What does the Tesla 4680 battery mean?
Tesla 4680 battery refers to the battery with a diameter of 46 mm and a height of 80 mm, named after its size. The shape is cylindrical, different from the mainstream square battery. Tesla 4680 battery currently adopts the technical route of ternary lithium battery. It is not ruled out that lithium iron phosphate battery will be introduced later.
4680 belongs to ternary high nickel battery. The positive material is NCA (nickel cobalt aluminum). The common ratio of three metals of high nickel battery is 8:1.5:0.5. Nickel, cobalt and aluminum are three metal elements, so they are called "ternary lithium", which is generally divided into NCA and NCM (nickel, cobalt and manganese).
The 4680 battery is also different from the mainstream battery in terms of cathode material. The mainstream is graphite. The 4680 battery uses a silicon based cathode. This material has a high specific capacity, but there are problems such as silicon volume expansion, poor conductivity, and large initial charge discharge loss. In order to find a balance between energy density and stability, the current practice is to mix silicon and graphite.
In terms of technology, PVDF coating is added to the positive and negative electrodes of the 4680, and more aluminum and copper foils are used to protect the electrode materials, so the conductivity is more sensitive. The design of the electrodeless lug reduces the glue at the connection of the positive pole and negative pole, reduces the cost and increases efficiency. Laser technology is used for welding.
What are the advantages and disadvantages of the 4680 battery?
1. It is 5.4 times larger than the previous 2170 cylindrical battery, the battery capacity is increased by 5 times, and the vehicle endurance is increased by 16%. With the use of the endless lug design, the charging and discharging speed is increased by 6 times, which is expected to reduce the internal resistance of the battery to one fifth of the original, and the heat generation is lower and safer;
2. The 4680 is used in conjunction with the CTC scheme, that is, the battery cell is directly integrated into the chassis to improve the energy density of the battery system, reduce the weight of the vehicle, improve the production efficiency, and have more room for optimization in the ride;
3. The disadvantage is that it is impossible to determine whether the difficulty of heat dissipation inside the battery will increase, the battery cell will expand, and the battery life will be shortened.
