Tesla vs BYD: Engineers rip apart rival EV batteries to unlock design secrets
Tesla prioritizes performance and energy density, while BYD focuses on volume efficiency and lower cost, the study found.
Engineers at the RWTH Aachen University in Germany took apart batteries from popular electric vehicle (EV) manufacturers Tesla and BYD to better understand their mechanical structure, characteristics, and how they work in general since very little information is available in the public domain.
Batteries are the most expensive component of an EV and the most critical one. A lot of anxiety related to adopting an EV stems from the battery – its range, charge retention capacity, charging times, and overall lifespan. Yet, prospective EV owners only get small bits of information about the battery, while much of the data about its capabilities and shortcomings remains undisclosed.
Jonas Gorsch, Research Associate Battery Engineering & Safety at RWTH Aachen University, who was involved in the work in an email to Interesting Engineering, explained:
Battery suppliers disclose only selective information to the public, as they want to prevent competitors from easily accessing specific design intricacies, such as contacting technologies or the particle topology of their active materials,
So, Gorsch and his team decided to tear apart batteries in the lab instead.
Why Tesla and BYD?
The researchers picked Tesla and BYD since they are the most popular EV brands in Europe/ North America and China respectively. Another important factor is that both EV brands are also involved in designing and producing the battery cells.
Gorsch in the email, added:
This gives them full control over the design and technology,
“This is evident in the unique design of these cells, which have clearly been developed with the overall system, battery pack, and vehicle integration in mind.”
In their research, Gorsch and his team focused on the Tesla 4680 cell and BYD’s Blade Cell. While taking apart each component, the researchers tried to determine the exact material composition of the cells while also studying their electrical and thermal performances and the processes used to assemble them.
What did they find?
The researchers were surprised to find that the anodes of the cells for both batteries did not contain any silicon, given that the material has been considered important in increasing energy density in batteries.
Another similarity between the batteries was how they used laser welding to connect thin electrode foils.
Gorsch to IE in the email, explained:
Laser welding, as a contacting technology, requires access from only one side of the product during production,
“This enables more flexible, space-efficient designs and simplifies the manufacturing process by reducing alignment constraints and improving scalability.”
Where the batteries differed is their approach of charging/ discharging rates when compared to their maximum capacity. Using the same C rate, the researchers analyzed the specific heating of both cells.
Gorsch in his email, noted:
If a 70 kWh pack were built using both cells and charged at 70 kW, the heating per cell volume of the BYD cell was approximately half that of the Tesla cell.
“This suggests that BYD cells enable easier thermal management at the pack level,”
Another way the batteries are different is that BYD deploys a different method of keeping electrode sheets in place by using an electrode stack that laminates the edges of the separator between the electrodes.
On the other hand, Tesla is unique in its approach, which uses a novel binder to hold together all the active materials of the electrodes.
Gorsch said in a press release,
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,
The current study did not cover the impact of mechanical cell design on electrode performances or the reasons for differences in the lifespans of the two battery packs. In the future, the research team also plans to analyze new battery cell designs as they are updated in newer vehicles.
The research findings were published in Cell Reports Physical Science.
READ the latest Batteries News shaping the battery market
Tesla vs BYD: Engineers rip apart rival EV batteries to unlock design secrets, source
