锂离子电池衰减机理模型研究

Attenuation Mechanism Simulation of Lithium Batteries

摘要: 如今在电动汽车领域，锂离子电池在能源供给方面起到了不可获取的作用，其中三元电池因其高能量密度也是应用广泛，但是高能量密度同时也带来了安全方面的隐患。为了深入研究不同滥用工况对三元锂离子电池在老化过程的影响，以指导三元电池长寿命管理策略。本文基本三元18,650圆柱电池开展了正常老化工况实验，以及不同滥用工况实验。分别从容量外特性角度以及衰减机理内特性角度分析滥用工况与正常老化工况的区别，并建立了双水箱模型，仿真辨识电池内部老化参数，分析电池衰减机理以及老化路径。最终发现滥用工况均会导致电池容量衰减加速，不同滥用工况下老化路径也有所区别。根据容量衰减情况以及老化路径分析结果，将三元电池应该避免的滥用工况先后进行排序：低温 > 过充 > 高温 > 大倍率放电 > 大倍率充电。研究成果为三元锂离子电池合理使用工况设计提供了参考与基础。

Abstract: Nowadays, in the field of electric vehicles, lithium-ion batteries play an inaccessible role in energy supply, in which ternary batteries are widely used because of their high energy density, but the high energy density also brings safety concerns. In order to investigate the impact of different abusive operating conditions on the aging process of ternary lithium-ion batteries, with the aim of guiding long-term management strategies for these batteries, this study conducted experiments on normal aging conditions and different abusive operating conditions (overcharging, high-rate charging/discharging, high/low temperature cycling) using basic ternary 18,650 cylindrical cells. The differences between abusive operating conditions and normal aging conditions were analyzed from the perspective of external characteristics such as capacity and internal characteristics related to degradation mechanisms. The dual-tank model was employed to identify battery aging parameters and analyze the degradation mechanisms and aging paths. It was ultimately discovered that all abusive operating conditions accelerated capacity decay, and different abusive operating conditions also exhibited variations in aging paths. Based on the analysis of capacity decay and aging paths, a ranking of the abusive operating conditions to be avoided by ternary batteries was established as follows: low temperature > overcharging > high temperature > high-rate discharging > high-rate charging. This research provides a reference and foundation for the rational design of operating conditions for ternary lithium-ion batteries.