摘要
采用第一原理方法计算了两种不同镍含量的锂离子电池富锂锰基三元正极材料Li_(1.2)Ni_(0.32)Co_(0.04)Mn_(0.44)O_(2)(空间群为R3m)和Li_(1.167)Ni_(0.167)Co_(0.167)Mn_(0.5)O_(2)(空间群为C2/m)中氧空位簇的形成能.结果表明,含镍量较少的Li_(1.167)Ni_(0.167)Co_(0.167)Mn_(0.5)O_(2)正极材料中氧空位簇的形成能总是高于含镍量较多的Li_(1.2)Ni_(0.32)Co_(0.04)Mn_(0.44)O_(2)材料中的氧空位簇形成能,这说明含镍量较高的正极材料中氧空位簇更容易形成.无论是含镍量较高的富锂锰基材料,还是含镍量较少的同类材料,过渡金属边上的氧空位簇的形成能总是大于锂离子附近空位簇的形成能,说明氧的脱去更趋向于在Li离子附近发生.较低的温度和较高的氧分压会使氧空位簇的形成能增加,从而抑制氧空位簇的形成.此外,还计算了空位簇边上的过渡金属原子被其它过渡金属原子(Ti和Mo)替位后的氧空位簇形成能.结果表明,除了Li_(1.2)Ni_(0.32)Co_(0.04)Mn_(0.44)O_(2)材料中双氧空位V_(2O-Li)附近的Ni元素被Ti替位外,其余情况下过渡金属Ni和Mn分别被Ti或Mo替位后均能够增大VnO-Li空位簇的形成能,故替位点缺陷的掺杂有抑制氧的损失和提高材料的结构稳定性的作用.
Using the first-principles method,the formation energy values of O-vacancy clusters of two Li-rich Mn-based ternary cathode materials of lithium ion battery with different amounts of nickel,i.e.Li_(1.2)Ni_(0.32)Co_(0.04)Mn_(0.44)O_(2)(space group and Li_(1.167)Ni_(0.167)Co_(0.167)Mn_(0.5)O_(2)(space group C2/m),are calculated.Results show that the formation energy of oxygen vacancy cluster of the material with less nickel content Li_(1.167)Ni_(0.167)Co_(0.167)Mn_(0.5)O_(2) can be always higher than that of the material Li_(1.2)Ni_(0.32)Co_(0.04)Mn_(0.44)O_(2)with higher nickel content.This indicates that the oxygen vacancy clusters are more likely to form in cathode material with higher nickel content.The formation energy of the oxygen vacancy cluster near the transition metal is always greater than that near the lithium ion,indicating that the removal of oxygen tends to occur near the Li ion.Lower temperature and higher partial pressure can increase the formation energy of oxygen vacancy cluster,and therefore inhibit the formation of oxygen vacancy cluster.In addition,the formation energy values of oxygen vacancy clusters with the transition metals in the materials replaced by other transition metals(i.e.,Ti and Mo)are also calculated.The results show that,in addition to the case of Ni replaced by Ti near the double oxygen vacancies near the Li-ion in Li_(1.2)Ni_(0.32)Co_(0.04)Mn_(0.44)O_(2),all the remaining cases of the transition metals Ni or Mn replaced by Ti or Mo always increase the formation energy of the O-vacancy cluster.Therefore,the doping should be able to inhibit the loss of oxygen and improve the structural stability of material.
作者
史晓红
侯滨朋
李祗烁
陈京金
师小文
朱梓忠
Shi Xiao-Hong;Hou Bin-Peng;Li Zhi-Shuo;Chen Jing-Jin;Shi Xiao-Wen;Zhu Zi-Zhong(College of Physical Science and Technology,Xiamen University,Xiamen 361005,China;Hongzhiwei Technology(Shanghai)Co.Ltd.,Shanghai 200120,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第7期390-399,共10页
Acta Physica Sinica
基金
国家重点研发计划(批准号:2016YFA0202601)资助的课题.
关键词
富锂锰基三元材料
氧空位簇
形成能
第一性原理计算
Li-rich Mn-based ternary materials
oxygen vacancy cluster
formation energy
first-principles calculations
