导电水凝胶原位修饰石墨烯/SiOX-Si及储锂研究

Currently, exploring high-capacity anode materials has been one of the most important targets for lithium ion batteries, and silicon/carbon composite materials have been considered as the preferred anode materials for a new generation of lithium ion batteries due to their high practical values and excellent electrochemical performances. The elaborate assembly of Si-based nanoscopic active components for lithium-ion anodes into macroscopic materials and complete exertion of their unique properties in practical applications are significantly important for developing high-performance lithium-ion batteries used in many fields ranging from electric vehicles to energy storage for many types of intermittent renewable energy sources. This project will target potential utilization of the graphene, conductive hydrogels and SiOX-Si(CHs/G/ SiOX-Si) composites in lithium-ion batteries, propose to assemble a kind of new silicon-carbon nanohybrids with a way of the graphene doped hierarchical structure at nanoscale, and realize the low-cost large-scale synthesis of these silicon-carbon hybrid anodes for lithium-ion batteries while simultaneously endowing them with uniform, stable, and tunable structures from both the macro and micro perspectives. We will specifically aim at the following aspects: clarifying the performance coupling and functional integration mechanism forCHs/G/SiOX-Sicomposites; conducting the formation and evolution mechanism of the micro-nano structures in the CHs/G/SiOX-Si composites and revealing the interface incorporation and morphology control science. We expect to obtain a reasonable method to solve the serious problems of Si-base anode materials such as large volume expansion, quick energy decay, poor cycling performance, poor conductivity and other problems during charge and discharge, which are the key scientific problems to hinder the development of lithium ion battery. The key materials and devices with independent intellectual property rights will be developed in this project, which to fuel extensive applications of high performance LIBs in the future.

高容量负极材料已经成为锂离子电池发展的目标之一，而硅碳复合材料因其较高的实用价值和良好的电化学性能而成为新一代锂离子电池负极材料的首选。 设计新型硅基复合材料的结构并使其特性在宏观应用中得以充分发挥对发展高性能锂离子电池具有重要意义。本项目探索导电水凝胶/石墨烯/硅基复合材料在锂离子电池领域的应用，研究从掺杂石墨烯的导电水凝胶在硅基上的原位聚合制备技术，实现在宏观和微观上结构统一、稳定和可调控的硅碳纳米负极的低成本制备；揭示这类硅碳材料的组分、形态和结构对其性能的影响，阐明硅组分的尺寸、形态和结构与其性能的关联，阐明导电水凝胶/石墨烯/硅基复合材料的功能集成及性能耦合机制；期望为解决硅负极材料应用发展的关键科学问题做出有益补充。

本项目采用水热法制备纳米棒状SiOx@C材料，系统考察了不同碳源对于硅基材料形貌、结构和电化学性能的影响。又以一氧化硅为硅源，选取F掺杂的C作为修饰材料，设计合成了核壳SiO@F-doped C 复合材料，揭示了核壳结构和材料表面的孔隙对于缓冲锂离子在脱嵌过程中引起的硅基材料体积膨胀具有积极意义。再以静电纺丝法合成SiO2/C 复合纤维材料，实现均匀分散的SiO2颗粒被紧密包裹在碳纤维中，既提高了硅基材料的导电性也在维持电极材料结构稳定方面起了突出作用。在上述工作基础上，采用原位聚合法制备了SiOx-Si/rGO/PPy复合材料，研究和分析了导电水凝胶PPy对材料结构、形貌和性能的影响规律，证实了导电水凝胶聚吡咯（PPy）在维持硅碳材料结构稳定性方面起了重要作用；基于对导电水凝胶种类的延伸探索，以原位聚合法制备了SiOx-G/PAA-PANi复合材料，该电极材料证实了交叉掺杂的三维立体导电水凝胶聚丙烯酸-聚苯胺（PAA-PANi）不仅能缓冲硅在锂离子脱嵌过程中的体积膨胀，还可以为锂离子传导提供更多的通道。另外，分别利用石墨烯和铜离子掺杂修饰制备了SiOx-G/PAA-PANi/graphene复合材料和SiOx-G/PAA-PANi/Cu复合材料，两种电极材料的储锂性能与循环稳定性能均得到了显著提高，证实了选取导电性更强的基质对导电水凝胶改性能更加有效的实现硅基材料高容量和长循环性能，深入研究了石墨烯、铜离子掺杂导电水凝胶修饰硅碳负极材料的嵌锂机制。对导电水凝胶修饰硅碳材料的深入探索有了一定的拓宽，对研究硅基负极材料领域有着重要的突破性意义。