Two-dimensional nanomaterials for the development of flexible batteries

在21世纪，随着无线技术的普及和减少对化石燃料依赖的愿望的增长，对制造更好的电池的需求也在增加。随着电子产品的普及，便携性和可穿戴性已成为消费者最关心的问题。因此，轻便、高效、高密度和机械通用的储能装置已成为时代的需要。消费电子市场由便携式设备主导；无论是智能手机、笔记本电脑，还是可穿戴设备（智能手表、耳机、VR耳机、健身监测器等）：每一种设备都依赖于锂离子电池。此外，柔性电池越来越需要的新技术，如卷式显示器或透皮给药系统。不幸的是，就目前的情况来看，尽管电池是最简单的组件，但在任何电子系统中，电池往往被视为瓶颈；由于电池技术的进步不足，无线通信和电动汽车的发展停滞了几十年，由于目前电动汽车的低成本效率、高重量和相对较低的续航里程（即每次充电公里），电动汽车仍在与汽油动力汽车竞争。新型二维纳米材料的使用对于克服制造高度稳定、高效、紧凑和机械柔性的锂离子电池的挑战至关重要。同样的问题也适用于其他化学材料，如镍氢电池、钠离子电池、锂空气电池和锂聚合物电池。二维材料表现出许多独特的特征，这些特征对于下一代电池化学中柔性电极的组成是可取的；这些优点包括非常大的表面积体积比，重量轻，以及更多的插入位点，以实现锂离子的快速扩散。虽然单个纳米材料本身是有用的，但堆叠不同的纳米材料来创建稳定的异质结构将使我们能够克服每种材料的缺点。在先前的研究中，柔性石墨烯复合纳米片电极表现出优异的循环稳定性和高速率能力，使其成为下一代电极的有希望的候选者。此外，石墨烯固有的非凡载流子迁移率和抗拉强度使其在电子和机械上都特别适合这种应用。虽然先前的研究已经进行并显示出这个想法是有希望的，但大多数先前的研究都集中在单个柔性电极的制备和表征上。这将是我的努力准备一个完整的柔性电池，并为下一代电池物理学提供一个连贯的方法。此外，到目前为止，大多数研究都集中在电池级性能上，然而，我应该尝试提供2d纳米材料电池充放电过程的准确表征，并揭示其内在的优势和局限性。在我的博士学位期间，我打算为建模创建一个计算框架，随后通过实验推进电池技术，通过创造性地使用二维纳米材料，使其变得更轻、更快、更稳定、机械上更通用。如果格拉斯哥大学和詹姆斯瓦特纳米制造中心能给我这样做的机会，我将不胜感激。我也非常感谢我的导师Vihar Georgiev博士，他支持了我的博士研究申请，并指导我完成了最后一年的项目。

In the 21st century, as wireless technology has become ubiquitous and the desire to reduce our reliance on fossil fuels has grown, the need for building better batteries is also increasing. As electronics becomes pervasive, portability and wearability have become a prime concern for consumers. Consequently, light, efficient, high density, and mechanically versatile energy storage devices have become the need of the hour. The consumer electronics market is dominated by portable devices; be it smartphones, laptops, or wearables (smart watches, headphones, VR headsets, fitness monitors etc.): each device depends on Li-ion batteries. Furthermore, flexible batteries are increasingly desired for novel technologies such as roll-up displays or transdermal drug delivery systems.Unfortunately, as things stand today, despite being the simplest of components, batteries are often seen as a bottleneck in any electronic system; wireless communications and electric vehicles were held back decades due to the insufficient advancement of battery technology, and the latter continues to struggle against its petrol-powered brethren due to the low cost-efficiency, high kerb-weight, and relatively low range (i.e. kilometres per recharge) of current electric vehicles. The use of novel two-dimensional nanomaterials is crucial to overcoming the challenges of fabricating highly stable, efficient, compact and mechanically flexible Li-ion batteries. The same concerns are applicable for alternative chemistries such as NiMH, Na-ion, Li-air, and Li-polymer batteries.2D materials exhibit many unique features that are desirable for the composition of flexible electrodes in next-generation battery chemistries; these include a very large surface area to volume ratio, low weight, and more intercalation sites for fast lithium-ion diffusion. While individual nanomaterials are useful on their own, stacking different nanomaterials to create stable heterostructures would enable us to overcome the shortcomings of each individual material. In previous studies, flexible graphene-composite nanosheet electrodes have shown excellent cycling stability, and high rate capabilities making them promising candidates for next-generation electrodes . Furthermore, the inherently extraordinary charge-carrier mobility and tensile strength of graphene make it particularly suited for this application, both electronically and mechanically.While previous studies have been conducted and shown the idea to be promising, most of the priorresearch has focused on the preparation and characterization of a single flexible electrode. It will be my endeavour to prepare a complete flexible battery, and provide a coherent approach for the next generation of battery physics. Furthermore, so far most studies have focused on battery level performance, however it shall be my attempt to provide an accurate characterization of the charge/discharge processes in 2D-nanomaterial based batteries and reveal their intrinsic strengths and limitations.During my PhD, I intend to create a computational framework for modelling, and subsequently experimentally advancing battery technology, to become lighter, faster, more stable, and mechanically versatile by creatively using 2D nanomaterials. I would be grateful if the University of Glasgow and the James Watt Nanofabrication centre provide me the opportunity to do so. I am also immensely grateful to my supervisor, Dr Vihar Georgiev, who has supported my application to pursue this doctoral research, and guided me throughout my final year project.