Evolution and mechanism of contact resistance of copper–aluminum electrical connectors in lithium-ion power batteries

Junlian Ge¹ , Jialin Zhu², Biao Ge¹ , Leon Sandforth³ , Junying Min⁴ *

¹School of Mechanical Engineering, Tongji University, Shanghai 201804, China.

²Hefei Gotion High-Tech Power Energy Co. Ltd., Hefei 230041, China.

³Chair for Electrical Energy Storage Systems, Institute for Photovoltaics (IPV), University of Stuttgart, Pfaffenwaldring 47, 70569 Stuttgart, Germany.

⁴College of Automotive and Energy Engineering, Tongji University, Shanghai 201804, China.

DOI:

https://doi.org/10.7494/cmms.2026.2.1041

Abstract:

This study investigates the sensitivity of factors influencing the contact resistance and reliability assessment of bolted copper–aluminum electrical connectors. Through continuous energized dynamic testing, the temporal evolution of the contact resistance and temperature of the contact area were monitored throughout the experiment. In conjunction with observations of contact surface morphology and microstructural composition analysis, the intrinsic mechanisms underlying anomalous changes in contact resistance were explored in depth. The results indicated that, during continuous current flow, the contact resistance of aluminum busbar assemblies without plating exhibited an “initially low → rapid increase → gradual stabilization” pattern, whereas nickel-plated aluminum assemblies maintained stable resistance. Quantitatively, the contact resistance of the nickel-plated group remained at approximately 15 μΩ, while that of the bare aluminum group rose to 400–750 μΩ. The evolution of the contact interface was asymmetric, with the dynamic growth of the oxide layer on the aluminum surface being the dominant mechanism increasing resistance. Moreover, the aluminum coating significantly reduced contact resistance and enhanced connection reliability.

Cite as:

Ge, J., Zhu, J., Ge, B., Sandforth, L., & Min, J. (2026). Evolution and mechanism of contact resistance of copper-aluminum electrical connectors in lithium-ion power batteries. Computer Methods in Materials Science, 26(2), – . https://doi.org/10.7494/cmms.2026.2.1041

Article (PDF):

Accepted Manuscript – final pdf version coming soon

Keywords:

Lithium-ion power batteries, Electrical connection, Contact resistance, Contact mechanism

Publication dates:

Received: 15.04.2026, accepted: 17.05.2026, published: XX.06.2026

Publication type:

Original scientific paper

References: