Continued: 4680 Battery-Battery Technology Upgrade-Cathode
5. Cathode
Different electrodes are used in different products. The iron-lithium version of 4680 will be used in low-endurance models and energy storage batteries, with more cycles; nickel-manganese-lithium 4680 batteries are used in medium-endurance models and household batteries; high Nickel 4680 batteries are used in cybertruck and Semi.
Tesla’s cathode material focuses on the direction of high nickel and cobalt-free, but it did not propose innovations other than the mainstream tech: using the NCA single crystal to increase the energy density by increasing the voltage, and the thermal stability of the material is comparable to that of lithium iron phosphate (Lifepo4).
The difference between NCM and NCA
5.1. NCA
Ternary cathode material routes are generally divided into two:
- NCA (nickel-cobalt-aluminum) adopted by Tesla
- NCM (nickel-cobalt-manganese), such as NCM523, NCM622, NCM811 by CATL
The role of elements in the cathode:
- Nickel: Improve battery energy density and reduce battery cost. It is the key to improving battery life.
- Cobalt: It has a strong structure as a positive electrode support, but it is expensive and pollutes the environment.
- Manganese and aluminum: improving the thermal conductivity of materials is the key to thermal stability and safety.
- Iron: An alternative to nickel, it has a low energy density, but it is inexpensive and has a higher charge and discharge frequency.
Compared with NCM, NCA has higher energy density and higher process requirements, but it is less safe. Tesla increases the content of nickel and reduces the content of cobalt, thereby increasing energy density and reducing costs.
……To be continued
