Brief Introduction of 4680 Cylindrical Cell(Ⅲ)

 

5. Cathode

Different electrodes are used in different products. LFP 4680 is used in low-range vehicles and energy storage batteries, focusing on providing more cycle times. Nickel-manganese 4680 batteries are used in medium-range vehicles and household batteries. High-nickel 4680 batteries are used in the Cybertruck and Semi.

Tesla’s cathode material focuses on high-nickel and cobalt-free direction but hasn’t proposed any innovations outside the mainstream path. They use the NCA single-crystal route to increase energy density by raising the voltage, with material thermal stability comparable to lithium iron phosphate.

5.1. NCA

The ternary cathode material routes are generally divided into two paths:NCA (Nickel Cobalt Aluminum), which Tesla adopts.NCM (Nickel Cobalt Manganese), such as NCM523, NCM622, NCM811 used by companies like CATL (Contemporary Amperex Technology Co. Ltd.).

The roles of elements in the cathode material are as follows:Nickel: Increases battery energy density and reduces battery costs. It is crucial for improving the range of the battery.Cobalt: Provides structural stability to the cathode, but it is expensive and environmentally polluting.Manganese, Aluminum: Improve material thermal conductivity, stability, and safety.Iron: An alternative to nickel, it has lower energy density but is cheaper and has higher charge-discharge cycles.Compared to NCM, NCA has a higher energy density and more stringent manufacturing requirements but has slightly lower safety. Tesla has increased the nickel content and reduced the cobalt content in their NCA formulation, thus increasing energy density and lowering costs.

The ternary cathode material routes are generally divided into two paths:NCA (Nickel Cobalt Aluminum), which Tesla adopts.NCM (Nickel Cobalt Manganese), such as NCM523, NCM622, NCM811 used by CATL: The roles of elements in the cathode material are as follows:Nickel: Increases battery energy density and reduces battery costs. It is crucial for improving the range of the battery.Cobalt: Provides structural stability to the cathode, but it is expensive and environmentally polluting.

Manganese, Aluminum: Improve material thermal conductivity, stability, and safety.Iron: An alternative to nickel, it has lower energy density but is cheaper and has higher charge-discharge cycles.Compared to NCM, NCA has a higher energy density and more stringent manufacturing requirements but has slightly lower safety. Tesla has increased the nickel content and reduced the cobalt content in their NCA formulation, thus increasing energy density and lowering costs.

5.2. Monocrystallization

Unlike increasing the nickel content to enhance energy density, monocrystallization aims to raise the energy density by increasing the voltage of the cathode material. Monocrystalline materials are more suitable for high voltage because they lack grain boundaries, which can improve the thermal stability and cycle performance of ternary batteries.Representative high-voltage monocrystalline material in the 5-series is the nickel 55 battery. It uses the same nickel content as NCM523 but achieves the energy density of NCM811, while also exhibiting more prominent thermal stability in the material aspect and lower cost compared to NCM811.

5.3. 4680 Battery Cathode Trends

The 4680 battery utilizes three different cathode materials: iron phosphate (LFP), nickel-manganese-aluminum (NMA), and high-nickel (NCA).

5.3.1. High-nickel direction dominates the 4680 battery currently

The high-nickel version is currently the main direction for Tesla’s 4680 battery. It is intended for use in high-range vehicles such as the Cybertruck and Semi. Additionally, the long-range and high-performance versions of Model 3 and Model Y can also use this high-nickel variant.

5.3.2. 4680 nickel-manganese version follows the high-nickel variant

After the technical maturity of the high-nickel version of the 4680 battery, Tesla will develop the nickel-manganese version, which will be used in medium-range vehicles like the Model Y and household batteries.

5.3.3. Potential use of iron phosphate cathode in the 4680 battery

There is a possibility of using iron phosphate as a cathode material in the 4680 battery. Tesla did not mention its cycle performance during the battery launch event because silicon-based anodes tend to expand, reducing the number of charge-discharge cycles. Once the nickel-manganese variant of the 4680 battery technology matures, the iron phosphate version 4680 is likely to be introduced. This variant would be used in low-cost vehicles and energy storage batteries, focusing on high cycle performance.

The development of 4680 batteries, from high-nickel variants to nickel-manganese variants, and eventually to iron phosphate variants, will drive the demand for related materials in the industry.

6.Industrialization Progress

6.1 Tesla was the first to announce the 4680 battery in 2020 and plans to reach 3 TWh of production capacity by 2030.

6.2 EVE and Panasonic are leading in the field of large cylindrical batteries.

6.3 Other battery companies such as LG, Samsung, CATL, BAK, and SVOLT have also made significant advancements.

7.Conclusion

The core innovative processes of the 4680 battery include: large battery cells + full tab design + dry electrode technology. These advancements have enhanced battery power and safety, improved production efficiency and fast charging performance, and reduced battery costs. This allows for further improvements in energy density and cycle performance. The current technical challenges lie in the production and welding of full tabs and the dry electrode process.