Exploring All-Solid-State Batteries using First-Principles Modelling: Effective Computational Strategies towards Better Batteries

储能在当今社会中的作用比以往任何时候都更加重要，并已成为我们这个时代最大的研究挑战之一。英国能源与气候变化部通过《气候变化法案》承诺到2050年将温室气体排放量减少80%，并于最近宣布投资2.46亿英镑用于储能研发。这些举措的动机是英国必须从全球向新能源和更有效的储存过渡中受益。然而，解决当前电池技术的局限性将是英国开发高性能、可持续、对环境影响小的储能技术的关键。自20世纪80年代以来，可充电锂离子电池（LIB）开创了清洁和有效的能量存储，并彻底改变了便携式电子产品。同样，LIB可以成为电动汽车和可再生能源电网规模存储发展的关键技术。然而，由于安全问题，LIB的升级并不简单。传统锂离子电池中常用的有机电解质溶液具有挥发性、易燃性，甚至爆炸性，可能导致灾难性故障，特别是当大量用于多芯电池为能源密集型应用提供动力时。随着传统锂离子电池的理论极限越来越接近，人们对下一代电池技术的需求也越来越大，以满足严格的能源需求。通过用固体等效物取代有机电解质溶液，全固态电池（ASSB）不仅可以缓解这些安全问题，而且由于其更高的能量密度，还可以提供上级电池性能。这使得ASSB非常适合各种行业中具有挑战性的应用，无论是小型（芯片或传感器上的电池），中型（电动汽车）还是大型（可再生能源的电网级存储）。然而，在ASSB完全商业化之前，仍需要解决三个主要挫折：（1）与传统电池相比，当前ASSB组件的性能有限;（2）固体电解质和电极之间的化学、电化学和机械不相容性;（3）全球锂储量有限，随着锂离子电池需求的增长，电池单位成本也在增加。ASSB的全部潜力将成为下一个-通过发现与当前技术相比具有上级特征的新电池材料，例如更高的能量密度、更快的充电速率、更安全的操作、更好的组件兼容性和更低的价格，可以解锁第二代电池。基于实验室的试错，实验材料的发现既昂贵又耗时：必须在实验室中合成并稳定新材料，然后才能评估其作为电池组件的效率。计算建模工具可以通过从头开始预测新材料，并通过提供基于计算机的实验来表征新材料，补充物理实验，来帮助加速这种试错过程。在这个框架内，该项目的主要目标是使用自下而上的方法改进全固态电池技术，通过使用计算建模在原子水平上解决这些主要限制。这一目标将通过解决三个目标来实现：（1）发现具有上级性能的新型ASSB材料，即新的固态电解质和适用于锂离子和超越锂离子（例如钠和钾）电池技术的电极。(2)在ASSB内设计更好的固体电解质-电极界面，以增强其机械和电化学稳定性。(3)合理设计ASSB组件的镀膜策略，以增强组件之间的兼容性。

Energy storage has a more central role in our society today than ever before and has become one of the greatest research challenges of our time. The UK's Department of Energy & Climate Change has committed to the green-house gas emission reduction of 80% by 2050 through the Climate Change Act and has recently announced an £246-million investment in energy storage R&D. Such moves are motivated by the necessity for the UK to benefit from what is a global transition to new energy sources and more effective storage. However, solving the limitations in the current battery technologies will be key in order for the UK to develop high-performance, sustainable energy storage with low environmental impact. Since the 1980s, rechargeable Lithium-ion batteries (LIBs) have pioneered clean and effective energy storage and revolutionised portable electronics. Similarly, LIBs can be the key technology for the development of electric vehicles and grid-scale storage of renewable energy. The upscaling of the LIBs is, however, not straightforward due to safety issues. Organic electrolyte solutions -commonly used in the conventional Li-ion batteries- are volatile, flammable and even explosive, potentially causing catastrophic failures, specifically when used in substantial amounts in multi-cell batteries to power energy-intensive applications. As we near the theoretical limits of conventional Li-ion batteries, there is an ever-growing need for next-generation battery technologies that can meet the stringent energy demand.By replacing the organic electrolyte solutions with solid equivalents, all solid-state batteries (ASSB) can not only mitigate these safety issues, but also provide superior battery performances due to their higher energy density. This renders ASSBs ideal for challenging applications in various industries, on a small (battery on a chip or sensor), medium (electric vehicles) to large scale (grid-level storage for renewables). Three major setbacks, however, still need to be addressed before ASSBs can be fully commercialised: (1) the limited performance of the current ASSB components compared to traditional battery ones; (2) chemical, electrochemical and mechanical incompatibilities between the solid electrolytes and electrodes; (3) globally limited Li reserves, increasing the battery unit costs whilst demands for Li-ion batteries are growing.The full potential of ASSBs as next-generation batteries can be unlocked by the discovery of new battery materials with superior features compared to current technology, such as higher energy densities, faster charge rates, safer operation, better component compatibility and lower prices. Based on lab-based trial-and-error, the experimental materials discovery can be both expensive and time consuming: a new material must be synthesised and stabilized in the lab before its efficiency as a battery component can be assessed. Computational modelling tools can help accelerate this trial-and-error process both by predicting novel materials from scratch and by providing computer-based experiments to characterize the novel materials, complementing the physical experiments.In this framework, the main goal of this project is to improve all-solid-state battery technology using a bottom-up approach by tackling these primary limitations at an atomic level using computational modelling. This goal will be achieved by addressing three objectives:(1) To discover novel ASSB materials with superior performance, namely new solid-state electrolytes and suitable electrodes for the Li-ion and beyond Li-ion (e.g. sodium and potassium) battery technologies.(2) To engineer better solid electrolyte-electrode interfaces within ASSBs to augment their mechanical and electrochemical stability.(3) To rationally design ultrathin film deposition strategies to coat ASSB components to augment their compatibility with each other.