(Editor/Shao Shuai) With the development of new energy vehicles, the upgrading and optimization of batteries will inevitably become the next hot spot for competition. Following the emergence of new terms such as blade batteries and cartridge batteries, the heat of the 4680 battery has also reached an unprecedented height. What is the magic of this battery product that has been well known to everyone?
What is 4680 Battery?
4680 battery, the full name is 4680 type electrodeless ear battery. As a new battery type released by Tesla, its energy has increased by 5 times, the mileage of the model product can be increased by 16%, and the power performance can be increased by 6 times.
In fact, it is an abbreviation for this battery, in short, a cylindrical battery with a battery diameter of 46mm and a battery height of 80mm. Before the 4680 battery 18650 battery and the 2170 battery, the same naming convention is also used. However, the last "0" of the 18650 battery represents the meaning of the cylinder, while on the 2170 and 4680 batteries, it is omitted.
So you see, the naming method of the scientific community is often so simple and crude.
Why use a 4680 battery?
There is no doubt that we seek a balance between energy and efficiency. The return of automotive products to the level of use is also focused on solving this problem. For batteries, when the energy density increases, the power density decreases. However, after research, it was found that the diameter of 46mm is a cylindrical battery, which not only has high energy density, but also takes into account high power density, which is one of the best choices for power batteries. Compared with the 18650 cylindrical battery, or the 2170 cylindrical battery, it still occupies a lot of advantages.
The first is the increase in the energy density of the battery pack. From a physical point of view, the basic characteristics of the 4680 battery increase the thickness of the cell, the curvature is reduced, and the hollow part is larger, which leads to an increase in the capacity of the internal active substance, further reducing the number of cells required in the battery pack. At the same time, the proportion of metal shells of 4680 batteries is small, while the proportion of positive/negative electrode materials is increased, further increasing the capacity of its single battery cell.
The second is the improvement of the safety of the battery pack. Battery heat dissipation issues involve a series of safety issues. For the 4680 battery, the omnipolar ear structure allows it to increase the channel of heat transmission, and further optimizes the heat dissipation problem of the battery, strengthens the thermal stability of the battery, and further improves the safety.
In addition, the mileage has increased significantly. Based on its own specifications, the 4680 battery is larger, more balanced in structure, and more intense, achieving the dual purpose of saving space and reducing weight. As a result, the relatively larger battery volume/capacity, combined with the lighter bodywork, makes the optimizations in terms of range obvious.
Finally, the power output is significantly improved. Due to the use of omnipolar ear technology, the current path of the 4680 battery is further expanded, the internal resistance component is reduced, the self-loss is reduced, and the battery output power is further improved.
Why does Tesla love the 4680 battery?
Speaking of which, we have to mention Tesla's CTC technology. For electric vehicles, increasing the energy density of the battery pack is undoubtedly a good choice to increase the endurance. Consumers in the market often take battery life as the criterion for judging. So, how to gather a larger sac energy density in a relatively constant body mechanism? The answer is: cut the complex and simplify.
Based on the first principle, Tesla's first reaction is to eliminate the "intermediate links", not only to remove the mold components, but also to delete the external box. This is the simplest and crudest explanation of CTC (Cell to Chassis) technology.
To meet such requirements, the 4680 battery is indispensable. Based on the requirements of CTC technology for battery structural strength, the structural strength of 4680 battery cells is higher, which has more advantages than 18650 and 2170 batteries. Simply put, the battery core, which originally required the protection of multiple layers of housing, is now directly protected by a layer of housing and the battery itself. The stainless steel housing of the 4680 is born to complete this task.
On the other hand, CTC technology is highly integrated, the cost of maintenance after a collision is higher, and the flexibility of the 4680 cylindrical battery after a violent collision or other cause of battery problems allows it to adapt to a variety of different environments.
Other advantages, full polar ear technology, CTC technology, high nickel + high silicon combination, will all appear in the model matching the 4680 battery. Such as diaphragm coating PVDF anti-silicon negative expansion, negative electrode addition of silicon nanotubes to improve conductivity, etc., will also be the secret weapon of the 4680 battery.
Does the 4680 battery have an opponent?
The answer is, yes.
One of the important manifestations of the battery is the contribution to the range of pure electric vehicles. Even the larger 4680 cylindrical battery will feel pressure in front of the CTP square battery.
Structurally, the 4680+ CTC technology can make the efficiency of the entire group reach more than 70%, while the CTP square battery can achieve an efficiency of 80%-90% in the range. After all, at the level of physical structure, the 4680 battery is still not large enough compared with the square battery.
But on the other hand, the single cell area of the square battery is too large, and a large number of surface contact methods make its heat dissipation problem more prominent, and it also brings great difficulty to thermal runaway protection. Therefore, the CTP square battery is not too suitable for the ternary battery direction, but more suitable for the lithium iron phosphate direction.
In the future, lithium iron phosphate batteries that focus on the economic and practical level, combined with CTP square batteries at the innate stability level, may be a good choice. The trend of the 4680 battery developing in the direction of ternary lithium and gradually filling high-end models is also obvious.
Write at the end:
In contrast, the 4680 battery has a greater energy density and better stability than the 18650 or 2170 battery. However, compared with the square battery, its objective factors in the volume of the battery can still not be ignored. Therefore, the 4680 battery is an optimization of the requirements of a specific environment, it is not exhaustive, but in the future to meet the needs of high-end pure electric models, or performance models, it is still the best choice.
(The picture comes from the Internet, if there is infringement, please inform and delete)