摘要
用共沉淀法和高温固相法合成了单晶LiNi0.6Co0.2Mn0.2-2xTixZrxO2(x=0.0,0.001,0.002,0.003),研究了Ti和Zr部分取代Mn对材料结构、电化学性能和Li+扩散系数的影响。研究结果表明,钛和锆共掺杂能进一步增加Li层间距、改善阳离子混合,从而提高电池容量和倍率性能。半电池循环伏安特性测试表明,与未掺杂材料相比,Ti和Zr共掺杂的LiNi0.6Co0.2Mn0.2O2正极材料具有更好的电化学性能。以LiNi0.6Co0.2Mn0.2-2xTixZrxO2为正极材料制作的扣式电池放电比容量、电荷转移效率和Li+扩散系数均随掺杂元素比例x增大而增加。在3.0~4.3 V电压范围内,LiNi0.6Co0.2Mn0.2-2xTixZrxO2正极材料在x=0.002时,半电池在1C倍率下的放电比容量达到163.2 mAh/g,半电池经过1C倍率循环50次后,放电容量保持率提高到93.2%,高于未掺杂样品(92.1%)。对循环后电池进行交流阻抗测试,结果表明,对过渡金属的部分替代有助于结构内部锂离子扩散和降低电荷转移电阻。
A single-crystal LiNi0.6Co0.2Mn0.2-2xTixZrxO2(x=0.0, 0.001, 0.002, 0.003) is synthesized by using co-precipitation and high-temperature solid-state methods. The impacts of partial substitution of Mn with Ti and Zr on the structure, the electrochemical properties and Li-ion diffusion coefficient of material are discussed. X-ray diffraction(XRD) and scanning electron microscopy(SEM) test results indicate that Ti-Zr co-doping can further improve Li+ layer spacing and cathode ions mixing, thus resulting in an improvement in the capacity and rate performance of batteries. The electrochemical performance is investigated by charge/discharge measurements, cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). It is found that LiNi0.6Co0.2Mn0.2-2xTixZrxO2 displays better electrochemical performance compared with the un-doped cathode. The charge/discharge capacity, charge transfer efficiency and Lithium ion′s diffusion coefficient of button cells made with LiNi0.6Co0.2Mn0.2-2xTixZrxO2 as cathode material are increased with an increase in the percentage amount(x) of the doping element. In the voltage range of 3.0~4.3 V, when x=0.002 for the LiNi0.6Co0.2Mn0.2-2xTixZrxO2 cathode, the discharge specific capacity of half cell at 1 C rate reaches 163.2 mAh/g, and the corresponding retention ratio remains 93.2% after 50 cycles in 1 C rate, which is greater than un-doped samples(92.1%). EIS results reveal that the partial substitution of transition metals contributes to the lithium ion diffusion and reduction of charge transfer resistance within the structure.
作者
贺雨阳
周友元
HE Yu⁃yang;ZHOU You⁃yuan(Changsha Research Institute of Mining and Metallurgy Co Ltd,Changsha 410012,Hunan,China)
出处
《矿冶工程》
CAS
CSCD
北大核心
2019年第6期146-150,155,共6页
Mining and Metallurgical Engineering
关键词
锂离子电池
正极材料
三元正极材料
共掺杂
改性
钛
锆
Li-ion battery
cathode material
tertiary cathode material
co-doping
modification
titanium
zirconium
