Electric vehicles (EVs) are reshaping the global automotive landscape, with Tesla and BYD leading the charge. Tesla has previously dominated the EV market in Europe and North America, while BYD holds the top position in China. Despite their prominence, both manufacturers have been tight-lipped about the details of their battery technology—until now.
A new study published in Cell Reports Physical Science offers a rare glimpse into the inner workings of these high-tech power sources.
Tesla, founded in 2003 by a group of engineers, including Elon Musk, has revolutionized the EV industry with its sleek, high-performance vehicles and cutting-edge battery technology. The company’s focus on innovation, long-range capabilities, and a robust Supercharger network has made it a leader in North America and Europe. Tesla’s 4680 battery cell, introduced in 2020, was designed to improve energy density, reduce manufacturing costs, and extend vehicle range.
BYD (Build Your Dreams), a Chinese automaker and battery manufacturer, was established in 1995. It began as a battery supplier before transitioning into the EV market, where it has become a dominant player. Unlike Tesla, BYD focuses on producing affordable, practical EVs with an emphasis on efficiency and safety. Its Blade battery, launched in 2020, is designed to be space-efficient, cost-effective, and thermally stable, addressing safety concerns related to traditional lithium-ion batteries.
A look Inside EV Batteries
To uncover the engineering secrets behind these batteries, researchers from RWTH Aachen University dismantled and analyzed Tesla’s 4680 cells and BYD’s Blade cells. Their goal was to compare each battery’s mechanical structure, material composition, and performance.
“There is very limited in-depth data and analysis available on state-of-the-art batteries for automotive applications,” Jonas Gorsch, lead author of the study and researcher at RWTH Aachen University in Germany, said in a recent statement.
Their findings highlight key differences in design philosophy. Tesla’s battery prioritizes high-energy density and performance, making it ideal for long-range EVs. On the other hand, BYD’s battery focuses on volume efficiency and lower-cost materials, making it more economical and easier to manage thermally.
One of the most surprising discoveries was the absence of silicon in the anodes of both battery types.
“We were surprised to find no silicon content in the anodes of either cell, especially in Tesla’s cell, as silicon is widely regarded in research as a key material for increasing energy density,” Gorsch noted.
Unexpected EV Similarities
The study also uncovered differences in how each battery charges and discharges. Tesla’s 4680 cell utilizes a unique binder to hold together the active materials in its electrodes. In contrast, BYD’s Blade cell employs a novel processing step to laminate the edges of the separator between the anode and cathode. These design choices influence battery performance, lifespan, and manufacturing costs.
Despite their differences, Tesla and BYD batteries share some surprising similarities. Both use laser welding instead of standard ultrasonic welding to connect their thin electrode foils. Additionally, although the BYD Blade cell is physically much larger than Tesla’s 4680 cells, the proportion of passive components—such as current collectors, housing, and busbars—remains similar in both designs.
Better EV Design?
The insights from this study could have significant implications for the future of EV battery design.
“The findings provide both research and industry with a benchmark for large-format cell designs, serving as a baseline for further cell analysis and optimization,” Gorsch said.
Understanding the trade-offs between energy density, efficiency, and cost can help battery developers refine their designs and improve the next generation of EV batteries. Further research is needed to determine how these design choices impact the lifespan and long-term performance of the Tesla and BYD cells.
For now, Gorsch and his colleagues’ recent study provides a crucial look at two fundamentally different approaches to powering future electric vehicles.
Kenna Hughes-Castleberry is the Science Communicator at JILA (a world-leading physics research institute) and a science writer at The Debrief. Follow and connect with her on BlueSky or contact her via email at kenna@thedebrief.org