The 4680 cylindrical lithium battery refers to a battery with a diameter of 46 mm and a height of 80 mm, in a cylindrical shape, unlike the mainstream square batteries, and is named after its size. It is a battery manufactured by Tesla, designed to significantly increase driving range, reduce production costs, and be used in future products with high power consumption, such as Cybertruck pickups and semi-trucks.
I. Advantages of 4680 cylindrical lithium batteries
1. The 4680 cylindrical lithium battery 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 the charging and discharging speed by 6 times and 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 cylindrical lithium battery is used with the CTC solution, which means the battery cell is directly integrated into the chassis, improving the energy density of the battery system, reducing the weight of the vehicle, improving production efficiency, and providing more room for optimization in terms of passenger comfort;
II. Disadvantages of 4680 Cylindrical Lithium Batteries
1. The main drawback of 4680 lithium batteries is the uncertainty regarding whether they will lead to increased internal heat dissipation difficulties, cell expansion, and shortened battery life. While 4680 batteries offer many advantages, production still faces several challenges: firstly, the difficulty of tab welding technology and the high yield control required; and secondly, the complexity of the dry electrode process.
2. The 4680 cylindrical lithium battery has relatively harsh conditions on the positive and negative electrodes inside the cylinder. In addition, the heat dissipation inside the cell is more difficult, which has a certain impact on the battery life.
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 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.
