Kuganathan Navaratnarajah, Chroneos Alexander
Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom.
Faculty of Engineering, Environment and Computing, Coventry University, Priory Street, Coventry, CV1 5FB, United Kingdom.
Sci Rep. 2019 Jan 23;9(1):333. doi: 10.1038/s41598-018-36398-w.
Polyanion phosphate based LiV(PO) material has attracted considerable attention as a novel cathode material for potential use in rechargeable lithium ion batteries. The defect chemistry and dopant properties of this material are studied using well-established atomistic scale simulation techniques. The most favourable intrinsic defect process is the Li Frenkel (0.45 eV/defect) ensuring the formation of Li vacancies required for Li diffusion via the vacancy mechanism. Long range lithium paths via the vacancy mechanism were constructed and it is confirmed that the lowest activation energy of migration (0.60 eV) path is three dimensional with curved trajectory. The second most stable defect energy process is calculated to be the anti-site defect, in which Li and V ions exchange their positions (0.91 eV/defect). Tetravalent dopants were considered on both V and P sites in order to form Li vacancies needed for Li diffusion and the Li interstitials to increase the capacity respectively. Doping by Zr on the V site and Si on the P site are calculated to be energetically favourable.
基于聚阴离子磷酸盐的LiV(PO)材料作为一种潜在用于可充电锂离子电池的新型正极材料，已引起了相当大的关注。使用成熟的原子尺度模拟技术研究了该材料的缺陷化学和掺杂剂性质。最有利的本征缺陷过程是锂弗伦克尔缺陷（0.45 eV/缺陷），它确保了通过空位机制进行锂扩散所需的锂空位的形成。构建了通过空位机制的长程锂路径，并证实迁移的最低活化能（0.60 eV）路径是具有弯曲轨迹的三维路径。计算得出第二稳定的缺陷能量过程是反位缺陷，即锂和钒离子交换位置（0.91 eV/缺陷）。为了分别形成锂扩散所需的锂空位和增加容量的锂间隙原子，在钒和磷位点上都考虑了四价掺杂剂。计算得出在钒位点上掺杂锆和在磷位点上掺杂硅在能量上是有利的。
