Core of Thermal Management for Heavy-Duty Truck Battery Packs: Dual Breakthroughs in Lightweight Materials and Manufacturing Processes

Heavy-duty trucks (HDTs), as the core force in road logistics, have made the safety, reliability, and cost-effectiveness of their battery systems a key technological focus. The battery tray, as the critical structural component that carries, protects, and manages battery modules, is now facing unprecedented extreme challenges.

Figure 1: Battery tray for electric heavy-duty trucks

1-Extreme Challenges for Heavy Duty EV Battery Tray

a. Stringent Mechanical Durability Requirements: Vibration, Impact, and Million-Kilometer Service Life

Heavy-duty trucks are designed with a service life of ≥1.5 million kilometers, 10 times longer than that of passenger vehicles. The battery tray must continuously withstand the following three types of extreme mechanical loads throughout its entire lifecycle:

·High-frequency random vibrations: When fully loaded and driving on unpaved, construction, or uneven roads, the chassis generates random vibrations across a wide frequency band (5 Hz–2 kHz). These vibrations not only test the fatigue limit of the tray's main frame but also induce microcracks in stress concentration zones such as welds, bolt holes, and flanges, becoming potential failure initiation points.

·High-g transient impact： Deep potholes, emergency braking, or handling drops can generate impact accelerations exceeding 50 g within milliseconds. The tray must instantaneously absorb/dissipate energy to prevent cell displacement, short circuits, or casing rupture.

·Cumulative fatigue damage: A million-kilometer service life means hundreds of millions of vibration cycles. Under alternating stress, aluminum alloys are prone to fatigue crack initiation and propagation, eventually leading to structural fracture. The core design task is to delay crack initiation until after the vehicle's retirement through topology optimization, local reinforcement, hybrid material integration, and process control.

b. Complex Thermal Management and Thermal Cycling Challenges

Due to their ultra-high capacity (hundreds of kWh) and high-power charging/discharging, heavy-duty truck battery packs generate massive heat. They also operate across arctic to tropical environments, facing extreme temperature differentials.

·Wide-temperature-range control: The tray and thermal management system (TMS) must precisely maintain cell temperatures within the optimal 25–40°C range under ambient temperatures ranging from -40°C to +85°C, with <5°C temperature variation between individual cells.

·High-stress thermal cycling: In accelerated aging tests, the system must endure thousands of -40°C ↔ +85°C thermal shock cycles (ramp rate: 5–15°C/min, dwell time: 5–15 minutes). This process causes repeated thermal expansion/contraction at material interfaces (aluminum alloy/sealant/plastic components), posing severe challenges to the reliability of welded/adhesive joints in integrated cooling channels.

2-Mainstream Material Solutions and Multi-Functional Integration Technologies

To address these challenges, the industry has developed a technology roadmap based on high-strength aluminum alloys, evolving toward highly integrated multi-functional designs.

a. Core Material Selection: The Dominance of 6xxx-Series Aluminum Alloys

In competition with steel, magnesium alloys, and composites, 6xxx-series (Al-Mg-Si) aluminum alloys have become the mainstream material for heavy-duty truck battery trays due to their excellent comprehensive performance, mature processing techniques, and high cost-effectiveness.

Key Alloy Grades and Properties:

·6061-T6: The most widely used grade, renowned for its outstanding strength, good weldability, and corrosion resistance.

·6005A-T6 and 6063-T6: Supplementary options, also offering good extrudability, suitable for components with slightly lower strength requirements.

b. Paradigm Shift in Design Philosophy: Thermal Management and Structural Health Monitoring

The design philosophy of modern heavy-duty truck battery trays has undergone a fundamental transformation—evolving from a purely mechanical "load-bearing structure" to a highly integrated "intelligent thermal regulation platform." This shift is primarily manifested in two key technological directions:

·Integrated Thermal Management (Mature Application)

Currently the most technologically mature and widely adopted approach, its core concept involves embedding cooling functionality directly into the tray's structural design to achieve compact and efficient thermal regulation.

·Structural Health Monitoring (SHM) Exploration (Early Stage)

This emerging technology aims to preemptively detect potential structural damage (e.g., cracks, deformations) during long-term service. However, it remains in the validation and laboratory research phase, lacking large-scale commercial deployment cases or sufficient long-term operational reliability data.

3-Analysis of Core Manufacturing Process Routes

The manufacturing processes for heavy-duty truck battery trays directly determine their cost, performance, and production efficiency. The mainstream approach combines aluminum extrusion and friction stir welding (FSW), optimally balancing performance requirements with small-to-medium batch production models.

a. Aluminum Extrusion

This process shapes aluminum billets into elongated structural components (e.g., crossbeams, longitudinal beams) via dies. As the cornerstone technology for battery trays, it offers:

·Advantages: Low mold costs, short development cycles, and adaptability to large, non-standardized parts in small batches.

·Limitations: Requires cutting, machining, and multi-step welding assembly, resulting in low automation, slower cycle times, and inferior efficiency compared to integrated die casting.

b. Friction Stir Welding (FSW)

A solid-state joining technology, FSW generates heat via a rotating tool to achieve high-strength aluminum welds, making it the premier choice for load-bearing/sealed joints:

·Performance: Weld strength reaches 80–90% of the base material, with no porosity/cracking defects. Minimal thermal distortion ensures IP67+ sealing and eco-friendliness.

·Constraint: Limited to flat/simple-curved weld geometries.

Aluminum alloy heavy-duty truck battery trays have transcended their role as high-strength lightweight structures to become multifunctional integrated platforms. However, proliferating functionalities introduce challenges like multi-physics coupling failures, process complexity, and reliability risks. Future breakthroughs will hinge on material-process-system co-innovation, leveraging adaptive interfaces and digital twin technologies to enable the safe and sustainable evolution of intelligent trays.

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