Nanoscale layered K2Ti4O9 was prepared by solid-state method using nanosca le TiO2 with average particle size of 20 nm as the raw material. The obtained na noscale K2Ti4O9 was further used as the host material for the...Nanoscale layered K2Ti4O9 was prepared by solid-state method using nanosca le TiO2 with average particle size of 20 nm as the raw material. The obtained na noscale K2Ti4O9 was further used as the host material for the preparation of Al2 O3 pillared K2Ti4O9 and the K2Ti4O9 was undergone H+-exchange, alkylamine-pre-ex pansion, Keggin-pillaring and heat-treatment. The products were characterized by XRD, TEM and BET methods. The interlayer distance of K2Ti4O9 was expanded step by step during the pillaring procedure and the Al2O3 pillared H2Ti4O9 with narro w pore-size distribution and high surface area (212.8 m2·g-1) was obtained.展开更多
采用共沉淀法制备碳酸盐前驱体,通过高温固相反应制备Na+掺杂的富锂锰基正极材料Li1.2-xNaxNi0.13Co0.13Mn0.54O2(x=0,0.01,0.02,0.04,0.08).X射线衍射(XRD)和扫描电镜(SEM)分析表明,x≤0.04时为层状富锂锰基材料的α-NaFeO 2六方相结构...采用共沉淀法制备碳酸盐前驱体,通过高温固相反应制备Na+掺杂的富锂锰基正极材料Li1.2-xNaxNi0.13Co0.13Mn0.54O2(x=0,0.01,0.02,0.04,0.08).X射线衍射(XRD)和扫描电镜(SEM)分析表明,x≤0.04时为层状富锂锰基材料的α-NaFeO 2六方相结构,Na掺杂量过大时颗粒表面出现团聚絮状物并发现第二相—P2型层状氧化物.电化学测试发现适量的Na掺杂可提高材料的比容量、倍率和循环性能;掺杂量为0.02时电化学性能最佳:在2.0~4.6 V充放电,Li 1.18 Na 0.02 Ni 0.13 Co 0.13 Mn 0.54 O 2在0.1 C放电比容量为273.4 mAh/g,首次库伦效率为93.1%,1C循环100次后容量超过200 mAh/g,保持率为84.3%.离子半径较大的Na+占据Li位,起到柱撑作用,稳定了结构,增大了层间距,利于Li^+扩散;此外,材料表面形成的P2型层状氧化物能够减缓层状结构向尖晶石结构的转变,从而提高了电化学性能.展开更多
文摘Nanoscale layered K2Ti4O9 was prepared by solid-state method using nanosca le TiO2 with average particle size of 20 nm as the raw material. The obtained na noscale K2Ti4O9 was further used as the host material for the preparation of Al2 O3 pillared K2Ti4O9 and the K2Ti4O9 was undergone H+-exchange, alkylamine-pre-ex pansion, Keggin-pillaring and heat-treatment. The products were characterized by XRD, TEM and BET methods. The interlayer distance of K2Ti4O9 was expanded step by step during the pillaring procedure and the Al2O3 pillared H2Ti4O9 with narro w pore-size distribution and high surface area (212.8 m2·g-1) was obtained.
文摘采用共沉淀法制备碳酸盐前驱体,通过高温固相反应制备Na+掺杂的富锂锰基正极材料Li1.2-xNaxNi0.13Co0.13Mn0.54O2(x=0,0.01,0.02,0.04,0.08).X射线衍射(XRD)和扫描电镜(SEM)分析表明,x≤0.04时为层状富锂锰基材料的α-NaFeO 2六方相结构,Na掺杂量过大时颗粒表面出现团聚絮状物并发现第二相—P2型层状氧化物.电化学测试发现适量的Na掺杂可提高材料的比容量、倍率和循环性能;掺杂量为0.02时电化学性能最佳:在2.0~4.6 V充放电,Li 1.18 Na 0.02 Ni 0.13 Co 0.13 Mn 0.54 O 2在0.1 C放电比容量为273.4 mAh/g,首次库伦效率为93.1%,1C循环100次后容量超过200 mAh/g,保持率为84.3%.离子半径较大的Na+占据Li位,起到柱撑作用,稳定了结构,增大了层间距,利于Li^+扩散;此外,材料表面形成的P2型层状氧化物能够减缓层状结构向尖晶石结构的转变,从而提高了电化学性能.
