The Tesla 4680 battery refers to a battery with a diameter of 46 mm and a height of 80 mm, named after its size. It has a cylindrical shape, unlike the mainstream square batteries. The Tesla 4680 battery currently uses ternary lithium battery technology, but the possibility of releasing a lithium iron phosphate battery version in the future cannot be ruled out.
The 4680 is a ternary high-nickel battery. The positive electrode material used is NCA (nickel-cobalt-aluminum). The common ratio of nickel, cobalt, and aluminum in high-nickel batteries is 8:1.5:0.5. Nickel, cobalt, and aluminum are three metallic elements, hence the name "ternary lithium". Ternary lithium batteries are generally divided into NCA and NCM (nickel-cobalt-manganese).
The 4680 battery differs from mainstream batteries in its anode material. While mainstream batteries primarily use graphite, the 4680 battery uses a silicon-based anode. Silicon boasts high specific capacity but suffers from drawbacks such as easy volume expansion, poor conductivity, and significant initial charge/discharge losses. To find a balance between energy density and stability, the current approach is to use a mixture of silicon and graphite.
In terms of manufacturing process, the 4680 battery features a PVDF coating on both the positive and negative electrodes, and uses more aluminum and copper foil to protect the electrode materials, resulting in more sensitive conductivity. The tabless design eliminates the need for adhesive at the original positive and negative electrode connections, reducing costs and increasing efficiency. Laser technology is used for welding.
Advantages and disadvantages of 4680 batteries
1. It is 5.4 times larger than the previous 2170 cylindrical battery, with a 5-fold increase in battery capacity and a 16% increase in vehicle range. It adopts a tabless design, which increases charging and discharging speed by 6 times. It is expected to reduce the internal resistance of the battery to one-fifth of the original, resulting in lower heat generation and greater safety.
2. The 4680 is used with the CTC solution, which means the battery cells are directly integrated into the chassis, improving the energy density of the battery system, reducing the weight of the whole vehicle, improving production efficiency, and providing more room for optimization in terms of ride comfort;
3. The downside is that it is impossible to determine whether there will be problems such as increased difficulty in heat dissipation inside the battery, cell expansion, and shortened battery life.
