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，我们将研究无定形和结晶硅纳米粒子均匀分散在SiCN（O）和SiCO基陶瓷衍生的聚硅氮烷和聚硅氧烷。将结合商业电解质和作为参比/对电极材料的金属锂来研究所得SiCN（O）/Si和SiCO/Si材料的电化学性能。为了进一步研究这种新型负极材料在完整电池中的应用，我们将使用商用正极材料（LiCoO_2，LiFePO_4），通过基于密度泛函理论的总能量计算，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、量热测量和热力学建模相结合，探索了组分中间化合物的存在。我们将通过使用计算方法（Calphad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形成过程。最后，复合材料的机械稳定性将通过嵌入和脱嵌结构的分子动力学模拟来研究。

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.