Introduction
In today’s rapidly advancing new energy sector, lithium iron phosphate battery packs have become the preferred energy source for electric vehicles and energy storage systems due to their high energy density, environmental friendliness, and lack of memory effect. However, lithium-ion batteries are highly sensitive to temperature, and maintaining efficient discharge and optimal performance within an appropriate temperature range is a technical challenge. Our company is dedicated to the research and development of battery thermal management technology, and we have made significant progress, particularly in phase change cooling technology. This article compares phase change cooling with liquid and air cooling technologies, revealing this technological revolution with detailed data.
Table of Contents
- Research Background
- What is Phase Change Cooling?
- Liquid Cooling Technology: High Cooling Efficiency, But Costly and Challenging to Maintain
- Air Cooling Technology: Simple Structure, Limited Cooling Efficiency
- Our Research and Findings
- Numerical Simulation and Experimental Verification
- Conclusion and Future Prospects
Research Background
Lithium batteries generate a significant amount of heat during high-load operation. If not effectively managed, this can affect battery performance and shorten its lifespan. Traditional cooling methods, such as air cooling and liquid cooling, although effective, have limitations under high heat flux conditions. Therefore, our company has researched and developed a cooling system based on phase change materials (PCM) to achieve better thermal management.
What is Phase Change Cooling?
Phase change cooling technology (PCM) utilizes the characteristic of materials absorbing a large amount of latent heat during phase transition to manage battery heat effectively. Compared to traditional air and liquid cooling technologies, phase change cooling has the following advantages:
Simple Design, High Reliability
Phase change materials cooling does not require a complex fluid circulation system, reducing maintenance and failure risks.
Reasonable Temperature Regulation
Through the phase transition of the material, the battery system temperature can be reasonably adjusted, ensuring the battery operates within an appropriate temperature range.
Energy Efficiency
During the phase change process, the material absorbs heat, preventing the battery surface temperature from rising rapidly. Conversely, when the battery temperature drops below the phase change material’s threshold, the material releases heat, effectively preventing a rapid decline in battery surface temperature.
Liquid Cooling Technology: High Cooling Efficiency, But Costly and Challenging to Maintain
Liquid cooling technology uses high thermal conductivity fluids to contact the battery module for heat dissipation. Compared to air cooling, liquid cooling is more efficient but has drawbacks such as high weight, leading to lower overall energy density, system complexity, high cost, and challenging maintenance, limiting its widespread adoption.
Air Cooling Technology: Simple Structure, Limited Cooling Efficiency
Air cooling technology uses air to manage battery heat, offering a simple structure and low cost. However, its cooling efficiency is limited and cannot meet the thermal management needs of battery packs under high power and high-rate conditions. Additionally, air ducts occupy significant volume, reducing the overall energy density of the battery pack.
Our Research and Findings
Our R&D team has developed an innovative cooling system combining phase change materials and liquid cooling technology. This system leverages the high heat storage capacity of phase change materials and enhances cooling efficiency through liquid cooling. Experimental validation shows that our cooling system effectively controls battery temperature within an ideal range during the discharge process of lithium iron phosphate battery packs, significantly improving battery lifespan and safety.
We selected a paraffin-based composite phase change material (CPCM) with high latent heat and appropriate phase transition temperature as the cooling medium. In experiments, using pure paraffin as the battery thermal management (BTM) medium reduced the maximum battery temperature by 28.0% under 3C discharge conditions. Furthermore, by adding expanded graphite to the paraffin, we increased the CPCM’s thermal conductivity to 2.0 W/(m·K), further reducing the maximum battery temperature by an additional 5.42°C.
Numerical Simulation and Experimental Verification
To optimize the thermal management performance of battery packs, we used COMSOL Multiphysics software for numerical simulation and combined experiments to study the effects of different cell spacings and the amount of phase change material on the battery pack’s temperature field. We found that when the cells were evenly distributed with a 10mm spacing, temperature uniformity was optimal. Additionally, by optimizing cell arrangement and systematically reducing the spacing from the center to the edge of the battery pack, we could reduce the amount of phase change material by 12%, with the maximum temperature rise remaining unchanged, while the maximum temperature difference decreased by 34%.
Conclusion and Future Prospects
Through a series of studies and experiments, our company has successfully developed an efficient phase change cooling system for lithium battery packs. This system not only effectively controls battery temperature, improving performance and safety but also reduces material usage and costs. In the future, we will continue to explore and optimize phase change cooling systems, including developing new high-efficiency phase change materials, improving battery arrangement designs, and integrating intelligent thermal management systems.
We firmly believe that through continuous innovation and research, our company will contribute more to the future of sustainable energy and maintain a leading position in lithium battery thermal management technology.
