Panasonic’s 4680 Prototype Battery for Tesla: A Game-Changer in Electric Vehicle Technology
Recently, Panasonic has announced its intention to collaborate with Tesla to develop new battery cells, including prototypes based on Tesla's 4680 cylindrical cell format. This partnership aims to leverage Panasonic's expertise in battery technology and production to support Tesla's ambitious goals for improving battery performance, reducing production costs, and accelerating the transition to sustainable transportation.
Introduction to Lithium-Ion Battery Designs
Lithium-ion batteries come in various sizes, and their shape is a crucial factor in optimizing their performance. One design that has shown significant potential for electric vehicle (EV) traction batteries is the cylindrical format. These batteries are large and efficient, reducing the effort and material required per kilowatt-hour (kWh) for the casing, terminals, and pressure safety devices. They also stack neatly, allowing many batteries to fit into the limited space inside a vehicle.
Tesla's Choice of Chemistry and Cell Designs
Despite the advantages of cylindrical batteries, Tesla chose to use a different chemistry for its batteries. In particular, Tesla uses a lithium-ion battery with a chemistry that, although slightly less stable, offers higher power density per liter. Additionally, Tesla opted to eliminate cobalt from its battery chemistry, as it was the most challenging material to secure. This shift involved using 18650 cells initially, which are common in laptops, torches, flashlights, and vape devices. These cells were readily available and could be sourced in large quantities. Tesla then developed innovative battery packs using these cells.
The Evolution of Battery Cell Sizes
To optimize battery performance, Tesla transitioned from 18650 cells to the 2170 format. This improvement involved designing cells that were both longer and wider, allowing for greater kWh per cell and a reduction in production costs since more energy could be packed into each cell wrapper.
The 4680 cell format represents a significant leap forward. With five times the volume of a 2170 cell, this new design addresses several key challenges in battery engineering. While not as voluminous as the prismatic cuboid cells used in some applications, the 4680 cells are not overly thick, allowing for effective cooling through a fluid akin to antifreeze. This cooling capability, combined with higher energy density, ensures that the battery pack can deliver more power without degradation, primarily caused by faster chemical reactions at higher temperatures.
Critical Improvements in Battery Design
One of the significant improvements in most cylindrical lithium-ion cells involves positive and negative electrodes being sheets of material, rolled into a cylindrical cell. However, this design introduces limitations in current capacity and additional manufacturing steps, particularly the joining of the tabs to the positive terminal.
Tesla has developed a revolutionary design where the tabs are integrated into the roll process, thereby enhancing current handling capacity and streamlining the manufacturing process. This innovation not only increases efficiency but also reduces production costs by simplifying the assembly process.
Conclusion
The partnership between Panasonic and Tesla in developing the 4680 prototype battery underscores the ongoing efforts to push the boundaries of electric vehicle technology. Through this collaboration, both companies aim to revolutionize battery performance, reduce production costs, and accelerate the transition to sustainable transportation. The potential of the 4680 battery is promising, offering a substantial improvement over current technologies in terms of energy density and cooling efficiency.