With the rapid development of electric vehicles, power batteries as core components have their performance and lifespan directly related to vehicle safety and user experience. In 2025, if the heat generated during charging and discharging cannot be effectively managed, it will lead to performance degradation and thermal runaway accidents. Therefore, the design of power battery thermal management systems has become a key breakthrough in technology.
This article will deeply analyze the technical framework of power battery thermal management from three dimensions: system classification, core functions, and implementation principles. It will sort out the collaborative mechanisms of the three subsystems: cooling, heating, and insulation, explore how to create the optimal working temperature range for batteries, and reveal the core role of temperature equalization in suppressing local hot spots and extending battery life.
Whether it's the simplicity and efficiency of air cooling, or the precise control of liquid cooling and phase change cooling, each technical path provides solutions for the "constant temperature protection" of batteries.
Power Battery Thermal Management System Classification
According to different classification standards, power battery thermal management systems can be mainly divided into the following categories:
By Cooling Mode
Divided into passive cooling systems and active cooling systems.
By Heat Transfer Medium
Divided into air cooling systems, liquid cooling systems, and phase change cooling systems.
By Function Application
Divided into cooling systems, heating systems, and insulation systems.
Structure and Functions of Power Battery Thermal Management Systems
The main functions of power battery thermal management systems include:
1. High-Temperature Heat Dissipation
When battery temperature is too high, perform effective heat dissipation to prevent thermal runaway accidents.
2. Low-Temperature Preheating
Preheat the battery at lower temperatures to increase battery temperature and ensure charging/discharging performance and safety in cold conditions.
3. Temperature Equalization
Reduce temperature differences within the battery pack, suppress the formation of local hot spots, prevent rapid degradation of batteries at high-temperature positions, thereby improving the overall lifespan of the battery pack.
Power battery thermal management restricts, regulates, and utilizes the internal thermal environment of the battery system. Its core purpose is to make the power battery work in the optimal temperature range, fully utilize battery performance, while providing an energy balance environment to achieve comprehensive utilization of vehicle energy.
Specifically, thermal management involves cooling when the battery system temperature is too high, heating when the temperature is too low, and insulating the system during special processes such as standby.
Basic Components and Functions of Cooling Systems
The cooling system is the most important component of the power battery thermal management system.
Limited by current technological bottlenecks, the working temperature environment of power batteries needs to meet specific requirements. Taking lithium iron phosphate batteries as an example, their general ambient temperature is -20°C to 60°C. During charging and discharging, the battery continuously generates heat, which can easily cause the internal temperature of the system to exceed this range, so a cooling system is usually required.
Air Cooling Systems
- Simple structure and low cost
- Suitable for low to moderate power applications
- Limited cooling capacity for high-density batteries
- Widely used in entry-level EVs
Liquid Cooling Systems
- Higher cooling efficiency
- Better temperature uniformity
- More complex structure and higher cost
- Common in mid to high-end EVs
Phase Change Cooling
- Highest cooling capacity
- Excellent temperature control
- Most complex and expensive
- Emerging technology with limited adoption
By cooling medium, cooling systems can be divided into air cooling, liquid cooling, and phase change cooling. Their cooling capabilities increase in sequence, and system structure complexity and cost also increase accordingly. In 2025, considering cost reduction factors, air cooling and liquid cooling solutions are still widely used in engineering technology.
By working mode, cooling systems are often divided into active cooling and passive cooling. Passive cooling systems have simple structures, fewer components, and lower costs, and are still widely used in battery cooling design.
A complete cooling system should include the following core components:
- Cooling power components: Mainly fans for air cooling systems; pumps for liquid cooling systems.
- Heat exchange components: Such as heat sinks, cooling plates, etc.
- Heat conduction components: Such as thermal conductive silicone grease, thermal pads, etc.
- Control components: Such as temperature sensors, controllers, etc.
Basic Components and Functions of Heating Systems
The heating system is also a key part of power battery thermal management.
In low-temperature environments, battery activity decreases, and lithium dendrites may precipitate, affecting safety and performance. Therefore, the battery system needs to introduce a heating system. Mainstream heating technologies in 2025 include liquid heating, heating films, and PTC heating, etc.
PTC Heating
Positive Temperature Coefficient heaters provide rapid heating with precise temperature control, commonly used in modern EVs.
Liquid Heating
Uses heated coolant circulated through the battery pack, often integrated with the cabin heating system.
Heating Films
Thin, flexible heating elements attached directly to battery cells for localized heating.
Basic Components and Functions of Insulation Systems
The insulation system has some functional similarities with the heating system but is strictly different.
The insulation system is more used to maintain the internal temperature of the battery system within the normal range in the short term. For example, when an electric vehicle is temporarily parked in winter and needs to work again after 2 hours, it relies on the insulation system to prevent the internal battery temperature from dropping too quickly.
Insulation system design usually uses insulation materials or thermal insulation coatings to isolate and prevent the internal temperature of the battery system from dissipating too quickly.
2025 Technology Summary and Future Outlook
Through the dynamic coordination of cooling, heating, and insulation functions, the power battery thermal management system builds a "temperature firewall" for battery safety.
- Cooling systems gradually improve heat dissipation capacity through air cooling, liquid cooling, and phase change cooling to address high-temperature risks.
- Heating systems activate battery activity at low temperatures through PTC, liquid heating, and other technologies.
- Insulation systems use material insulation characteristics to provide temperature buffering for short-term parking scenarios.
Its core value lies not only in preventing thermal runaway or lithium dendrite formation but also in maximizing battery performance potential by reducing temperature differences between cells and achieving efficient recycling of vehicle energy.
In 2025, in the balanced optimization of material costs and structural complexity, liquid cooling and air cooling remain the mainstream choices, while cutting-edge technologies such as phase change cooling continue to break through. In the future, the intelligence and integration of thermal management systems will become key engines driving electric vehicles toward higher safety and energy efficiency.
Frequently Asked Questions
Most lithium-ion batteries perform optimally between 15°C and 35°C (59°F to 95°F). Outside this range, battery efficiency decreases, and outside the -20°C to 60°C range, permanent damage can occur. Thermal management systems work to maintain batteries within this optimal range.
Proper thermal management can extend battery lifespan by 20-30%. High temperatures accelerate chemical degradation, while low temperatures increase internal resistance and can cause lithium plating. Maintaining optimal temperature and minimizing temperature variations between cells significantly reduces degradation rates.
Active thermal management uses powered components like pumps, fans, or heaters to control temperature, providing precise control but consuming energy. Passive systems rely on natural convection, conduction, or phase change materials without external power, offering simpler, more reliable but less precise temperature control.
Temperature variations between cells cause uneven aging and capacity loss. Cells at higher temperatures degrade faster, reducing overall pack capacity. Temperature differences also lead to balancing issues during charging and discharging, potentially causing some cells to operate outside safe voltage ranges.
Key trends include: integration with vehicle climate control systems, use of artificial intelligence for predictive thermal management, development of more efficient phase change materials, implementation of direct cooling technologies that contact cells directly, and the use of refrigerant-based cooling systems for ultra-fast charging applications.
Air cooling is the most cost-effective but offers limited performance for high-power applications. Liquid cooling provides excellent performance at moderate cost and is currently the industry standard for most EVs. Phase change cooling offers the highest performance but at significantly higher cost, making it suitable primarily for premium vehicles and high-performance applications.
