# Lithium-Ion Battery State of Health Estimation Based on CNN-LSTM-Attention-FVIM Health Features
); [EMAIL_ADDRESS] (Z.Y)  
[PERSON]  
2 College of Mechanical and Electrical Engineering, Ningde Normal University, Ningde 352000, China; [EMAIL_ADDRESS] (Z.Y)  
[PERSON]  
1 College of Mechanical and Electrical Engineering, Beijing Information Science and Technology University, Beijing 100192, China; [EMAIL_ADDRESS] (G.L. ); [EMAIL_ADDRESS] (G.G. ); [EMAIL_ADDRESS] (L.T. ); [EMAIL_ADDRESS] (M.G. ); [EMAIL_ADDRESS] (M.Y. ); [EMAIL_ADDRESS] (M.Y. ); [EMAIL_ADDRESS] (Z.Y)  
Z. College of Mechanical and Electrical Engineering, Ningde Normal University, Ningde 352000, China; [EMAIL_ADDRESS] (Z.Y)  
Z. College of Mechanical and Electrical Engineering, Beijing University of Technology, Beijing 100192, China; [EMAIL_ADDRESS] (Z.Y); [EMAIL_ADDRESS] (Z.Y)  
Z. College of Mechanical and Electrical Engineering, Ningde Normal University, Ningde 352000, China; 202406@ndnu. The most widely used clean energy at present is electricity. With the popularization of electric vehicles, mobile devices, and renewable energy storage systems, the importance of lithium-ion batteries in various fields has become increasingly prominent [3]. In the field of power batteries, lithium-ion batteries are core components of new energy vehicles, power tools, and electric bicycles, and their cost accounts for 30-40% of the total item cost [4; 5]. With the continuous improvement of electric vehicle range and charging technology, higher requirements are also put forward for battery technology [6]. The battery pack of electric vehicles is composed of hundreds to thousands of single cells in series, and the SOH difference between cells can lead to a decrease in energy utilization [7]. For instance, if the capacity of a single cell degrades to 70%, the effective capacity of the entire battery pack will be limited by the \"short board effect\", resulting in energy waste [8]. At the same time, for end users, overcharging, over-discharging, or local overheating of the battery may cause thermal runaway, or even fire and explosion. As the battery ages, capacity decay will also cause a significant decrease in vehicle range. SOH prediction is not only a technical indicator of battery management but also a core link between safety, economy, and environmental protection. Real-time and accurate prediction of battery SOH is essential [9]. Battery health state (SOH) is a core indicator for measuring battery performance degradation, usually defined as the ratio of the current maximum capacity or internal resistance to the initial value [10]. At present, SOH estimation methods can be divided into model-based methods and data-driven methods, which have significant differences in principles, implementation, and applicable scenarios [11]. First, the model-based method describes the internal dynamic process of the battery by establishing physical or electrochemical equations, and it uses the difference between observable external parameters (such as voltage, current, temperature) and model output to estimate the state. Its core is to associate the microscopic aging mechanism of the battery with the macroscopic behavior through mathematical modeling. There are two typical models: the electrochemical model and the equivalent circuit model. The principle of the electrochemical model is based on porous electrode theory (Pseudo-Two-Dimensional, P2D model), which describes the diffusion, insertion, or extraction process of lithium ions in positive and negative electrode materials by coupling mass conservation, charge conservation, and reaction kinetics equations [12]. Its advantage lies in accurately characterizing the internal aging mechanism of the battery (such as SEI film growth and active material loss), which is suitable for mechanism research.