具有介孔电解质膜通道的Sn基核壳电极材料的设计及其低温嵌锂性能研究

Serious polarization and surface lithium plating of anode materials under low temperature seriously limit the application of Lithium-ion batteries in a cold environment. The poor dynamic process of lithiation at low temperature is the essential reason causing this problem. In this proposal, a special kind of Yolk-Shell type Sn@void@meso-C anode material with mesoporous electrolyte membrane channels in the cycling process is successfully designed from the perspective of surface chemistry and spatial structure which influence the lithiation dynamic process. Based on this model material with controllable surface and spatial structure, the influence of physicochemical characteristics of materials on the surface reaction and internal transfer efficiency of lithium during the low-temperature lithiation process will be systematically studied. The organic connection between the characteristic structures including the core size, cavity volume and mesoporous shell of the material and its lithiation dynamic behavior will be illuminated. Through the modification of mesoporous membrane channels, the basic rule about electrochemical characteristics of membrane channels influencing on the surface reaction and transfer behavior of lithium ion will be investigated. A comprehensive research and control method of low-temperature lithiation dynamic mechanisms of anode materials will be formed. This project will deepen the understanding of key influence factors and the corresponding essential rule of low-temperature lithiation behavior and also provide scientific basis for the development of novel high performance anode materials for low-temperature application of Lithium-ion batteries.

负极材料低温下的严重极化和表面析锂现象严重限制了锂离子电池在寒冷环境的应用，材料低温嵌锂过程的动力学受限是这一问题的本质原因。本项目从影响材料嵌锂动力学的表面状态及空间结构角度出发，设计了一种在循环过程中具有特殊介孔电解质膜通道的Yolk-Shell型Sn@void@meso-C负极材料。通过这种表面及空间结构能够有效调控的模型材料，系统的研究材料物化特性对低温嵌锂过程中锂离子表面反应和内部传输效率的影响，阐明材料的内核尺寸、空腔体积以及壳层介孔孔道等结构特性与嵌锂动力学行为之间的有机关联。通过材料介孔膜通道改性方案，探究膜通道电化学特性变化影响锂离子传输和表面反应行为的基本规律，形成全面的负极材料低温嵌锂动力学机制研究和控制方法。本项目对理解负极材料低温嵌锂动力学行为的关键影响因素及其本质规律有一定的理论意义，同时也有望为新型低温适用锂电负极材料的结构设计和性能优化提供相应的科学依据。

作为现阶段储能装置的主流选择，锂离子电池电极材料低温下的严重极化和表面析锂现象严重限制了其在寒冷环境的应用，而负极材料低温嵌锂过程的动力学受限是这一问题的本质原因。本项目从影响材料嵌锂动力学的表面状态及空间结构角度出发，设计并成功合成了多种Sn基碳复合材料用于低温嵌锂负极材料理论研究及应用探索。其中，利用液氮猝冷自组装方法制备了SnO2/单分散石墨烯复合材料，其呈现极为均匀的单分散状态，活性组分与载体结合紧密，获得了极高的倍率性能和大电流下优异的循环性能，同时其钠电循环性能也获得了证实；利用球磨后焙烧法获得了聚苯胺碳@Sn/膨胀石墨复合材料，聚苯胺自身作为导电聚合物同时通过适度焙烧进一步提高了导电性，同时产生的碳包覆层成功抑制的Sn颗粒的聚集长大，取得了低温（-20oC）下260 mAh/g以上的储锂容量；还利用一步络合液相还原的方法成功制备出Sn/石墨烯低温嵌锂复合材料，其成功的解决了常规高温还原Sn导致的Sn颗粒长大问题，取得了322 mAh/g的稳定低温嵌锂容量，同时对Sn活性组分分散及载体协同作用对低温嵌锂特性影响的规律进行了深入研究。本项目的开展及相应论文成果的发表，对锂离子电池低温嵌锂材料的开发提供了一定的理论指导意义并具有一定的潜在应用价值。