2D/1D nanocomposites for energy storage applications

本研究方案的目的是制备和研究一维和二维(1D/2D)纳米材料的混合电极，用于储能应用，如锂/钠离子电池。为此，过渡金属六硫代和六硒二磷酸(2D)将在惰性气体条件下进行液相剥离。所得到的分散体将通过已报道的离心法进行尺寸选择，这将使得能够制备不同尺寸的2D纳米材料与碳纳米管(1D)的复合材料。为了在设备应用中竞争使用纳米材料或纳米复合材料，有必要了解和开发单个化合物之间的协同效应。为了合理开发高性能电极，需要对纳米粒子的尺寸和厚度、一维/二维混合比、插层化合物等对电极性能的不同影响进行系统的研究，为此，必须针对不同尺寸和厚度的二维纳米片测试一维和二维纳米材料之间的不同混合比例，以研究几何效应对一维/二维相互作用的影响。这样的研究将在一个模型系统(Ni2P2S6)上实现，申请人在之前的剥离实验中对该系统进行了分析。制作的阳极将在实验锂离子电池和钠离子电池全电池中实现，并分别在充放电循环实验前后进行显微镜和光谱表征，以及机械和电子学表征。这些实验将能够将加工过程中发生的材料分解与设备操作产生的影响分开，这将有助于电极结构的优化，以及对促进材料降解的影响的识别和预防。这些结果将用于实施和研究储能设备中的其他M2P2CH6(M=过渡金属，CH=硫化物)物种。对于其他化合物，必须进行与Ni2P2S6电极类似的繁琐测量，但完整的表征对于固体基准测试以及进一步研究和了解不同材料性质对插层化学的影响以及这种独特的同构材料体系的电极性能是重要的。这将使人们能够合理地确定新型高性能纳米复合电极的理想候选者。在惰性气体条件下进行的实验将在环境条件下重复进行，以研究电极在现实和工业相关工艺条件下的稳定性，这将使人们对退化过程有更深入的了解，并能够找到防止退化的策略。为此，分别在充电循环前后研究电极的形态、化学组成和性能将是重要的。

The aim of this research proposal is to prepare and to study hybrid electrodes of one- and two-dimensional (1D/2D) nanomaterials for energy storage applications, such as Li/Na-ion batteries.To this end, liquid phase exfoliation of transition metal hexathio- and hexaseleno-diphosphates (2D) is going to be performed in inert gas conditions. The resulting dispersion will be size-selected by reported centrifugation techniques which will enable to prepare composites of different sizes of the 2D nanomaterial with carbon nanotubes (1D). For a competitive use of nanomaterials or nanocomposites in device applications, it will be necessary to understand and to exploit synergistic effects between the individual compounds. Systematic studies on the different impacts on the electrode performance such as i.a., the nanoparticle size and thickness, 1D/2D mixing ratio, intercalation compound, will be required in order to rationalise the development of high-performance electrodes.For this purpose, different mixing ratios between the 1D and 2D nanomaterial have to be tested for different sizes and thicknesses of the 2D nanoplatelets in order to study geometric impacts on the 1D/2D interaction. Such studies are going to be implemented on a model system (Ni2P2S6), which was analysed by the applicant in previous exfoliation experiments. The fabricated anodes will be implemented in experimental Li- and Na-ion battery full cells and characterised by microscopy and spectroscopy, as well as mechanically and electronically before and after charge/discharge cycle experiments, respectively.Such experiments will enable to separate material decomposition occurring upon processing from effects arising from device operation, which will be helpful for optimisation of the electrode architecture, as well as for identification and prevention of effects that promote the material degradation.The knowledge gained from these results will be used to implement and study other M2P2Ch6 (M = transition metal, Ch = chalcogenide) species in energy storage devices. While for other compounds, similar tedious measurements have to be performed as for the Ni2P2S6 electrodes, the full characterisation is important for a solid benchmarking and to further study and understand the impacts of different material properties on the intercalation chemistry and thus the electrode performance of this unique isomorphous material systems. This will allow to rationally identify ideal candidates for novel high-performance nanocomposite electrodes.The experiments performed in inert gas conditions will be repeated in ambient conditions in order to study the stability of the electrodes in realistic and industrially relevant processing conditions, which will give deeper insights into degradation processes and enable to find strategies how to prevent them.To this end, it will be important to study the electrode morphology, chemical composition and performance before and after charge cycles, respectively.