锂离子电池高容量复合电极的损伤协同演化与电化学性能调控

对电极损伤行为的准确描述，优化电极参量和使用方法，实现损伤抑制，进而提升电化学性能，是高容量电池发展的迫切需求和必由路径。但目前的相关研究未能充分揭示复杂电极损伤行为的内在机理和演化规律，导致高容量电极优化方法缺乏可靠的评估手段，只能依赖实验试错。面内开裂和界面分层是高容量复合电极中最典型的两类损伤，本项目拟针对二者的协同演化及电化学性能优化展开研究。准确描述高容量复合电极面内开裂和界面分层的演化规律，揭示二者的耦合关系，对锂离子电池内在机制的理解具有重要意义。基于损伤控制调控电化学性能，对高容量电池的制备和使用也尤为关键。本项目拟通过考虑损伤造成的复合电极模量退化和动态约束，建立面内开裂和界面分层同时演化且相互耦合的电极尺度损伤模型，给出复合电极参量和充放电深度对损伤时空演化的影响规律，结合实验研究建立损伤对电化学性能影响的定量关系，提出基于损伤控制的电极性能调控方法。

Accurate description of electrode damage, optimization of electrode parameters and charge-discharge operations, suppressing damage, and consequently improving electrochemical performances are the urgent demands and key steps to the development of high-capacity lithium-ion battery (LIBs). However, currently, most related studies failed to evaluate the interactional mechanisms and complicated evolutions of damages within electrodes. As a result, optimizations of high-capacity electrodes lack reliable evaluations and therefore can only rely on experimental trials. In-plane cracking and interface delamination are the two most typical types of damage in high-capacity composite electrodes. In this project, the co-evolution of these two types of damage and the optimization of electrochemical performance in high-capacity composite electrodes are focused. Accurately describing the co-evolution of in-plane cracking and interfacial delamination and revealing the coupling between the two are of great significance for understanding the internal mechanism of high-capacity LIBs. Evidently improving electrochemical performances is also critical for manufacturing and operations of high-capacity LIBs. By considering modulus degradation and dynamic mechanical constraint caused by damages, a theory which describes the co-evolution of electrode-level damage in high-capacity composite electrodes will be established. The impacts of electrode parameters and charge-discharge operations will be investigated. Additionally, a quantitative relationship between mechanical damages and electrochemical performances will be established by connecting the theoretical results and experimental data. Consequently, based on the analysis of damages, the optimization of the high-capacity composite electrodes will be proposed.