Understanding the influence of crystal structures on properties is significant in the future optimization and design of Li-ion battery cathodes. By using the first-principles calculations, we perform a comprehensive investigation on the crystal structure, phase stability and electrochemistry of three new predicted Li₂FeSiO₄ polymorphs with 1D (One-Dimensional), 2D and 3D Fe-Si-O frameworks, i.e. Cmcm, Pmna and P2₁2₁2₁, respectively. Three Li₂FeSiO₄ polymorphs studied here are all mechanically, dynamically and thermodynamically stable. The Pmna is the favored phase at lower temperature and higher pressure, while P2₁2₁2₁ and Cmcm phases could be obtain by quenching of fast cooling from higher temperature. Three Li₂FeSiO₄ polymorphs with different Fe-Si-O frameworks possess similar redox reactions mechanism. However, the oxidation potentials of Fe²⁺/Fe³⁺ reaction depends on the Fe-Si-O frameworks, which can be attributed to different FeO interactions. In addition, the phase transformation due to Li/Fe antisite could occur in Cmcm and Pmna polymorphs upon delithiated from Li₂FeSiO₄ to LiFeSiO₄. While, P2₁2₁2₁ polymorph with 3D Fe-Si-O framework shows better structural stability upon cycling. Finally, the Li diffusion mechanism in these three predicted polymorphs is also studied.

了解晶体结构对性能的影响对于锂离子电池正极的未来优化和设计具有重要意义。通过使用第一原理计算，我们执行对三个新的预测锂的晶体结构，相稳定性和电化学全面调查₂ FeSiO _4层的多晶型与1D（一维），2D和3D的Fe-Si-O的框架，即Cmcm，Pmna和P 2 ₁ 2 ₁ 2 ₁。本文研究的三种Li ₂ FeSiO ₄多晶型物在机械，动力学和热力学上均稳定。该PMNA在较低的温度和较高的压力下是优选的相，而P 2 ₁ 2 ₁ 2 ₁和Cmcm相可以通过淬灭从较高温度的快速冷却获得。具有不同Fe-Si-O骨架的三种Li ₂ FeSiO ₄多晶型物具有相似的氧化还原反应机理。然而，Fe ²⁺ / Fe ³⁺反应的氧化电位取决于Fe-Si-O骨架，这可归因于不同的Fe O相互作用。此外，Li / Fe反位导致的相变可能发生在从Li脱锂的Cmcm和Pmna多晶型物中。₂ FeSiO ₄至LiFeSiO ₄。而具有3D Fe-Si-O骨架的P 2 ₁ 2 ₁ 2 _{1 1 1}多晶型物在循环时表现出更好的结构稳定性。最后，还研究了这三种预测的多晶型物中Li的扩散机理。