What is 4680 battery, what are the advantages and disadvantages of 4680 battery?
2023-10-16
The 4680 battery is cylindrical with a diameter of 46mm and a length of 80mm. The 4680 battery is different from the mainstream square battery.
The diameter of the 4680 battery is more than 2 times that of the 21700 battery installed in current models such as Tesla Model3, and the battery capacity is expanded to about 5 times. The interior also features a non-polar ear design that helps reduce internal resistance and heat, resulting in better energy consumption and charging performance for the vehicle.
The new battery pack has a moduleless design and consists of approximately 960 (40x24) cells, compared to the thousands of 21700 cells, because the energy density of the 4680 battery has increased by five times to 300Wh/kg.
what is the difference between 4680 battery and mainstream battery?
4680 battery in the anode material is also different from the mainstream battery, the mainstream is mainly graphite, 4680 battery uses silicon based anode, the material characteristics are high specific capacity, but there are easy silicon volume expansion, poor electrical conductivity, the first charge and discharge loss and other problems. In order to find a balance between energy density and stability, the current practice is to use a mixture of silicon and graphite.
In the process, PVDF coating is added to the positive and negative electrodes, more aluminum foil and copper foil are used to protect the electrode material, and the conductivity is more sensitive. And the non-pole ear design, the original positive and negative junction glue is reduced, reducing cost and increasing efficiency, and laser technology is used in welding.
What are the advantages and disadvantages of 4680 battery?
4680 Battery advantages:
1. improve mileage, improve energy density:
Positive and negative electrode material optimization to improve the energy density, the use of silicon carbon negative technology, graphite negative theoretical maximum battery capacity of 372Wh/kg, silicon negative theoretical maximum battery capacity of 4200Wh/kg. The energy density of the negative electrode can be increased by doping a certain amount of silicon material.Dry electrode technology is used for the first time to increase the battery energy density, wet electrode technology in the case of solvent, lithium and carbon mixed with lithium metal can not be well integrated with each other, there is the first cycle capacity loss problem, dry battery technology will greatly improve this problem, thereby increasing the battery energy density. At the same time, the positive electrode material thickness of the 4680 battery is increased from 55μm to 60μm, which further improves the active electrode material ratio, so that the energy density is increased by 5% while ensuring the power density.Packaging brings about an increase in the energy density of the system, the 4680 battery size increases, the number of individual batteries in the battery pack decreases correspondingly, the proportion of metal shell required decreases, and the proportion of materials such as positive and negative electrodes in the battery system increases, which can improve the energy density of the system.
2. Reduce costs:
Reduce the structural cost, the number of batteries in the battery pack is reduced, and the proportion of metal shells required is reduced, which can reduce the structural cost.
Reduced manufacturing costs, 4680 battery costs 17% less than 2170 cost. The dry electrode process is simple and eliminates the need for expensive coating machines because no solvent is used. In the preparation of the positive and negative electrode sheet, the active positive and negative particles are mixed with polytetrafluoroethylene (PTFE) to make it fibrosing into powder, and then rolled out into a film and pressed onto aluminum foil or copper foil, the preparation process completely jumps the step of adding solution, and the complicated coating, drying and other processes can be omitted, greatly simplifying the production process, and the production speed is also increased to seven times the previous, greatly improving the production efficiency.
3.conducive to the development of CTC chassis:
4680 adopts large-size battery housing, the mechanical strength of the battery is greater, and the unit battery with less number, greater strength and higher safety in the battery pack can be integrated with the chassis manufacturing, reducing later maintenance, and is more conducive to the chassis layout scheme in the vehicle design.
4. Improve security:
Cylindrical batteries are different from sheet batteries, and their heat dissipation is mostly axial, and the heat is dissipated from the pole ear. Traditional cylindrical batteries such as 2170 have only two pole ears, and the heat transmission channel is narrow, so the heat dissipation effect is not good.4680 battery pole ear area is greatly increased, the heat transmission channel is wide, greatly improve the heat dissipation effect (the heat output is only 20% of the traditional cylindrical battery), enhance the thermal stability of the battery.
5. Reduce the difficulty of thermal management:
The BMS(Battery Management) system can be simplified, with fewer individual cells in the battery pack, and it is easier to detect and balance the battery SOC(charge).
Reduce the difficulty of thermal management, smaller battery heat, fewer batteries, can reduce the heat dissipation power of the thermal management system, the use of a more streamlined system, reduce the difficulty of matching. It could also theoretically reduce the cost of thermal management systems.
6. Increase charging power:
The all-pole ear technology increases the output power: as the battery current path is wider and the internal resistance is greatly reduced the internal loss is reduced, and the battery power is greatly increased (the battery power is 6 times that of the 2170 battery).
4680 Battery disadvantages:
4680 battery has many advantages, but there are still the following difficulties in production, one is the difficulty of electrode welding technology, high yield control threshold. Second, the difficulty of dry electrode process has a threshold.
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