Design and Performance of the BYD LFP/Graphite 4680 Cylindrical Cell

The increasing demand for large-format lithium-ion batteries in electric vehicles has accelerated the development of cell formats that offer higher energy density and improved pack-level efficiency. Among these, the 4680 cylindrical cell format, pioneered by Tesla, has gained widespread adoption due to its potential to simplify battery pack architecture while enhancing gravimetric energy density. Other cell manufacturers, including SamSung, Panasonic, BYD, and others, have adopted the 46XX format, incorporating various chemistries. This study presents a comprehensive analysis of BYD’s 4680 lFP/graphite cylindrical lithium-ion cells. Detailed physical teardown, X-ray imaging, electrochemical testing, and electron imaging were performed to evaluate both cell- and materials-level attributes. The teardown and X-ray imaging reveal an uncommon multi-tab configuration and homogeneously double-sided electrode coatings, with no silicon additives in the graphite anode. Electrochemical testing indicates energy densities of 374.6 Wh l −1 and 150.5 Wh kg −1 . Furthermore, hybrid pulse power characterization and electrochemical impedance spectroscopy show impressive rate capability, with low cell-level DC area-specific resistance (6–17 Ω·cm 2 across various SOCs) and an area-specific charge transfer resistance of approximately 5.9 Ω·cm 2 . These findings highlight a new direction for the 4680-cell format in both design and performance, establishing a strong foundation for future developments in large-format cylindrical battery technology.