Vacancy Engineering in Anode Materials for High-Power K-Ion Batteries

能源储存是我们这个时代的一个巨大研究热点，在应对气候变化和实现低碳经济方面发挥着至关重要的作用。这项技术将加速向电动汽车的过渡，并促进可再生能源在电网规模应用中的有效利用。如今锂离子电池（LIBs）的大规模生产导致了锂和Co的供应风险，这将使未来的英国电池行业受到外部市场和地缘政治力量的影响。目前迫切需要通过开发基于地球上丰富元素的下一代电池来摆脱对锂电池的过度依赖。K离子电池（kib）具有成本效益和环境可持续性，因为它们基于K（地壳中含量为2.09%，锂含量为0.002%）和无co系统。kib的优点是，K具有与Li最接近的还原电位（-2.92 V vs -3.04 V），并且能够可逆地嵌入石墨，这使得它有可能实现高能量密度，并直接利用现有的LIB制造设施。在实际应用中，如电网级存储中，考虑电池重量和尺寸要比考虑每千瓦时成本更重要，kib是一个非常有吸引力的选择。在我们之前对kib的研究基础上，我们的目标是开发高性能的kib，并释放kib作为下一代电池的潜力。开发kib的主要挑战是k离子的大尺寸，因为它导致k离子存储的动力学困难。本课题根据k离子动力学的时间尺度，设计电极材料的结构缺陷，实现kib的高性能。我们将研究在长时间尺度上具有k离子插入和扩散定向路径的晶体结构，这可以实现高能量密度。更重要的是，我们将研究创造氧空位的方法，这种方法可以在短时间尺度上实现快速的k离子动力学，从而实现高功率密度。同时，开发kib需要了解电极内部发生的复杂过程。我们将进行材料表征和化学分析，以了解氧空位的好处，特别是空位的空间效应，并获得急需的可逆k离子存储的基本化学性质，这是重要的，因为kib的发展仍处于起步阶段。这将为广泛改进KIB电极材料提供有希望的途径，并产生可以转移到其他能源应用的知识。该方法的新颖性与之前在kib领域中增强电荷输运的考虑有着根本的不同。项目内容如下：(1)探索钛铌氧化物（TNOs）作为一种新型的可可逆存储k离子的KIB阳极，确定有前途的材料作为OVs设计的模型材料。（ii）制造和控制位于表面或面向TNOs主体的氧空位，并研究空位对电极功率密度增强的空间效应。（iii）对有氧空位和无氧空位的阳极进行原位和非原位表征，以最好地表征、理解和解释设计结构工程上的k离子动力学。（iv）基于项目中开发的阳极（TNOs）的性能优势、低成本和环境可持续性，以及最先进的阴极（普鲁士蓝类似物），在实验室规模上展示KIB全电池原型。(v)与英国电池行业的所有利益相关者接触，并成为kib的倡导者。

Energy storage is a tremendous research focus of our time and plays a vital role in tackling climate change and enabling a low carbon economy. It is the technology that will accelerate the transition to electric vehicles and facilitate the efficient utilisation of renewable energy in the grid scale applications. Today's massive production of Li-ion batteries (LIBs) has resulted in the supply risk of Li and Co, which would place future UK battery industry subject to external market and geopolitical forces. There is an immediate need to exempt from the over-reliance on LIBs through developing the next generation batteries that are based on earth-abundant elements. K-ion batteries (KIBs) offer cost-effectiveness and environmental sustainability, as they are based on K (2.09% abundance in the earth's crust, vs. 0.002% Li) and a Co-free system. KIBs possess the advantages of K having the closest reduction potential to Li (-2.92 V vs. -3.04 V) and being able to reversibly intercalate into graphite, which makes it possible to achieve high energy density and directly utilise the existing LIB manufacturing facilities. In practical applications such as grid-level storage where considerations of cell weight and size take a back seat to cost-per-kWh, KIBs represent a very attractive candidate.Building on our previous work on KIBs, our ambition is to develop high-performance KIBs and unlock the potential of KIBs as the next generation batteries. The major challenge of developing KIBs is the large size of K-ion because it causes kinetic difficulties to store K-ion. This project presents the design of electrode materials' structural defects, in accordance with the time scales of K-ion kinetics, to achieve high performance of KIBs. We will study crystalline structures that have directional pathways for K-ion insertion and diffusion at a long-range time scale, which allows to achieve high energy density. More importantly, we will investigate the approach of creating oxygen vacancies that allows a fast K-ion knetics at a short-range time scale and therefore a high power density. Simultaneously, developing KIBs requires the understanding of the complex processes occurring within the electrodes. We will perform materials characterisation and chemical analysis to understand the benefits of oxygen vacancies, especially the spatial effect of the vacancies, and acquire much-needed clarity on the fundamental chemistry of reversible K-ion storage, which is important as the development of KIBs is still in its infancy. This will suggest promising avenues for the improvement of KIB electrode materials in a wide range and generate the knowledge that could be transferred to other energy applications. The novelty in the approach is fundamentally different from the previous considerations of enhancing charge transport in the field of KIBs. The project includes the following:(i) Explore titanium niobium oxides (TNOs) as a new type of KIB anodes to reversibly store K-ion, which will identify promising materials put through as the model materials for the design of OVs.(ii) Create and control oxygen vacancies located in the surface or towards the bulk of TNOs and investigate the spatial effect of the vacancies on the enhancement of electrode power density.(iii) Perform in-situ and ex-situ characterisations of anodes with and without oxygen vacancies to best characterise, understand and explain the K-ion kinetics upon the designed structural engineering.(iv) Demonstrate KIB full-cell prototypes in a lab scale based on the advantages of performance, low-cost and environmental sustainability of the anodes (TNOs) developed in the project and the state-of-the-art cathodes (Prussian blue analogues).(v) Engage with all stakeholders in the UK's battery industry and be an advocate for KIBs.