Anion Defect Chemistry for Advanced Battery Materials

先进的锂离子电池（LIB）是可再生能源大规模储能的最有前途和最现实的候选者之一。为了大规模使用LIB，需要改进阴极活性材料（CAM）的低比容量和短寿命。因此，开发高能量密度和鲁棒的CAM至关重要。阳离子改性是一种被广泛接受的改善电池性能的策略，然而这种常规策略正在接近其局限性。对于利用负离子功能的电池材料的进展，建立负离子缺陷工程的基本理解是至关重要的。因此，本计画的目标是建立电池CAMs的负离子缺陷化学，并为混合负离子CAMs的发展提供指引。为了实现这一目标，联合团队将通过本项目开展两个研究课题：1）揭示氧缺陷的形成机理及其对电池性能的影响。2）引入杂阴离子缺陷并研究阴离子缺陷的功能。显然，缺乏对电池CAM中阴离子缺陷物种的基础知识阻碍了基于阴离子混合策略的先进电池材料的进展。本工作的意义在于建立了负离子缺陷化学的基础科学，为电池材料的负离子缺陷工程提供了科学依据，为高能量密度和高强度的电池材料提供了合理的指导。虽然这是一个非常具有挑战性的课题，但互补的联合方法可以通过结合我们独特的方法为实现这一目标铺平道路;日本团队将评估和控制电池CAM中的阴离子缺陷物种，德国团队将评估阴离子/阳离子扩散动力学并揭示阴离子缺陷对电化学充电/放电反应的影响。两支球队在各自领域都拥有出色的记录。为了建立CAMs的阴离子缺陷化学，我们将在本项目中解决两个问题：一是建立氧缺陷化学，另一个是理解电池CAMs中杂阴离子缺陷的功能。

Advanced lithium-ion batteries (LIBs) are one of the most promising and realistic candidates for large-scale energy storage from renewable energies. For a large-scale use of LIBs, the low specific capacity and short lifetime of the cathode active material (CAM) need to be improved. Therefore, developing high-energy-density and robust CAMs is vitally important. Cation modification is a widely accepted strategy to improve battery performance, yet this conventional strategy is approaching its limitation. For the progress of battery materials utilizing anion functionality, establishing fundamental understanding of anion defect engineering is of key importance. Therefore, the goal of this project is establishing anion defect chemistry for battery CAMs and provide guidelines for the development of mixed-anion CAMs. To achieve this goal, the joint team will work on two research topics through this project:1) Revealing the oxygen defect formation mechanism and their impact on battery performance.2) Introduction of hetero-anion defects and the investigation of anion defect functionality.Clearly, lack of fundamental knowledge on anion defect species in battery CAMs impedes the progress of advanced battery materials based on anion mixing strategy. The significance of this work is establishing the fundamental science of anion defect chemistry, for anion defect engineering of battery materials which will result in rational guidelines for high-energy-density and robust battery materials. Although this is a very challenging topic, the complementary joint approach can pave the way to this goal by combining our unique methodologies; the Japanese team will evaluate and control anion defect species in battery CAMs, and the German team will evaluate anion/cation diffusion kinetics and reveal the impact of anion defects on electrochemical charge/discharge reactions. Both teams have excellent track records in their respective fields. For the establishment of anion defect chemistry for CAMs, we will tackle two problems in this project: One is to establish oxygen defect chemistry, and the other is the understanding of the functionality of hetero-anion defects in battery CAMs.