2D/1D nanocomposites for energy storage applications

本研究计划的目的是制备和研究用于储能应用的一维和二维（1D/2D）纳米材料的混合电极，如Li/ na离子电池。为此，过渡金属六硫代和六硫代二磷酸盐（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报道的离心技术来选择尺寸，这将使用碳纳米管制备不同尺寸的二维纳米材料（一维）的复合材料成为可能。为了在器件应用中竞争性地使用纳米材料或纳米复合材料，有必要了解和利用单个化合物之间的协同效应。为了使高性能电极的开发合理化，需要系统地研究对电极性能的不同影响，如纳米颗粒的大小和厚度、一维/二维混合比、插层化合物等。为此，为了研究一维/二维相互作用的几何影响，必须针对不同尺寸和厚度的二维纳米薄片，测试一维和二维纳米材料之间的不同混合比例。这些研究将在一个模型系统（Ni2P2S6）上实施，申请人在之前的剥离实验中对其进行了分析。制造的阳极将在实验锂离子电池和钠离子电池中实施，并分别通过显微镜和光谱学以及充放电循环前后的机械和电子实验进行表征。这样的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离开来，这将有助于优化电极结构，以及识别和预防促进材料降解的影响。从这些结果中获得的知识将用于在储能装置中实现和研究其他M2P2Ch6 （M =过渡金属，Ch =硫属化物）物种。而对于其他化合物，必须执行类似Ni2P2S6电极的繁琐测量，完整的表征对于固体基准测试和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系统的电极性能非常重要。这将有助于合理地确定新型高性能纳米复合材料电极的理想候选材料。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加工条件下的稳定性，这将对降解过程有更深入的了解，并能够找到如何防止它们的策略。为此，分别研究充电前后的电极形态、化学成分和性能将是非常重要的。

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.