利用锂电池进行大规模的电能存储必须依赖电池成组，然而电池组的寿命却远小于单体寿命。针对电池组寿命快速衰退的问题，本项目拟围绕电池组系统寿命衰退机理，通过电池组加速寿命实验设计，结合电池组建模和单体寿命衰退机理开展研究工作。首先，通过建立面向状态估计的电池组分频模型实现电池组建模的频率解耦，有望精确快速估计电池组及组内单体状态，支持电池组寿命衰退机理的辨识研究。其次，研究电池组区别于单体寿命衰退的特征影响因素，从寿命二维衰退的新角度研究电池组寿命的衰退过程，探索电池组一致性和耐久性低频交互耦合作用机制下的系统动力学寿命衰退机理，有望深入了解电池组寿命衰退机理，回答电池组寿命远小于单体寿命的原因。最后，基于电池组寿命衰退机理，研究单体制造差异对不同电池组构型的寿命影响。研究结果将丰富电池组寿命衰退机理的理论认识，同时可从提高电池组寿命的角度提出电池单体的设计方向并指导电池组的成组设计。

Large-scale electric energy storage using Lithium-ion batteries depend upon battery packs. Unfortunately, life of a battery pack is always far shorter than that of a single cell. Hence, by designing accelerated battery pack life tests, establishing battery pack models and understanding single cell aging mechanisms, this project intends to focus on the battery pack aging mechanisms. Firstly, through the establishment of frequency division battery pack models for state estimation, battery packs can be modelled in decoupled frequency domains. The frequency division battery pack models are expected to quickly and accurately estimate the states of the battery packs which would support the investigation of battery pack aging mechanisms. Secondly, the unique factors of pack aging that is different from single cell capacity fade are studied. Battery pack aging processes and mechanisms are investigated from a new perspective of two-dimensional aging mechanism. System dynamics battery pack aging mechanism is to be explored with respected to the low frequency interactions of the cell variations and pack durability. Reasons why life of a battery pack is shorter are expected to be discovered with detail battery pack aging mechanisms. Finally, based on battery pack aging mechanism, the influences of the manufacturing quality on different battery pack configurations will be discussed. The findings will enrich the theoretical understanding of battery pack aging mechanisms and are expected to provide theoretical guidance for the design of single cells and battery pack construction from the perspective of improving battery pack life.