Copper Aluminum Bimetallic Gasket for Vibration-Resistant Low-Resistance Connections in EV Battery Packs

In electric vehicle battery packs operating under fast-charging high currents and rough-road vibration conditions, the dissimilar metal connection points between aluminum cell tabs and copper busbars endure sustained mechanical stress and thermal shock. Any slight increase in contact resistance can cause localized overheating when high current passes through, affecting battery pack safety and consistency. The copper aluminum bimetallic gasket, which replaces mechanical clamping with metallurgical bonding, aims to provide a vibration-resistant, low-resistance, lightweight transition connection solution for battery systems.

 

 

Low-Resistance Metallurgical Bonding: From Mechanical Contact to Atomic Bonding

Traditional connections between aluminum tabs and copper busbars in battery packs predominantly employ bolted clamping or ultrasonic welding. Bolted connections face stress relaxation risks under long-term vibration environments, with fretting wear on contact surfaces leading to oxide film thickening and progressively increasing resistance. Ultrasonic welding, while achieving localized connection, is significantly influenced by tab thickness and surface condition, with reliability verification over the full battery pack lifecycle still insufficient.

 

The copper aluminum bimetallic gasket achieves full metallurgical bonding between the copper and aluminum layers through the explosive welding process. High-velocity impact energy drives the copper and aluminum plates into oblique collision, with the interfacial metals undergoing plastic deformation and jetting under instantaneous high pressure, forming atomic-scale bonding. This process introduces no solder or intermediate layers, and the bonding interface exhibits a wavy interlocking morphology with increased bonding area and relatively low interfacial electrical resistance. During battery pack assembly, the copper side of the gasket contacts the copper busbar, and the aluminum side contacts the aluminum tab, with each side interfacing with the same metal, eliminating the galvanic corrosion risk of copper-aluminum dissimilar metal contact at its source. The dense metallurgical bonding interface can effectively block the penetration pathways of corrosive media, helping to maintain long-term connection resistance stability in the high-temperature, high-humidity battery compartment environment. Actual contact resistance and corrosion resistance performance vary depending on tightening torque, operating temperature, and vibration conditions.

Performance varies based on specific operating conditions. Actual results depend on installation conditions and operating parameters.

 

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Vibration Resistance and Lightweighting: Meeting Battery Pack Dynamic Operating Requirements

During vehicle operation, the battery pack is subjected to continuous vibration excitation from road bumps and body torsion, while the fast-charging process introduces significant temperature fluctuations. The thermal expansion coefficients of copper and aluminum are approximately 17×10⁻⁶/K and 23×10⁻⁶/K respectively, with temperature changes generating thermal stress at the connection interface. If the gasket material bonding strength is insufficient, the superimposed effects of long-term vibration and thermal cycling will accelerate interfacial microcrack propagation.

 

The metallurgical bonding interface of the copper aluminum bimetallic gasket can disperse and transfer the stress generated by thermal expansion differences and mechanical vibration across the larger area of the wavy interface during repeated vibration and thermal cycling, helping to suppress microcrack initiation and supporting long-term connection resistance stability. The low-density characteristic of the aluminum layer reduces the gasket deadweight compared to pure copper solutions, aligning with the lightweight design trend of battery packs. The copper-to-aluminum thickness ratio can be customized according to specific current-carrying capacity and tightening torque requirements. Actual vibration durability and electrical stability vary depending on vibration spectrum, temperature fluctuation range, tightening torque, and copper-to-aluminum thickness ratio.

 

 

Engineering Value for the EV Battery Pack Market

In the global electric vehicle market, the electrical connection reliability of battery packs is a critical factor affecting vehicle safety and range performance. The engineering value of the copper aluminum bimetallic gasket in this market lies in replacing mechanical contact with metallurgical bonding, helping to reduce the risk of resistance drift at dissimilar metal connection points under dynamic stress, and supporting battery systems in maintaining low-resistance, high-reliability electrical connections throughout the full lifecycle.

 

These copper aluminum bimetallic gasket products are manufactured using the explosive welding process, with the copper-to-aluminum thickness ratio customizable according to current-carrying capacity and installation space requirements. They are suitable for applications such as aluminum tab-to-copper busbar transition connections and inter-module busbar connections within battery packs. It is recommended that battery system engineers and EV manufacturers conduct field condition testing of copper aluminum bimetallic gaskets based on their battery pack current loading, vibration conditions, and thermal management design. By tracking indicators such as contact resistance variation trends, connection point temperature rise, and long-term durability performance, the technical compatibility and reliability assurance capability of the bimetallic gasket solution in specific battery system scenarios can be evaluated.

 

 

Important Note: The performance descriptions above are based on engineering experience under specific test conditions or internal test data. Differences may exist between laboratory results and actual operating conditions. Actual contact resistance, vibration durability, and working life vary depending on tightening torque, vibration spectrum, temperature fluctuation range, operating environment, and system design. This product is a conductive connection component for electric vehicle battery systems, and its suitability for specific applications must be verified by the user according to actual operating conditions and relevant industry standards.

 

 

 

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