German engineers disassembled the batteries of leading EV manufacturers to analyze performance.

Tesla and BYD dominate the global electric vehicle (EV) market, with Tesla leading in Europe and North America and BYD commanding the Chinese market. However, both manufacturers have disclosed little about their battery designs, leaving many details about their structure and performance unknown.

To bridge this gap, a team of researchers from three German universities disassembled battery cells from both manufacturers to analyze their design, composition, and efficiency.

Their findings, published this week in the journal Cell Reports Physical Science, reveal that Tesla’s batteries focus on high-energy density and performance, while BYD prioritizes volume efficiency and cost-effectiveness. The study suggests that BYD’s battery design allows for better thermal management, making it more efficient overall.

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The researchers examined Tesla’s 4680 cell and BYD’s Blade cell, assessing their mechanical structures, electrode materials, and electrical and thermal performances.

They also investigated manufacturing processes and material costs.

One surprising discovery was the absence of silicon in the anodes of both batteries—especially Tesla’s—despite silicon’s reputation for enhancing energy density. The team also found that the two battery types differed significantly in charge and discharge rates relative to their maximum capacities.

BYD’s Blade cell employs an innovative method to secure its electrode sheets by laminating the separator edges, which sit between the anode and cathode. Tesla’s 4680 cell, meanwhile, features a unique binder that sets it apart from conventional industry materials.

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Despite their differences, the two batteries share unexpected similarities. Both use laser welding instead of the more common ultrasonic welding to connect their thin electrode foils. Additionally, while BYD’s cell is much larger, the proportion of passive components—such as current collectors, housing, and busbars—is nearly identical to Tesla’s.

The research is part of Europe’s effort to reduce its dependency on Asian and American EV batteries as the automotive industry in Germany, Sweden, France, the United Kingdom and other European nations are moving towards an EV future. Further research will be carried out to assess how the design choices affect electrode performance and battery lifespan.

The study was conducted by the Production Engineering of E-Mobility Components at Aachen University, the Electrochemical Energy Technology Department of University of Muenster, and the Fraunhofer Institute for Ceramic Technologies and Systems in Dresden.

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