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采用第一性原理平面波赝势方法计算研究了在LiFePO4的Li位、Fe位和Fe/Li位共掺杂金属原子对材料的电性能和局部结构稳定性的影响关系。结果表明:Li位掺杂(Li0.75Na0.25)FePO4比Fe位掺杂Li(Fe0.75Mn0.25)PO4表现出更好的电子电导性,而局部结构稳定性刚好相反。但是Fe/Li位共掺杂对电子电导性和局部结构稳定性具有双重优化作用,这可能是由Na-2p电子与Li-s电子相互作用引起的。同时,根据计算差分电荷密度关系可以发现共掺杂后会有大量其他原子电荷向Li原子周围偏移,从而改善材料的电子电导性能。
The first-principle plane-wave pseudopotential method was used to study the influence of co-doping metal atoms at the Li site, Fe site and Fe / Li site on the electrical properties and local structural stability of LiFePO4. The results show that Li (Li0.75Na0.25) FePO4 has better electron conductivity than Li (Fe0.75Mn0.25) PO4 doped with Fe, while the local structure stability is the opposite. However, co-doping of Fe / Li sites has a dual optimization of electronic conductivity and local structural stability, which may be caused by the interaction of Na-2p electrons with Li-s electrons. At the same time, according to the calculation of differential charge density relationship, it can be found that a large amount of other atomic charges will be shifted around Li atoms after co-doping to improve the electronic conductivity of the material.