Kuganathan Navaratnarajah, Ganeshalingam Sashikesh, Chroneos Alexander
Department of Materials, Imperial College London, London, SW7 2AZ, United Kingdom.
Depratment of Chemistry, University of Jaffna, Sir Pon Ramanathan Road, Thirunelvely, Jaffna, Sri Lanka.
Sci Rep. 2018 May 25;8(1):8140. doi: 10.1038/s41598-018-26597-w.
Layered LiV(PO)(PO) has attracted considerable interest as a novel cathode material for potential use in rechargeable lithium batteries. The defect chemistry, doping behavior and lithium diffusion paths in LiV(PO)(PO) are investigated using atomistic scale simulations. Here we show that the activation energy for Li migration via the vacancy mechanism is 0.72 eV along the c-axis. Additionally, the most favourable intrinsic defect type is Li Frenkel (0.44 eV/defect) ensuring the formation of Li vacancies that are required for Li diffusion via the vacancy mechanism. The only other intrinsic defect mechanism that is close in energy is the formation of anti-site defect, in which Li and V ions exchange their positions (1.02 eV/defect) and this can play a role at higher temperatures. Considering the solution of tetravalent dopants it is calculated that they require considerable solution energies, however, the solution of GeO will reduce the activation energy of migration to 0.66 eV.
层状LiV(PO₄)₂作为一种新型阴极材料，在可充电锂电池中具有潜在应用价值，已引起了广泛关注。本文采用原子尺度模拟研究了LiV(PO₄)₂中的缺陷化学、掺杂行为和锂扩散路径。研究表明，锂通过空位机制沿c轴迁移的活化能为0.72 eV。此外，最有利的本征缺陷类型是锂弗伦克尔缺陷（0.44 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。在能量上与之接近的唯一其他本征缺陷机制是反位缺陷的形成，即锂和钒离子交换位置（1.02 eV/缺陷），这在较高温度下可能起作用。考虑到四价掺杂剂的固溶，计算表明它们需要相当大的固溶能，然而，GeO₂的固溶将使迁移活化能降低至0.66 eV。
