基于湍流状碳层织构的硅/碳微球负极材料设计及其储锂性能研究

The research and development of new high performance silicon-carbon composite anode materials is the key to the breakthrough in the field of power batteries. How to efficiently regulate the synergistic effect of carbon structure and cavity space, is an urgent scientific problem for high-performance silicon-carbon composite anode materials. In this project, the precursor is synthesized from the mixture of dispersed nano-silicon and heavy aromatic hydrocarbon by thermal condensation, then it is made into a high performance silicon/carbon microspheres composite anode materials by thermal treatment. It is proposed to design a unique structure with nano-cage encapsulated silicon unit embedded in the turbostratic carbon layer texture of carbon microspheres, giving consideration to silicon volume expansion space, ion electron diffusion channel and mechanical strength, to achieve the organic unity of specific energy, conductivity and mechanical stability of anode materials. Three key scientific problems are solved by means of high-resolution electron microscopy, in-situ spectroscopy and molecular simulation. A controlled synthesis mechanism of oil soluble, organic coated and dispersed nano-silicon is established, the regulation mechanism of nucleating agent (nano-silicon) on the microstructure of mesocarbon microbeads is revealed, then the structure-activity relationship of micro-nano structure (carbon structure and cavity) and lithium storage performance is established. This research provides a theoretical basis for the design and synthesis of high performance silicon-carbon composite anode materials, and promotes the application of high energy and high power density lithium ion power batteries, which has important scientific significance and practical value.

新型高性能硅碳复合负极材料的研发，成为动力电池领域重大突破的关键。如何高效调控碳结构和空腔空间的协同作用，是高性能硅碳复合负极材料亟待解决的科学问题。本项目提出由分散型纳米硅和重质芳烃共混热缩聚合成前驱体，再经热处理制备硅/碳微球复合负极材料。拟设计纳米笼封装硅单元内嵌于碳微球湍流状碳层织构的独特结构，兼顾硅体积膨胀空间、离子电子扩散通道和机械强度，实现负极材料比能量、导电性和机械稳定性的有机统一。结合高分辨率电镜技术、原位光谱手段和分子模拟计算，突破三个关键科学问题：建立油溶性-有机包覆-分散型纳米硅的可控合成机制；揭示成核剂（纳米硅）对中间相碳微球微观结构的调控机制；进而建立负极材料微纳结构（碳结构和空腔）与储锂性能的构效关系。该研究将为高性能硅碳复合负极材料的设计合成提供理论依据，同时对推动高能量密度和高功率密度锂离子动力电池的应用，具有重要的科学意义和实用价值。

新型高性能硅碳复合负极材料的研发，成为动力电池领域重大突破的关键。如何高效调控碳结构和空腔空间的协同作用，是高性能硅碳复合负极材料亟待解决的科学问题。本项目基于纳米笼封装硅单元内嵌于湍流状碳层织构的独特结构，设计合成硅碳复合负极材料，兼顾了硅体积膨胀空间、离子电子扩散通道和机械强度。研究了分散型有机包覆纳米硅的合成和调控，形成了有机聚合物包覆硅纳米颗粒表面的可控合成方法，建立了有机包覆层厚度的调控策略和机制。考察了有机包覆层在后续热处理中作为模板热解形成空腔的规律，初步实现了硅碳复合负极材料空腔空间的调控，探究了成核剂对湍流状碳层织构和空腔等碳质微观结构演变的影响规律。进而分析了碳结构与空腔空间的协同作用，探讨了硅碳微纳结构和储锂性能的关联，建立了硅碳负极材料湍流状碳层织构和空腔与储锂性能的构效关系。该研究将为高性能硅碳复合负极材料的设计合成提供理论依据，同时有望推动高能量高功率密度锂离子动力电池的应用，具有重要的科学意义和实用价值。