Work

Experimental characterization of thermal contact resistances for laser-welded battery cell connections using laser flash analysis

Year: 2026

Type: article

Abstract: Reliable thermal management and system design are essential for the safety and performance of lithium-ion batteries, particularly under high-load and fast-charging conditions or in the case of thermal runaway. While extensive research has been conducted on optimizing electrical contact resistance and mechanical stability of battery cell connections, the thermal contact resistance (TCR) at cell-to-busbar interfaces is still unexplored. This study presents the first experimental characterization of the TCR for laser-welded battery cell connections using laser flash analysis. Four typical material combinations of aluminum (Al), copper (Cu), and Hilumin (Hi), i.e., Al–Hi, Al–Al, Al–Cu, Cu–Al, laser-welded with varying process parameters, were investigated in a temperature range from 0 °C to 240 °C. The TCR results ranged from approximately 1 × 1 0 − 5 m 2 K W −1 to 4 × 1 0 − 5 m 2 K W −1 , which is substantially lower than previously reported for pressed joints. Al–Hi joints showed a pronounced reversible temperature dependence of the TCR and an irreversible TCR increase after thermal cycling due to the growth of intermetallic compounds. The TCRs of the Al–Al, Al–Cu, and Cu–Al joints remained more stable. Electrical contact resistances were also measured, but no consistent correlation with the TCR based on the Wiedemann–Franz law could be established, highlighting the need for direct thermal characterization. • Characterization of TCRs for laser-welded battery cell-to-busbar connections with LFA. • Measurement of TCRs for Al–Hi, Al–Al, Al–Cu, and Cu–Al joints from 0 °C to 240 °C. • Significantly lower TCRs for laser-welded joints than reported for pressed joints. • Reversible and irreversible TCR increases in Al–Hi joints due to intermetallics. • Inapplicability of the Wiedemann–Franz law to predict TCR from electrical resistance.

Source: Journal of Energy Storage

DOI: 10.1016/j.est.2026.120559

Authors: Stefan Schaeffler, Michael K. Kick, Franz Roehrer, Michael F. Zaeh, Andreas Jossen

Institution: Technical University of Munich

Language: English

Topic: Advanced Battery Technologies Research

Subfield: Automotive Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Affordable and clean energy

Open Access status: hybrid

Estimated APC paid: $3,560