g,首次库伦效率为86.6%,测试结果高于传统固相法;1 C倍率充放电,首次放电容量为159.9 mAh/g,50次循环后容量保持率达到96%,样品具有良好的循环性能. 相似文献
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采用溶胶凝胶法合成了不同温度下的锂离子电池正极材料LiNi0.05Mn1.95O3.95F0.05.使用X射线衍射对合成材料的结构进行了表征.考察烧结温度对其结构及电化学性能的影响.随着烧结温度的升高,尖晶石型结构越来越完整,初始放电比容量增大,但循环性能却逐渐变差.在750℃T烧结温度12h得到了性能较好的LiNi0.05Mn1.95O3.95F0.05,首次放电比容量为109.7mAh/g,50次循环后,其放电比容量仍保持在101.6mAh/g,适合作为锂离子电池的正极材料. 相似文献
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利用液相沉淀法合成得到超细、粒径分布窄的球形V2O5,以该V2O5和LiOH*H2O为原料在较低温度下煅烧得到棒状Li1+xV3O8颗粒.采用XRD、SEM对样品的结构和形貌分别进行了表征.并在电压为1.8~3.8V范围,放电倍率为0.2C对制备的电极材料进行了电池性能测量.结果表明,采用比传统固相法低的温度和时间可以获得单斜晶系的纯相Li1+xV3O8.450℃合成的Li1+xV3O8首次放电比容量达到275mAh/g,550℃合成的Li1+xV3O8在循环15次后的比容量保持率为85%. 相似文献
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富锂氧化物xLi_2MnO_3·(1-x)LiMO_2(M为Co、Ni、Mn等)的比容量可达250~300mAh/g,是高比能量锂离子电池正极材料的首选之一。介绍了材料的晶体结构、嵌/脱锂机制和充放电过程中发生的结构相变,分析讨论了材料出现首次不可逆容量大、电压和容量衰减快、倍率性能和低温性能较差等问题的原因,阐述了材料的合成方法及改性技术,如表面包覆、离子掺杂、形貌和晶面调控以及合成层状相-尖晶石相共生结构的异质材料等。最后从基础研究和应用研究两个方面展望了富锂氧化物材料的发展前景。 相似文献
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James Manuel Chorong Shin Jou-Hyeon Ahn Jung-Pil Noh Ho-Suk Ryu 《Materials Research Bulletin》2010,45(3):265-268
Doped polyaniline with LiPF6 is electrosprayed onto aluminum foil using electrospinning technique, and evaluated as cathode active material for application in room-temperature lithium batteries. Doping level is characterized using FTIR and UV-vis spectroscopy. In FTIR Spectra, characteristic peaks of PANI are shifted to lower bands as a result of doping which indicates the effectiveness of doping. Doping level is also confirmed by UV-vis spectra. Surface morphology of the cathode is studied using scanning electron microscope. Electrochemical evaluation of the cell using electrosprayed PANI as cathode show good cycling properties. The cell delivers a high discharge value of 142.5 mAh/g which is about 100% of theoretical capacity, and the capacity is lowered during cycle and reached 61% of theoretical capacity after 50 cycles. The cell delivers a stable but lower discharge capacity at higher C-rates. 相似文献
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《Materials Research Bulletin》2013,48(4):1737-1740
Iron orthovanadate microrods with layered structure have been synthesized by a simple hydrothermal method. The composition and structure of the microrods were investigated by X-ray powder diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. Electrochemical measurements indicated that the microrods maintained high capacity when used as lithium ion battery cathode. As-obtained iron orthovanadate microrods electrode exhibits a stable and reversible capacity of over 250 mAh g−1 at 16 mA g−1 between 1.6 V and 4.7 V after 15 cycles. Detailed investigations reveal that the layered structure may reduce the lithium ion diffusion path and be helpful for stable capacity. 相似文献
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固相反应法合成了新型锂离子电池正极材料LiFePO4,组装成电池后,室温下(23℃)初始比容量为110mAh/g.以蔗糖分解在LiFePO4电池材料的颗粒间覆碳的方法制备了改性的LiFePO4,对LiFePO4进行表面覆碳改性后其电化学性能包括比容量和充放电效率两方面都得到提高.覆碳后正极材料的初始比容量在室温下达到了140mAh/g,比覆碳前增加了30mAh/g,在循环20周后比容量仍维持在125mAh/g左右;覆碳后正极材料的平均充放电效率在23℃和50℃下分别为91%和93%. 相似文献
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Herein, a comprehensive investigation of the effect of calcination temperature on the physicochemical properties of full-concentration-gradient Li[Ni0.78Co0.10Mn0.12]O2 (FCG NCM78) and the electrochemical performance of FCG NCM78 cathodes was conducted. The electrochemical performance of the FCG NCM78 cathode was significantly influenced by the physical properties of FCG NCM78, such as crystallinity, compositional gradient, and morphology. The crystallinity of FCG NCM78 increased with increasing calcination temperature; however, the compositional gradient and radial alignment of rod-shaped primary particles increasingly disappeared at calcination temperatures exceeding the optimal calcination temperature. FCG NCM78 calcined at the optimal calcination temperature retained the morphological texture of its precursor and demonstrated high crystallinity; the resulting cathode exhibited remarkable cycling stability, thereby retaining 86.3% of its initial capacity after 4000 cycles, and superior rate capability due to the availability of nearly straight diffusion paths for Li-ion transport across adjacent primary particles. In contrast, excessively coarsened FCG NCM78 cathode particles, which are obtained at high calcination temperatures, develop permanent microcracks during cycling, thereby facilitating severe structural damage of the cathode material by parasitic surface reactions and the rapid deterioration of the solid electrolyte interphase layer on the graphite anode surface due to the crossover of dissolved transition-metal ions. Therefore, for superior electrochemical performance, the physicochemical properties of FCG cathode materials should be carefully optimized by controlling the calcination process. 相似文献
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采用溶胶-凝胶法制备层状LiMnO2的正极材料,并对其进行不同比例的过渡元素钴镍镧铈掺杂改性。用XRD以及SEM对其进行物相和表面形貌的分析,同时用锂离子电池模具装配电池以及进行恒电流充放电、循环伏安等电化学测试,分析了掺杂元素对其电化学性能的影响。XRD分析结果表明所合成的锰酸锂材料呈斜方晶系,SEM形貌显示产物为明显的层状结构,循环充放电测试结果表明掺杂2%Ni2%Co6%Ce的层状锰酸锂正极材料的初次放电比容量为161.8mAh/g,循环稳定性较好:而掺杂了6%Co4%La的层状锰酸锂正极材料的初次放电容量为111.5mAh/g,表现了很好的电化学性能。 相似文献
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用一步固相法合成了斜方锰酸锂,对其进行了表征并确定了前驱体化合物烧结中的转变过程,以及相互化合间的烧结机制.结果表明,随着煅烧温度的升高,杂相减少,生长出主体相斜方锰酸锂.在700℃以上可以生成均一相的层状斜方类球状和棒状锰酸锂颗粒.两种颗粒的粒度分别为1~5μm和5~15μm.在充放电循环中,斜方锰酸锂结构易于向尖晶石结构转变.在2.5~4.5V范围内以20mA/g电流进行充放电循环,斜方锰酸锂的初始充电容量达到247mAh/g,放电容量为133mAh/g,50次循环后,容量保持率为92%. 相似文献
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通过溶胶-凝胶烧结法制备了LiFePO4/graphene锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、循环伏安(CV)以及各种电化学检测技术对合成材料的结构、形貌进行了表征。LiFePO4/graphene复合材料的表面上和其中的LiFePO4微小颗粒之间都有石墨烯,说明石墨烯与LiFePO4已很好地融合在一起,形成了具有三维空间结构的立体导电网络,大大地提高了复合材料的电子导电性能及减少了电荷转移电阻,从而充分发挥了活性材料的全部潜力。电化学测量表明LiFePO4/graphene的电化学性能比LiFePO4/C更好。LiFePO4/graphene具有较高的比容量和优良的大倍率性能,在0.1和5C电流充放时,LiFePO4/graphene的比容量分别为163.81和101.57 mAh/g,而LiFePO4/C仅为146.05和54.67mAh/g。LiFePO4/graphene也具有优良循环性能,0.5C循环100次,容量保持率为98.48%。 相似文献