It is essential to develop accurate "Battery Thermal Models" that can predict and manage the thermal behaviour of Li-ion batteries.
The Importance of Battery Thermal Models
The performance, safety, and lifespan of Li-ion batteries are closely related to their thermal management. Very high temperatures can cause thermal runaway, leading to catastrophic failures and safety hazards, while low temperatures can reduce the battery's capacity and performance. Accurate battery thermal models are crucial for predicting the battery's temperature distribution under various operating conditions, optimizing the thermal management system design, and ensuring the safety and longevity of the battery.
Types of Battery Thermal Models
There are several types of battery thermal models, each with different levels of complexity, accuracy, and computational demands. The three main categories are:
1) Lumped parameter models (LPMs)
LPMs are the simplest type of thermal models, which assume that the battery temperature is uniform across its entire volume. They are characterized by their low computational cost and ease of implementation. However, LPMs may not provide accurate temperature predictions under extreme operating conditions or in cases where the spatial temperature distribution is important.
2) Distributed parameter models (DPMs)
DPMs are more advanced models that consider the spatial temperature distribution within the battery. They usually involve solving partial differential equations (PDEs) to predict the temperature profile across the battery's volume. While DPMs provide more accurate temperature predictions, they come at the expense of increased computational complexity and longer simulation times.
3) Electro-thermal models
Electro-thermal models combine the electrical and thermal aspects of Li-ion batteries. These models consider the interactions between the battery's electrochemical behaviour and its thermal behaviour, enabling a more comprehensive understanding of the battery's performance under various operating conditions. However, electro-thermal models are the most complex and computationally demanding of the three types.
Applications of Battery Thermal Models:
1) Thermal management system design-
To design efficient and effective cooling and heating systems for batteries, ensuring that they operate within safe temperature ranges and maintaining optimal performance.
2) State of charge (SOC) and state of health (SOH) estimation-
To accurately estimate the SOC and SOH of a battery, which in turn helps in optimizing battery usage, prolonging its lifespan, and preventing premature failures.
3) Safety analysis- To predict the battery's response to extreme operating conditions, such as high current loads or elevated ambient temperatures.