Tailoring sulfidation and derivatization of Prussian blue analogues towards electrochemically stable metal sulfides/carbon nanohybrids

先进的电池电极材料需要在纳米尺度上仔细设计。通常，即使是形态和组成的微小变化也会导致效率和稳定性的巨大变化。因此，将合成参数与材料性能和由此产生的电化学度量相关联是非常重要的。只有这样，我们才能建立一个知识平台，而不是依赖于经验的试错。金属硫化物是材料纳米工程挑战的一个很好的例子。金属硫化物由于其固有的高理论容量，作为电池电极具有巨大的潜力。然而，当在这样应用中执行时，它们面临着快速的容量下降，从而导致整体设备效率低下。这是因为它们在充放电循环过程中会经历很大的体积变化，导致颗粒聚集、电极破裂，此外还有其他影响材料稳定性的因素。此外，金属硫化物一般不导电，经常与碳添加剂结合以提高电荷迁移率。这些组分缺乏适当的相互作用或混合会导致循环过程中的导电性降低，从而阻碍电极性能。为了长期稳定、高效地利用金属硫化物的容量，必须仔细考虑材料的结构。目前，普鲁士蓝及其类似物(PBA-M[M‘(CN)6])是制备金属硫化物的前驱体。与许多金属氧化物和硫化物前驱体不同，PBA价格低廉，制备容易，对水和空气稳定。作为金属和碳源，它们可以转化为金属氧化物、多孔碳或它们之间的杂化。通过添加硫源，可以生产出孔隙率较高的金属硫化物。目前，对所产生的衍生物中的前体特征和处理参数没有一致的研究，研究往往局限于一个样品-一个处理。申请人的初步工作证明了该项目的可行性，同时也说明了合成参数与所得性质之间的复杂关系。这一建议旨在填补由PBA产生的金属硫化物的衍生化参数与电化学性质之间的联系的空白。该项目涉及在不同条件下对PBA进行系统的衍生化/硫化，对其形态、组成和结构进行了仔细的表征。通过这样做，我们将能够设计出一种PBA衍生的金属硫化物，可以满足长期稳定的电池的电极要求。这一点将通过合成控制调整衍生性质并评估其作为电池正极的电化学性能，并结合尸检分析来阐明测试中的材料变化来证明。该项目是申请人作为独立研究人员发展的一个重要里程碑。

Advanced battery electrode materials require careful design on a nanoscale. Often, even slight changes in morphology and composition result in great changes in the efficiency and stability. Therefore, it is fundamental to correlate synthesis parameters with material performance and resulting electrochemical metrics. Only by this way, we can establish a knowledge platform rather than relying on empiric trial-and-error. A great example for the challenges in nanoengineering of materials are metal sulfides. Metal sulfides have a huge potential as battery electrodes due to their inherent high theoretical capacity. However, while performing in such application, they face fast capacity drop that leads to an overall inefficient device. This is because they undergo great volumetric variation during charge/discharge cycles, causing particle aggregation, electrode cracking, besides other effects that compromise material stability. In addition, metal sulfides in general are not conductive being often combined with carbon additives to improve charge mobility. The lack of proper interaction or blending of these components result in a diminished conductivity along the cycles hindering the electrode performance. To capitalize metal sulfides capacity with a long-term stability and efficiency, material structure must be carefully considered.The present application focuses on Prussian blue and analogues (PBA - M[M’(CN)6]) as precursors for metal sulfide preparation. PBA are cheap, easy to prepare and are water and air stable, different from many metal oxide and sulfides precursors. Acting as both metal and carbon source, they can be converted into metal oxides, porous carbon or hybrids between those. By adding a sulfur source, they can produce metal sulfides with high porosity. Currently there are no consistent studies on the precursor character and treatment parameters in the resulting derivative with studies often limited to one sample-one treatment. Preliminary work by the applicant demonstrates the feasibility of the project and the same time shows the complex relation between synthesis parameters and resulting properties. This proposal aims to fill the gap of the link between derivatization parameters and electrochemical properties of metal sulfides produced from PBA. The project involves a systematic derivatization/sulfidation of PBA under different conditions, where morphology, composition and structure are carefully characterized. By doing so, we will be able to design a PBA-derived metal sulfide that can fulfill electrode requirements for a long-term stable battery. This will be demonstrated by tuning derivative properties through synthesis control and evaluating their electrochemical performance as battery cathodes in combination with post-mortem analysis to elucidate material transformations within testing. The project is an important milestone for the development of the applicant as an independent researcher.