Nanocomposites as anode materials for lithium ion batteries: Synthesis, thermodynamic characterization and modeling of nanoparticular silicon dispersed in SiCN(O) and SiCO-based matrices

在这个项目中，我们将研究非晶态和晶体硅纳米颗粒均匀分散在由聚硅氧烷和聚硅氧烷衍生的SiCN(O)和sico基陶瓷中。SiCN(O)/Si和SiCO/Si材料的电化学性能将与商业电解质和金属锂作为参考/对电极材料结合研究。为了在完整电池中进一步研究新的负极材料，将使用商用正极材料（LiCoO2, LiFePO4）。通过基于密度泛函理论的总能量计算，我们将研究锂离子在硅纳米颗粒和陶瓷基体中的动力学，并与实验结果进行比较。通过量子力学计算、量热测量和热力学模型的结合，探索了这些成分的中间化合物的存在。我们将使用计算方法（calphhad方法）来研究上述材料的热力学，以澄清相反应。此外，我们将进行高温溶液量热法来测量感兴趣的材料的生成焓。最后，将通过嵌层和脱嵌层结构的分子动力学模拟来研究复合材料的力学稳定性。

In this project we will investigate amorphous and crystalline silicon nanoparticles homogeneously dispersed in a SiCN(O)- and SiCO-based ceramic derived from polysilazane and polysiloxane. The electrochemical performance of the resulting SiCN(O)/Si and SiCO/Si material will be studied in combination with commercial electrolytes and metallic lithium as reference/counter electrode material. For further studies of the new anode material in a complete battery, commercial cthode material (LiCoO2, LiFePO4) will be used.By means of total energy calculations based on density functional theory we will study the kinetics of the lithium ions in the Si nanoparticles and ceramic matrices and compare them with experimental findings. The existence of intermediate compounds of the constituents is explored by a combination of quantum mechanical calculations, calorimetric measurements and thermodynamic modeling. We will investigate the thermodynamics of the aforementioned materials by using computational methods (Calphad approach) for clarifying phase reactions. Additionally, we will perform high temperature solution calorimetry to measure enthalpies of formation for the materials of interest. Finally, the mechanical stability of the composite will be investigated by molecular dynamics simulations of intercalated and deintercalated structures.