三维多孔层状金属氧化物复合体系的可控构筑及其柔性超电容性能

Layered metal oxides with ultra high pseudocapacitance play an important role in the development of high performance supercapacitors. Based on the unique pretreatment of the raw metal oxides powders and by using environmental friendly dispersive solvents with low boiling points, such as water, ethanol, ethylene glycol, isopropanol, this project intends to develop an advanced liquid phase exfoliation (LPE) process, through which the mixed layered metal oxides and graphite powders will be simultaneously and effectively delaminated resulting in few- and mono-layered two-dimensional nanosheets. The exfoliation effect and uniform dispersion state will be systematically optimized by using reasonably matching the charge polarity, surface tension and other parameters of the composite powders and dispersants. The vacuum filtration technique and spraying coating process will be introduced for the controllable construction of three-dimensional porous layered metal oxides/graphene nanosheets composite films. The highly active nano- and meso-porous structure will be in-situ generated among the as-exfoliated nanosheets by the ultrasonic fragmentation effect during the LPE process. The interface state of the composite between the oxides nanosheets and graphene nanosheets will be further improved by using carbonization through annealing treatment in Ar atmosphere. By means of BET, FESEM and other characterization methods, the specific surface area and the three-dimensional microstructure feature of the composite film could be characterized and regulated. Based on the as-fabricated composite films, flexible supercapacitors will be assembled and furthermore, the qualitative and quantitative relationships between the composition, microstructure and supercapacitive properties will be carefully discussed. The achievement of this project will provide some theoretical basis and series of candidate electrode materials for the future development of high performance flexible supercapacitors.

具有超高赝电容效应的层状金属氧化物对于发展高性能超电容器件具有至关重要的作用。本项目拟采用目标调控的改进型液相剥离工艺，选择绿色环保型低沸点分散剂体系(水，乙醇，乙二醇，异丙醇)，结合特有的初始粉末预处理，创新地提出层状金属氧化物与少层/单层二维石墨烯纳米片的同步高效可控剥离，通过合理匹配复合粉末与分散剂体系之间的电荷极性、表面张力等参量，系统优化复合粉末各组分相应的剥离效果及均匀分散状态；引入真空抽滤和热喷涂成膜工艺，构筑三维多孔层状氧化物/石墨烯纳米片复合膜，充分利用超声破碎作用在纳米片上原位引入高活性纳米孔/介孔，通过碳化包覆改善复合膜内部界面状态，借助于BET, FESEM等表征方法反馈调控复合膜比表面积和三维微观结构；进一步组装柔性超电容器件，探明柔性超电容器件综合性能优化过程中材料成分、微观结构与性能之间的定性/定量关系，为发展新型高性能柔性超电容器件提供理论依据和材料支撑。

金属氧化物作为典型的赝电容电极材料，对于发展新型高性能的电化学储能器件，尤其是超级电容器和锂离子混合电容器具有决定性的作用。锂离子混合电容器可以有效结合锂离子电池和超级电容器的储能优势，同时实现高能量密度、高功率密度和长循环寿命。提高锂离子混合电容器性能的关键在于开发具有快速存储锂离子能力的负极材料来平衡两电极之间的动力学差异。本项目基于金属氧化物，尤其是层状金属氧化物的复合材料体系，进一步引入液相剥离制备工艺实现了超薄二维材料纳米片及其量子点的可控剥离高效制备，结合项目负责人前期研究的基于柔性铜箔表面有序纳米阵列的可控构筑及其电化学储能特性研究等成果，实现了多种组分金属氧化物复合体系及氮化改性、包覆改性的电极材料的可控构筑，并进一步组装了超电容器件、锂离子混合电容器件以及锂离子电池器件，系统研究了所制备金属氧化物复合材料体系的电化学储能特性。基于改性TiO2纳米管阵列的金属氧化物复合材料，在2Ag-1的电流密度下，比电容可达1511.2Fg-1，组装的非对称超级电容器件电压窗口可扩大至1.6V，比电容可达到127.9Fg-1，在400.5Wkg-1功率密度下的能量密度可达45.5Whkg-1。基于预锂化碳包覆层状结构T-Nb2O5组装的锂离子混合电容器同时表现出高的能量密度(93.6Whkg-1)和功率密度(9981Wkg-1)。通过一种新型固相氮化工艺实现了对T-Nb2O5进行氮化改性，基于改性后NbOxNy组装的锂离子混合电容器，最大能量密度和最大功率密度分别为121.4Whkg-1 (功率密度为200Wkg-1)和10kWkg-1 (能量密度为65.8Whkg-1)。对商业粉末V2O5等进行固相氮化改性处理获得VN级相应的氮化物，证明了固相氮化工艺的普适性，为设计和合成高性能氮化物或氮氧化物提供了一条新途径。本项目对层状金属氧化物的剥离制备和复合改性处理为构筑新型高性能电化学储能电极材料及器件提供了理论依据和技术支撑。