In battery module assemblies, interconnects serve as critical components that electrically join individual cells while managing thermal and mechanical interactions. Their design directly impacts performance, safety, and longevity by addressing three core challenges: minimizing electrical resistance, controlling thermal coupling between cells, and resisting mechanical vibrations.

Electrical resistance minimization begins with material selection. High-conductivity metals like copper and aluminum are standard, with copper preferred for its lower resistivity (1.68 × 10⁻⁸ Ω·m vs. 2.65 × 10⁻⁸ Ω·m for aluminum). However, aluminum’s lighter weight and cost advantages make it viable for applications where weight savings outweigh conductivity losses. Interconnect geometry also plays a role; thicker busbars reduce resistance but add mass, while laser-welded or ultrasonic-bonded joints avoid the resistance spikes seen in mechanical fasteners. Uneven contact pressure increases interfacial resistance, so precision in manufacturing is essential to maintain uniform connections.

Thermal coupling between cells is managed through interconnect design and thermal interfaces. Interconnects act as heat transfer paths, with their thermal conductivity influencing temperature gradients across the module. For example, aluminum’s thermal conductivity (237 W/m·K) helps distribute heat, but excessive conduction can propagate thermal runaway. To mitigate this, some designs incorporate thermal breaks or resistive coatings that limit heat flow while maintaining electrical connectivity. The interconnect’s surface area and placement also affect cooling efficiency; designs may integrate cooling channels or thermally conductive pads to balance cell temperatures.

Mechanical vibration resistance requires interconnects to withstand cyclic stresses without fatigue failure. In automotive applications, vibrations can exceed 20 Hz frequencies with displacements of several millimeters. Materials with high fatigue strength, such as copper alloys or plated aluminum, are selected to endure these conditions. The interconnect’s mechanical flexibility is tuned to absorb vibrations without transferring excessive strain to cell terminals, which could lead to cracking or loosening. Ribbon-style interconnects or braided conductors are sometimes used for their ability to flex without work hardening.

The interplay between these factors demands careful tradeoffs. A thicker interconnect may lower resistance but increase stiffness, exacerbating vibration-induced stresses. Similarly, a highly conductive thermal path might improve cooling but accelerate thermal runaway propagation. Computational modeling and physical testing are used to optimize designs for specific applications, ensuring interconnects meet electrical, thermal, and mechanical requirements simultaneously.

In summary, interconnects in battery modules are multifunctional elements that require balanced design approaches. Their performance hinges on material properties, geometric precision, and integration with thermal and mechanical systems. Advances in materials science and manufacturing techniques continue to refine their capabilities, enabling more efficient and reliable battery systems.