三维石墨烯包覆纳米硅复合材料在柔性储能器件中的应用

Pulverization of electrode materials and loss of electrical contact have been identified as the main causes for the performance deterioration of alloy anodes. Based on the combined magnesiothermic reduction and ice-templating freeze-drying methods, in this project, we aim to realize the hierarchical arrangement of spatially confining silicon nanocrystals within an oriented macroporous graphene monolith for alleviating these issues. Additionally, a film-like flexible full battery will be assembled through integrating the graphene/Si anode with nanocellulose membrane separator and lithium iron phosphate cathode via a simple slurry-casting procedure. Our project targets to simultaneously realize the optimal energy/power densities, coulombic efficiency, cycle life, mechanical strength in the flexible energy storage device. Synchrotron-based photoemission spectroscopy and operando XRD will be employed in the investigation of the lithiation process of silicon. This study only not opens the avenue for graphene's application in the surface modification of silicon anodes , but also directs the rational structural design of the flexible energy storage devices.

电极的粉化和电接触的衰减问题一直以来都被认为是络合类锂电负极材料性能衰减的主要原因。本项目基于镁热还原法和冷冻干燥的复合技术，目标合成出保留有预留孔结构的石墨烯包覆的硅颗粒的三维自支撑结构以解决上述问题。另外，实验还设计通过与纸浆涂层类似的涂覆方法，将上述硅碳复合负极材料，磷酸铁锂正极材料与改性的纳米纤维素隔膜构建出一种高性能的柔性全电池。本项目的目标在于实现柔性储能器件在能量密度，倍率性能，库伦效率，循环周期，以及机械强度的同步优化。同步辐射光电子能谱分析技术 (SRPES)和operando X射线衍射相变分析技术也将被用在硅材料锂化过程中的机理研究。这一研究项目不但拓展了石墨烯在改性硅负极材料的应用范围，并为高效的柔性储能器件的设计提供新的方向。

随着工业和电子信息技术的快速发展，人们对于能量存储系统的能量密度、输出功率和耐极端条件提出了更高的要求。目前以锂离子电池为代表的储能系统在机械弯折、高温储存和关键材料的全电池优化匹配上还存在短板。因此，设计与构筑新型储能材料，提升集成系统在特殊的热、电、力环境下工作的可靠性与安全性，具有重要的科学意义和实用价值。研究内容包含明晰关键电极材料在高温/机械负载/极端充放电条件下的结构构型、表界面属性、体相属相以及电化学性能的影响机制，发展了多种关键正、负极材料微/纳结构设计的跨尺度制造工艺，建立透射模式的原位表征技术在特殊电池操作环境应用方法。