摘要
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.
Derived from carbonate precursor,the Na-doped lithium-rich manganese-based cathode material Li 1.2-xNaxNi0.13Co0.13 Mn0.54 O2(x=0,0.01,0.02,0.04,0.08)were prepared by using high temperature solidstate reaction.The SEM and XRD results indicate that the Li1.2-xNaxNi0.13Co0.13Mn0.54O2 show standard lamellarα-NaFeO 2 phase structure when x≤0.04,but the agglomerated flocs appeared on the particle surface and the P2 type layered oxides is found when x>0.04.Electrochemical tests show that the proper amount of Na doping can improve the specific capacity,rate and cycle performance.In the voltage range of 2.0~4.6 V,the initial discharge capacities and Coulombic efficiency of Li 1.18 Na 0.02 Ni 0.13 Co 0.13 Mn 0.54 O 2 are 273.4 mAh/g and 93.1%at 0.1 C,respectively.Moreover,the capacity is over 200 mAh/g at 1 C and the retention rate is 84.3%after 100 cycles.Na+with larger ionic radius occupies the Li slab,which acts as a pillar to make the structure stable,and the increased interlayer spacing enhance the diffusion of Li+;Moreover,the P2 type layered oxides existing on the surface might suppress the phase transformation from layered structure to spinel,all of these improve the electrochemical performance.
作者
王策
王俊
陈彦彬
刘亚飞
Wang Ce;Wang Jun;Chen Yanbin;Liu Yafei(Beijing General Research Institute of Mining and Metallurgy,Beijing 100044,China;Beijing Easpring Material Technology Co,Ltd,Beijing 100044,China)
出处
《材料与冶金学报》
CAS
北大核心
2019年第4期300-304,共5页
Journal of Materials and Metallurgy
基金
北京矿冶科技集团青年创新基金(04-1901)
