Lithium-ion batteries are electrochemical storage devices that occupy an important place today in the field of renewable energy applications. However, challenging requirements of lithium-iron-phosphate LiFePO₄ (LFP) batteries in terms of performances, safety and lifetime must to be met for increase their integrations in these applications. It is important to identify the origins and symptoms of battery aging and to quantify the various aging modes. In this context, the aim of this paper is to develop a reliability approach which ensures the evaluation of LFP batteries aging using causal tree analysis and electrical equivalent circuit model. The causal tree enables a good understanding of common aging modes such as the loss of lithium inventory, loss of active mass, electrolyte degradation and corrosion of the current collectors and a comprehensive identification of their potential causes. The determination of electric equivalent model parameters is based on experimental voltage responses under different discharge rates and operating temperatures. This experimental study allows creating database parameters of a new battery, which takes into account the temperature effect using the fuzzy logic method. The proposed diagnostic system is based on the use of electrochemical impedance spectroscopy (EIS) technique to determine the parameters of used battery and compared them to the parameters of new battery. The comparison results allow quantifying the depth of the various aging modes as well as the number of remaining cycles. This study is completed by testing three LFP batteries that give insights into the feasibility and efficiency of the proposed diagnostic method.

锂离子电池是电化学存储设备，在当今可再生能源应用领域占据重要地位。然而，磷酸铁锂 LiFePO _{4 的}挑战性要求(LFP) 电池必须满足性能、安全性和使用寿命方面的要求，以提高它们在这些应用中的集成度。确定电池老化的根源和症状并量化各种老化模式非常重要。在这种情况下，本文的目的是开发一种可靠性方法，确保使用因果树分析和电气等效电路模型对 LFP 电池老化进行评估。因果树可以很好地了解常见的老化模式，例如锂库存损失、活性质量损失、电解质降解和集电器腐蚀，并全面确定其潜在原因。电等效模型参数的确定基于不同放电率和工作温度下的实验电压响应。该实验研究允许创建新电池的数据库参数，使用模糊逻辑方法将温度影响考虑在内。所提出的诊断系统基于使用电化学阻抗谱 (EIS) 技术来确定旧电池的参数并将其与新电池的参数进行比较。比较结果允许量化各种老化模式的深度以及剩余周期数。这项研究是通过测试三个 LFP 电池完成的，这些电池可以深入了解所提出的诊断方法的可行性和效率。所提出的诊断系统基于使用电化学阻抗谱 (EIS) 技术来确定旧电池的参数并将其与新电池的参数进行比较。比较结果允许量化各种老化模式的深度以及剩余周期数。这项研究是通过测试三个 LFP 电池完成的，这些电池可以深入了解所提出的诊断方法的可行性和效率。所提出的诊断系统基于使用电化学阻抗谱 (EIS) 技术来确定旧电池的参数并将其与新电池的参数进行比较。比较结果允许量化各种老化模式的深度以及剩余周期数。这项研究是通过测试三个 LFP 电池完成的，这些电池可以深入了解所提出的诊断方法的可行性和效率。