Tesla vs. BYD: Truth About Their Batteries

Electric vehicles (EV) are taking over the roads, but what really powers them? At the heart of it all are the batteries, and two companies - Tesla and BYD - leads the charge with their own unique approaches.

In a recent report published by Cell Report Physical Science, a group of engineers took apart Tesla’s 4680 cylindrical cell and BYD’s Blade prismatic cell to see what makes them tick. Their teardown gives us a rare look inside these cutting-edge power sources and reveals how different design choices shape performance, cost, and efficiency.

Tesla’s 4680 battery is built for high energy density and cost reduction. It uses a cylindrical shape and a tabless design, which helps improve energy flow and reduce resistance. On the other hand, BYD’s Blade battery takes a different route. It’s a prismatic lithium iron phosphate (LFP) cell designed for safety, longevity, and affordability.

These two batteries represent two different philosophies - Tesla prioritizes performance and efficiency, while BYD focuses on making batteries that are safer and cheaper to produce.

When the battery housing is cracked open, the difference becomes clearer. Tesla’s 4680 cell uses a jelly-roll configuration and relies on laser welding for its electrode connections. BYD’s Blade cell, meanwhile, has a long, flat structure with stacked electrodes and combines laser and ultrasonic welding for durability.

Performance-wise, Tesla’s 4680 cell is a powerhouse, packing an energy density of 241 Wh/kg and 643.3 Wh/L. That’s great for range and performance, but it comes with a downside - it generates three times more heat per volume than BYD’s Blade cell. That means Tesla’s design requires a more advanced cooling system to keep things running smoothly.

BYD’s Blade battery, while less energy-dense at 160 Wh/kg and 355 Wh/L, has a major advantage in safety and lifespan. Its LFP chemistry makes it more stable, meaning a lower risk of overheating or catching fire.

Materials also play a huge role in these differences. Tesla’s battery uses a high-energy nickel-manganese-cobalt (NMC811) cathode, while BYD sticks with LFP, which is more affordable and reliable.

Both use graphite anodes, but Tesla’s includes additional binders like polyacrylic acid (PAA) and polyethylene oxide (PEO), which could impact long-term durability while BYD uses carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) binders.

Cost is another big factor. Right now, BYD’s Blade battery is about €10/kWh (RM48/kWh) cheaper to produce than Tesla’s. That’s a major reason why LFP batteries are becoming more popular in lower-cost EVs.

This teardown makes one thing clear—Tesla and BYD have taken very different approaches to battery technology. Tesla’s 4680 cell is all about pushing the limits of energy storage and performance, but it needs a sophisticated cooling system to keep up. BYD’s Blade battery, while not as powerful, offers a safer, more affordable, and longer-lasting alternative.

As EVs continue to evolve, these insights will help shape the next generation of batteries. The future of electric mobility isn’t just about power - it’s about finding the right balance between cost, efficiency, and safety.