Tesla vs. BYD: A look inside their cutting-edge EV batteries

AACHEN, Germany — In the race to dominate the electric vehicle market, two companies stand above the rest: Tesla and China’s BYD. While Tesla pioneered the use of lithium-ion batteries and leads EV sales in North America and Europe, BYD began as a battery manufacturer before expanding into vehicles, surpassing Tesla in global EV sales in 2024. New research from multiple German universities gives us a look at the battery technology powering these automotive giants by directly comparing Tesla’s 4680 cylindrical cell with BYD’s Blade prismatic cell.

The research, published in Cell Reports Physical Science, reveals rare insights into the design, performance, and manufacturing processes of these cutting-edge batteries. By dismantling and analyzing both cell types, the researchers found major differences in energy density, thermal efficiency, and material composition that show the distinct design philosophies of each manufacturer.

“There is very limited in-depth data and analysis available on state-of-the-art batteries for automotive applications,” says lead study author Jonas Gorsch from RWTH Aachen University, in a statement.

For the average consumer, these differences translate into real-world impacts on driving range, charging speed, vehicle cost, and safety. The study offers a window into how battery technology, the heart of any electric vehicle, is evolving through different approaches to solve the same fundamental challenge: how to store more energy safely and efficiently while reducing costs.

The Tale of Two Battery Designs

Tesla’s 4680 cell (named for its 46mm diameter by 80mm height dimensions) represents the company’s latest innovation in battery design. It’s significantly larger than previous cells used in the Model 3, allowing for higher energy density and reduced production costs. The “tabless” design further cuts costs by eliminating the need for certain manufacturing steps.

BYD’s Blade cell takes a completely different approach, using a rectangular prism shape with dimensions of 965mm in length, 90mm in height, and 14mm in thickness. This long, thin design prioritizes safety and cost-effectiveness while offering surprisingly competitive performance metrics despite using different materials.

The most striking difference between the cells is their chemistry. Tesla opts for NMC811 (a nickel-manganese-cobalt blend with high nickel content), delivering impressive energy density of 241 Wh/kg and 643 Wh/l. In simpler terms, Tesla packs more energy into the same weight and volume. BYD uses LFP (lithium iron phosphate), which achieves a more modest 160 Wh/kg and 355 Wh/l. This choice reflects BYD’s focus on cost-effectiveness and longevity over maximum range.

When examining heat management, the researchers found that the Tesla 4680 cell generates twice the heat per volume compared to the BYD Blade cell at the same charging rate. This difference impacts the cooling systems needed for fast charging and has implications for battery longevity and safety. Overall, the study revealed that BYD’s battery is more efficient because it allows easier temperature management.

Looking Inside: Construction and Materials

When researchers took apart the batteries, they found some major differences in how Tesla and BYD build their cells. Inside BYD’s Blade battery, the key components, the positive and negative layers (cathodes and anodes), are stacked in a Z-folded pattern with many thin layers in between. This design makes the battery safer and more durable, but it also means that electricity has to travel a longer path through the battery, which can reduce efficiency. To keep everything securely in place, BYD uses a special lamination method, sealing the edges of the separator (the thin layer that prevents short circuits between the positive and negative sides).

Tesla takes a different approach with its 4680 battery, using a “jelly roll” design, sort of like rolling up a long strip of paper. This setup helps electricity flow more directly, improving performance. One noticeable feature is a small empty space in the center, which likely helps with manufacturing and connecting the battery’s internal parts.

Unlike many other battery manufacturers that use ultrasonic welding, both Tesla and BYD rely on laser welding to connect their thin electrode foils. Despite the BYD cell being significantly larger than Tesla’s, both batteries have a similar proportion of non-active components, such as current collectors, housing, and busbars.

“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,” says Gorsch.

Cost vs. Performance: The Bottom Line

Material cost analysis revealed that despite the BYD Blade cell requiring more assembly steps, it achieves a cost advantage of approximately €10 (~$10.85) per kWh due to using less expensive materials instead of the nickel and cobalt found in Tesla’s NMC811 cathode. At current price levels, this represents a significant cost advantage for BYD in the highly competitive EV market.

For electric vehicle buyers, these design differences translate to meaningful real-world trade-offs. Tesla’s higher energy density allows for longer driving ranges in the same battery volume, while BYD’s more thermally efficient design enables faster charging with less sophisticated cooling systems. The lower cost of BYD’s LFP chemistry makes their vehicles more affordable, while the higher performance of Tesla’s NMC811 chemistry appeals to the premium segment of the market.

Researchers say this study’s results provide valuable research and an industry benchmark for similar designs, especially for battery-cell developers when deciding on format, size, and active materials. Further studies are needed to determine the impact of mechanical cell-design choices on electrode performances in EV batteries, as well as the lifespans of the Tesla and BYD cells.

This battery battle between Tesla and BYD offers a fascinating glimpse into the invisible engineering that powers our transportation future. The question remains: which approach will win in the long run: Tesla’s high-performance strategy or BYD’s cost-efficient design? When deciding between cost, range, or performance, there is no perfect solution. Perhaps the real victory lies not in one design dominating the other, but in how this competition is speeding up the entire industry’s shift toward electric vehicles.