互穿网络结构硅/碳复合材料的构筑及其嵌脱锂机制研究

The preparation of kinetically stabilized nano/micro-structured electrode materials is currently one of core issues on lithium storage materials. It is proposed in the application project to construct new kinetically stabilized materials such as interpenetrating network (IPN)-structured Si/C composite materials,in which cross-linked polymers are synthesized by Suzuki coupling and graft copolymerization methods and used as carbon precursors. The advantages of the cross-linked polymer-based carbon materials such as stable structure, good stress buffering,three-dimensional conductive channel and short ion migration pathway are applied to ease those problems related to low capacity, poor rate capability and short cyle life caused by structural pulverization, SEI breakage and slow ion/electron tranfer rate of Si electrode during lithium insertion/extraction process. The influences of polymer structure, carbonization process, composition ways and the raio of Si to carbon on the size, morphology, structure and lithium storage propeties of the composites are explored. The study is specially focused on ion migration, charge transport and lithium insertion/extraction mechanism of composites as lithium storage materials, and reveals the relationship between structure and property. The optimized structural model with the best performancis is obtained. Meanwhile, the synergetic effect of components of composite materials on lithium storage performance is explored. The implementation of this subject will open up new technology of controllable preparation of carbon materials and their composites, and establish the material basis for the development of high-performance lithium ion batteries.

动力学稳定的纳微电极材料的制备是当前储锂材料研究的核心问题之一。申请课题提出以Suzuki偶合及接枝共聚等方法制备的交联聚合物为碳的前驱体，构筑动力学稳定的新材料- - 互穿网络结构的硅/碳复合材料。利用制备的交联聚合物基碳材料稳定的结构、良好的应力缓冲性、三维的导电通道、短的离子迁移路径等优势，来缓解硅电极在嵌脱锂过程中粉化、固体电解质膜破损、离子/电子传输速度慢等所导致的容量、倍率特性和寿命大幅降低的问题。考察聚合物结构、炭化工艺、复合方式、硅碳比等对材料形貌、结构和锂储能性能的影响。重点研究复合电极的离子迁移、电荷传递和脱嵌锂机制，揭示材料的构效关系，优化出硅碳复合材料性能最佳的结构模型，同时探讨复合材料各组分的协同效应对锂储能性能的影响规律。课题的实施将开拓碳材料及其复合结构的可控制备新技术，为开发高性能的锂离子电池奠定材料基础。

项目采用接枝共聚法、化学氧化聚合法、种子模板法等合成了一系列具有0维、一维或三维纳米结构的聚合物（聚苯胺球，聚苯胺和聚吡咯纤维、交联聚苯胺网、互穿网络结构水凝胶接枝共聚物），通过炭化、活化处理，获得了高比表面积的多孔炭材料。进一步，通过原位聚合法或与炭化工艺、镁还原等结合制备了硅/聚苯胺和硅/炭复合物。通过扫描电镜、透射电镜、红外、X射线衍射、X射线光电子能谱、拉曼光谱、N2吸脱附、循环伏安、恒流充放电、交流阻抗等，表征了材料的形貌、组成、结构、孔特性，评价了其电化学性能。探索了聚合物特殊形貌的合成方法及形成机理，考察了镁还原对硅复合物结构及其中硅含量的影响。考察了聚合物结构、炭化工艺、硅碳比等对材料形貌、结构、炭材料的电容性能、复合物的储锂性能的影响，揭示了复合物的离子迁移、电荷传递、脱嵌锂机制、各组分的协同效应以及材料的构效关系。与此同时，开展了硅电极表面凝胶修饰和交联型粘接剂使用的研究工作。结果表明：柔性的纳米结构的多孔聚合物及其聚合物基炭能够提供三维的导电通道、短的离子和电子传输路径、良好的应力缓冲作用；电极表面的凝胶层和交联型粘接剂能够缓冲硅体积膨胀所产生的应力，因此有效的促进了硅电极在锂离子电池中的倍率特性和循环稳定性。完成了项目计划的研究内容。. 项目执行期间，在国内外学术刊物上共公开发表13篇，其中SCI论文10篇。在人才培养方面，已毕业和正在培养的研究生共8人。获新疆维吾尔自治区自然科学优秀论文奖二等奖和新疆大学第一届自然科学奖一等奖。达到了项目预期的目标。