The column presents a detailed comparison between two advanced lithium-ion battery cells used in electric vehicles: the BYD Blade prismatic cell and the Tesla 4680 cylindrical cell. Both are notable for their innovative designs and their significance in the electric vehicle battery market. The study focuses on understanding their design, materials, performance, and manufacturing processes through a teardown analysis.
The Tesla 4680 cell is a cylindrical battery with dimensions of 46 mm in diameter and 80 mm in height. It uses a high-nickel NMC811 cathode chemistry and is designed to deliver higher energy density and efficiency. This cell type was introduced in Tesla’s Model Y in 2022 and features a tabless design to improve manufacturing efficiency and energy transfer. The Tesla 4680 has a nominal capacity of 23.125 Ah and a nominal energy of 85.56 Wh. Its energy density is higher than the BYD Blade cell, at 241.01 Wh/kg gravimetrically and 643.3 Wh/l volumetrically.
The BYD Blade cell, on the other hand, is a prismatic cell measuring 965 mm in length, 90 mm in height, and 14 mm in thickness. It uses lithium iron phosphate (LFP) chemistry, known for safety, longevity, and lower costs. The Blade battery has a nominal capacity of 135 Ah and a nominal energy of 432 Wh. Its energy density is 160 Wh/kg gravimetrically and 355.263 Wh/l volumetrically. Despite lower energy density compared to Tesla’s 4680, BYD’s Blade cell offers better thermal efficiency and is easier to cool, which makes it more suitable for applications requiring high safety and durability.
One major difference lies in the manufacturing processes. Tesla uses laser welding technology for electrode connections, while BYD employs a combination of laser and ultrasonic welding. The Tesla 4680’s tabless design also streamlines manufacturing by reducing the complexity of connections inside the cell. BYD’s Blade cell uses a Z-fold electrode stack, which provides structural stability and ease of assembly in large-scale battery packs.
From an efficiency standpoint, the Tesla 4680 generates more heat during operation—around twice as much as the BYD Blade cell at the same C-rate. This requires more robust cooling systems in vehicles that use Tesla’s batteries. However, Tesla’s approach results in better energy density, making their batteries more suited for high-performance electric vehicles.
Both batteries use graphite anodes without silicon dioxide additives. The Tesla 4680 anode contains polyacrylic acid (PAA) and polyethylene oxide (PEO) binders. These materials contribute to the battery’s overall performance and longevity but may require further study to understand their long-term effects fully.
In terms of material costs, BYD’s LFP chemistry gives it a cost advantage. The study estimates that BYD Blade cells are cheaper by about €10 per kWh compared to Tesla’s NMC811-based cells, mainly due to the lower costs of iron phosphate and the absence of expensive metals like nickel and cobalt.
The study also includes an analysis of the thermal stability of the electrodes. BYD’s anodes and cathodes exhibit different thermal degradation behaviors compared to Tesla’s. For instance, the BYD anode uses carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR) as binders, which decompose at specific temperatures. Tesla’s anode, however, features PAA and PEO, with different thermal decomposition profiles.
The teardown analysis highlights the trade-offs between the two battery technologies. Tesla’s 4680 cell excels in energy density and performance, making it suitable for high-end electric vehicles that prioritize range and speed. BYD’s Blade cell, with its safer and cost-effective design, offers an excellent solution for mass-market electric vehicles focusing on safety and longevity. Both technologies represent important advances in lithium-ion battery design and will likely continue to evolve as manufacturers aim to improve energy storage solutions for electric vehicles.
