高容量多孔合金负极材料结构稳定化设计及其增强储钠性能研究

Alloying electrode materials, such as Sn, Sb and Ge, have attracted much attention as anodes in sodium ion batteries because of their high capacities, however, they suffer from the large volume change upon cycling during the sodium alloying and de-alloying process. The large volume change always cause the pulverization of the electrode materials and the repeated broken of the solid electrolyte interphase film, thus resulting in the inferior capacity retention. In this project proposal, we are planning to construct porous structure of alloying materials, fabricate their composites with graphite-like carbon coating and the composites of intercalation type anode materials/alloying materials/graphite-like carbon. By fabricating these structures, the structural stability of the electrode materials and the electron transportation can be enhanced. Due to the good mechanical strength of the graphite carbon, the expansion of the alloying materials is limited within the porous interiors, and the destroy to the SEI film will be degraded. Moreover, the good conductivity of the graphite-like carbon is helpful for the electron transportation. Therefore, the alloying materials are expected to deliver high capacity, good rate capability and cycling stability. In order to realize the graphite carbon coating on the surface of the alloying materials, the catalysts will be firstly loaded and later facilitate the formation of graphite-like carbon from their precursors. Considering the better structural stability of intercalation-type anode materials, the structural stability of the electrode materials can be further improved by both intercalation-type anode material coating and graphite-like carbon coating and better electrochemical cycling performances are expected for sodium ion batteries.

合金负极（Sn, Sb, Ge等）具有很高的储钠容量，作为钠离子电池的负极材料被广泛研究。但是合金负极材料在电化学循环过程中体积变化大、材料容易粉化、破碎，造成电池性能的恶化。本项目通过多孔结构改造，表面后续石墨化碳催化包覆和嵌入型/合金/石墨化碳多孔材料的构筑，减少电化学储钠过程中的应力冲击，提升电极材料表面的结构稳定性和导电性能，实现多孔合金负极的内膨胀，降低对电极材料界面SEI膜的破化，提高电子传输的效率，获得优越的倍率和循环性能。本项目通过在合金负极表面进行催化剂的负载，实现对碳前驱体材料的石墨化催化包覆。结合嵌入型负极更好结构稳定性，对合金负极进行嵌入型负极和石墨化碳多级包覆，进一步提升材料的结构稳定性和循环性能。

合金负极（Sn, Sb, Ge等）具有很高的储钠容量，作为钠离子电池的负极材料被广泛研究。但是合金负极材料在电化学循环过程中体积变化大、材料容易粉化、破碎，造成电池性能的恶化。本项目通过多孔结构改造，表面后续石墨化碳催化包覆和嵌入型/合金/石墨化碳多孔材料的构筑，减少电化学储钠过程中的应力冲击，提升电极材料表面的结构稳定性和导电性能，实现多孔合金负极的内膨胀，降低对电极材料界面SEI膜的破化，提高电子传输的效率，获得优越的倍率和循环性能。本项目通过在合金负极表面进行催化剂的负载，实现对碳前驱体材料的石墨化催化包覆。结合嵌入型负极更好提升结构稳定性，对合金负极进行嵌入型负极和石墨化碳多级包覆，进一步提升材料的结构稳定性和循环性能。具体包括以下四个部分：1. 碳修饰多孔合金负极材料的构筑。采用液相沉积的方法制备多孔合金负极前驱体化合物，并研究了多孔合金前驱体化合物材料的形成过程以及合成工艺参数对产物物相、结构的影响。2.合金负极/功能化碳复合材料的制备。我们利用水热法及后续碳化、硫化处理等方法构建合金负极/功能化碳复合材料，实现合金活性电极材料与碳材料的高度纳米尺度复合。还拓展应用静电纺丝技术，构建了含碳基体的自支撑合金负极复合材料。3. 为嵌入型/合金/碳负极复合材料的制备。研究 TiO2等嵌入型负极材料与合金负极前驱体/多孔碳材料在纳米尺度的表面包覆技术，构筑了核-壳结构的嵌入型负极@合金负极复合材料。4.将上述结构设计方法，拓展到其他类型的钠离子电池负极材料（转化或者嵌入），并获得了良好的电化学性能。