Battery Pack Thermal Management Safety: Choosing the Right Liquid Cooling Plate

In the realm of EVs, battery safety and performance are critically dependent on effective thermal management. Among the key components in battery thermal management systems, the cooling plate plays a central role. It regulates battery temperature by circulating coolant through internal flow channels, removing excess heat generated during charging and discharging cycles, or transferring heat to the battery in cold environments—ensuring optimal operating temperature at all times.
Battery cold plates are typically classified into two main types based on the cooling method: Liquid Cooling Systems and Direct Refrigerant Cooling Systems. Liquid cooling systems use a water-glycol mixture or similar coolant that circulates through internal channels in the cold plate to absorb and transfer heat away from the battery cells. This is the most widely used method in electric vehicles due to its reliability and maturity. In contrast, direct refrigerant cooling systems use refrigerant as the working fluid, flowing directly through the cold plate to remove heat. This approach eliminates the need for an intermediate coolant loop and can provide higher cooling efficiency and system simplicity, making it suitable for compact or high-performance applications. In this article, we will introduce liquid cooling plates in details.
 

1. Types of Liquid Cooling Plates

The market currently offers a variety of liquid cooling plate structures, each with distinct forming principles, advantages, and drawbacks. The most widely used types include stamped plates, extruded plates, and serpentine tube (harp tube) structures.

1.1 Stamped Cooling Plate

Stamped plates are manufactured by pressing aluminum alloy sheets to form the internal coolant flow channels. Thanks to the ductility and strength of aluminum alloy, this method supports the integration of cooling plates in CTP (cell-to-pack) and CTC (cell-to-chassis) designs. Stamped cooling plates allow for flexible flow path design, improving heat exchange efficiency and product stability.
--Pros: High design flexibility, good surface contact, efficient heat dissipation, excellent production scalability, and high pressure resistance.
--Cons: Higher cost, relatively strict surface flatness and assembly accuracy requirements.

1.2 Extruded Cooling Plate

Extruded plates are made by extruding aluminum profiles to create internal flow channels. They feature two flat surfaces that allow direct contact with battery cells, maximizing heat dissipation surface area.
--Pros: High production efficiency, robust structure, low cost, and high load-bearing capacity.
--Cons: Uneven wall thickness can impact pressure resistance; rigid structure may limit space utilization in compact designs.

1.3 Serpentine Tube (Harp Tube) Cooling Plate

This type uses aluminum tubes formed into flow channels and welded to manifolds on both ends. It’s commonly used in CMP (cell-module-pack) designs due to its simple structure, low weight, and low cost.
--Pros: Low cost, lightweight, simple structure, and easy to process.
--Cons: Single flow channel limits heat transfer efficiency; small contact area reduces cooling effectiveness; not ideal for high-density energy battery systems.

1.4 Comparison Table

Type	Principle	Advantages	Disadvantages
Serpentine	Tube formed by pressing and welded	Low cost, lightweight, simple structure	Limited flow, small contact area, average heat dissipation, weak load capacity
Stamped	Sheet stamping and welding	Flexible design, good contact surface, high efficiency, good pressure resistance	High cost, strict surface and assembly accuracy requirements
Extruded	Extrusion forming and precision sealing	High efficiency, low cost, robust structure	Complex sealing, surface flatness affects contact, not suitable for screw-based designs

 

2. Key Factors for Cooling Plate Selection

2.1 Thermal Performance

--Heat Dissipation Capability:
Flow path design significantly affects heat transfer. Stamped plates offer high flexibility, allowing increased heat flux and enhanced efficiency. Aluminum alloys with good thermal conductivity (150–250 W/m·K) are commonly used.
--Temperature Uniformity:
Uniform temperature is essential for battery consistency. Multichannel flow designs, especially in extruded plates, help minimize temperature gradients.

2.2 Mechanical Performance

--Strength and Pressure Resistance:
Cooling plates must withstand mechanical compression from battery cells and internal coolant pressure. While extruded plates offer robust structure, uneven wall thickness can reduce pressure tolerance. Stamped plates rely on brazing quality to ensure durability.
--Vibration and Impact Resistance:
Vibration testing under GB38031 can expose weaknesses. Harp tube plates may loosen at weld joints. Improperly designed stamped plates risk fatigue cracks. Extruded plates are generally strong, but poor joint cushioning can lead to damage.

2.3 Material Characteristics

--Thermal Conductivity:
Aluminum alloys strike a balance between weight, cost, processability, and thermal performance.
--Corrosion Resistance:
Prolonged coolant exposure can cause corrosion, thinning walls, or leaks. Surface treatments like anodizing enhance corrosion resistance, but extreme pH levels or harsh environments may degrade protective layers.

2.4 Cost Considerations

--Raw Material Costs:
Harp tube plates are the most cost-effective. Stamped plates have moderate costs, while extruded plates require high-quality profiles, increasing expenses.
--Manufacturing Costs:
Stamping and extrusion involve high initial tool and equipment costs. Advanced welding techniques like friction stir welding increase costs, while brazing is more economical. Complex channel designs also add to production costs.

2.5 Integration with Battery Packs

--Dimensional Compatibility:
Compact battery packs demand highly adaptable cooling plate designs. Harp tube plates suit smaller spaces, while stamped plates offer customizable flow paths. Extruded plates have larger contact areas but less spatial flexibility.
--Ease of Installation:
High integration and ease of assembly improve production efficiency. Designers must consider compatibility with the battery pack structure and assembly process.

Selecting the right liquid cooling plate involves balancing thermal performance, mechanical strength, corrosion resistance, cost, and integration requirements. While stamped plates dominate in next-generation CTP/CTC designs, extruded and harp tube types also hold value in specific scenarios. Understanding these factors helps engineers make informed choices to ensure the safety, reliability, and longevity of EV battery systems.