Functionalized Si/SiNx Nanoparticles as Anodes for High-Performance Lithium-Ion Batteries: Gas-phase synthesis, Structural and Electrochemical Investigation

通常，基于纳米Si的负极材料被认为对于高性能锂离子电池（LIB）是非常有前途的。在初步研究中，多功能Si/SiNx纳米结构显示出克服Si基阳极的关键问题，即其结构和电化学不稳定性的有前途的能力。然而，到目前为止，Si/SiNx阳极尚未实现。这是由于无法获得产生足够量的具有目标特性的材料的工艺。基于已建立的用于合成Si纳米颗粒的热壁反应器技术，预期气相合成能够以所需的质量和数量生成Si/SiNx纳米颗粒。该项目的总体目标是通过可扩展的气相合成研究Si/SiNx纳米颗粒的形成，并研究其作为LIB阳极的电化学性能。这包括两项主要任务：了解合成条件-材料-特性的相关性，了解材料-特性-电化学-性能的相关性。为了完成第一个任务，将进行系统的实验，以研究如何合成参数，如NH3/SiH 4的比例，温度和停留时间确定相组成和Si/SiNx纳米颗粒的粒度。第二个任务是合成和研究一系列具有明确特性的Si/SiNx材料。这些材料将用于LIB阳极进行电化学测试，以揭示它们的特性如何影响电池在容量，库仑效率，循环稳定性和充电速率能力方面的性能。将通过各种方法分析Si/SiNx阳极在不同循环阶段的结构和组成演变，包括与阿贡国家实验室合作的原位同步辐射XRD。因此，优化的材料，包括可扩展的合成和加工方法，将在本项目中以迭代的方式开发。

Generally, nano-Si-based anode materials are considered highly promising for high-performance lithium-ion batteries (LIBs). In preliminary studies, multi-functional Si/SiNx nanostructures showed promising capabilities to overcome critical issues of Si-based anodes, namely their structural and electrochemical instabilities. So far, however, Si/SiNx anodes have not been realized. This is due to the unavailability of processes that generate sufficient amounts of materials with targeted properties. Based on the established hot-wall reactor technique for the synthesis of Si nanoparticles it is expected that gas-phase synthesis enables the generation of Si/SiNx nanoparticles in the required quality and quantity. The overall goal of this project is to investigate the formation of Si/SiNx nanoparticles by scalable gas-phase synthesis and to study their electrochemical properties as anodes for LIBs. This includes two main tasks: Understanding the synthesis-conditions - materials-characteristics correlation and understanding the materials-characteristics - electrochemical-performance correlation. To fulfil the first task, systematic experiments will be carried out to study how synthesis parameters such as NH3/SiH4 ratio, temperature, and residence time determine the phase composition and the particle size of the Si/SiNx nanoparticles. The second task requires the synthesis and investigation of a series of Si/SiNx materials with well-defined characteristics. These materials will be implemented in LIB anodes for electrochemical tests to reveal how their characteristics influence the battery performance in terms of capacity, Coulombic efficiency, cycling stability, and charging rate-capability. The structure and the composition evolution on the Si/SiNx anodes at different cycling stages will be analyzed by various methods, including in situ synchrotron XRD in collaboration with the Argonne National Laboratory. As results, optimized materials including scalable synthesis and processing methods will be developed in an iterative way in this project.