基于纳米硅/聚合物核壳结构的高循环稳定性固相储锂负极反应

项目名称： 基于纳米硅/聚合物核壳结构的高循环稳定性固相储锂负极反应

项目编号： No.21473128

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 分析化学

项目作者： 王雅东

作者单位： 武汉理工大学

项目金额： 90万元

中文摘要： 硅是一种极具应用前景的高比容量锂离子电池负极材料。然而，由于合金化储锂过程中伴随巨大的体积膨胀，硅负极的循环稳定性较差，制约了其商业化应用。体积膨胀给硅负极带来两方面的负面影响：一是材料颗粒的粉化；二是Si颗粒表面SEI膜的不断破坏和重建。SEI膜的重复生长不仅导致电极充放电库仑效率的降低，以及电解液和锂离子的快速耗竭，而且带来SEI膜的不断增厚，进而造成Si颗粒之间的电接触不良。但目前的研究大多集中在缓冲硅的体积变化方面， 对于SEI膜的持续生长问题目前仍缺乏有效的解决方案。在此，我们提出了一种发展高循环稳定性Si负极的新思路，即将纳米硅颗粒分散嵌埋到锂离子传导型导电聚合物基质中，形成具有核壳结构的Si/聚合物复合物。在此结构中，聚合物基质不仅可以作为缓冲层用来缓解硅的体积变化，而且可以作为保护层用来阻挡硅表面与电解液的直接接触。本工作将围绕聚合物基质的选择、复合物的制备与表征展开研究。

中文关键词： 锂离子电池；硅；负极材料；核壳结构；循环稳定性

英文摘要： Silicon has been considered as a promising alternative anode material for next-generation lithium ion batteries, but the commercial application of Si anodes is still hindered by the poor cyclability. The low cyclability of silicon mainly resulted from the huge volumetric changes during lithium insertion/extraction cycles. Such an enormous volume change brings about two severe problems for Li-ion battery. One is the degradation of the mechanical integrity of the Si anode, leading to the loss of electrical contact and the gradual deactivation of the active materials. The other is the continuous change in the structure and morphology of the solid electrolyte interphase (SEI) on the Si surface. The repeated construction and destruction of the SEI will seriously decrease the coulombic efficiency, and the continuous growth of electronically insulating SEI film can cause electric disconnection between the electrode collector and anode materials. Much research work has been devoted to the relaxation of the volume change of silicon. However, little work has been focused on both the volume change and SEI reconstruction. The improvement of the cyclability of silicon is still not acceptable. In this work, we propose a new strategy to enhance the long-term cyclability of Si anode by embedding nano-Si particles into a Li+ - conductive polymer to form a Si/polymer composite with core-shell structure. In this core-shell structure, the polymeric matrix serves not only as a strong buffer to accommodate the volume change, but also as a protection barrier to prevent the direct contact of Si surface with electrolyte, so as to maintain the mechanical integrity of Si anode and suppress the repeated destruction and construction of SEI on the Si surface. This work will focus on the choice of the polymer matrix, prereparation and characterization of the composite anode materials.

英文关键词： Lithium-ion batteries;Silicon;Anode materials;Core/shell;Cycling stability