Fabrication of Vertically Aligned Nanocomposite thin-films to probe lithium diffusion through the electrode/electrolyte interface

自1980年约翰·古德足够和同事们的开创性工作以来，锂离子电池已经成为为手机和笔记本电脑等电子设备供电的首选。然而，由于它们含有易燃的锂电解液，以及电极之间的锂树枝晶生长，导致短路和最终电池死亡，因此它们构成了重大的安全问题。固态电解液是传统液态电解液的替代品，由于其不可燃和抑制枝晶生长，可以克服这些问题。此外，通过正确的结构，它们具有更高的能量存储能力。然而，固态材料普遍存在电导率较低的问题，这限制了电池的性能。这可以归因于1)电极/电解液材料之间的高界面阻抗和2)结构限制的低电导率。围绕后一点的材料发现目前主导着该领域的研究。更好地了解固态电池材料之间的界面可以大大有助于提高固态电池的性能。然而，直接探测界面的实验技术有限(通常很难进行)，因为它被埋起来了，而且很小(几纳米厚)。垂直排列的纳米复合材料(VAN)薄膜可以解决这个问题，因为它们具有明显更大的界面表面积。这可能会增强固态核磁共振等实验中的信号，并允许直接探测界面。此外，由于货车的自组装特性，这些薄膜提供了一种容易形成高界面表面积的方法。该项目的最初目标将是合成和探测精心挑选的含有与固态电池相关的锂材料的VAN薄膜。在撰写本文时，还没有关于李凡电影的文献报道，因此这些研究将形成这一领域的一些初步工作。将对这些材料进行固态核磁共振研究(与剑桥Grey Group合作)，以探测界面，如果存在信号增强并允许锂离子迁移通过界面。除此之外，这些研究还将通过合成3D交叉型正负极材料来探索固态薄膜电池领域的潜在应用。

Since the pioneering work of John Goodenough and co-workers in 1980, Li-ion batteries have become the number one choice to power electronic devices such as mobile phones and laptops. However, they pose significant safety issues due to containing flammable Li electrolytes, and Li dendrite growth between electrodes causing short circuiting and eventual battery death. Solid state electrolytes, an alternative to the conventual liquid electrolytes, can overcome these issues as they are non-flammable and supress dendrite growth. Also, with the right structuring, they have potential for higher energy storage capabilities. However, solid state materials generally suffer from lower conductivities, which limits battery performance. This can be attributed to 1) high interfacial impedances between electrode/electrolyte materials and 2) low conductivities limited by structure. Materials discovery focusing on the latter point currently dominates research in the field. A better understanding of the interface between solid state battery materials could contribute significantly to enhancing the performance of solid state batteries. However, there are limited experimental techniques to directly probe the interface (which are often difficult to perform) owing to it being buried and very small (few nm thick). Vertically Aligned Nanocomposite (VAN) thin-films could address this issue, as they have a significantly larger interface surface area. This might enhance signals in experiments such as solid state NMR, and allow direct probing of the interface. Also, due to the self-assembling nature of VANs, these films offer an easy method to form high interface surface areas. The initial aims of this project will be to synthesise and probe carefully chosen VAN films containing Li materials relevant to solid state batteries. At the time of writing, there are no reported Li VAN films in literature, so these studies will form some of the preliminary work in this area. Solid state NMR studies on these materials (in collaboration with the Grey Group, Cambridge) will be performed to probe the interface and, if signal enhancement is present and allows, Li ion migration across it. Beyond this, these studies will explore potential applications within the solid state thin film battery field by synthesis of 3D interdigitated cathode/electrolyte/anode materials.