What is the reason for Tesla to replace the cheaper 18650 lithium-ion battery?

On February 19, 2017, a Tesla ModelX was involved in an accident on the 8 kilometers and 800 meters northbound of the Guangzhou Branch of Shenhai Expressway, and then it caught fire and exploded, pushing the Tesla in a suspicious direction. , Why do big factories like Tesla use such cheap 18650 batteries? Is it to save costs to deceive Chinese consumers?

At present, the emergence of batteries has indeed solved many problems, greatly improving various life efficiency, and the emergence of lithium-ion batteries has made people more aware of electricity. The more in-depth, 18650 lithium-ion battery is the longest used lithium-ion battery, and there is still a kind of lithium-ion battery, and the shadow of 18650 lithium-ion battery can be seen in many areas.

Why does Tesla use cheap 18650 lithium-ion batteries?

About Tesla’s 18650 battery. About 7,200 18650 batteries are placed in the base of the Tesla car, which supplies the car with super kinetic energy through series-parallel connection and Tesla's unique intelligent system. 7,200 batteries, are everyone scared by this data? Yes, why did Tesla dare to be the first and boldly use this small steel shell battery? Is it really deceiving Chinese consumers as the subject said?

Why does Tesla use cheap 18650 lithium-ion batteries?

Let’s take a look at Tesla. How did it start to produce electric cars? Almost poor and white, there is no battery production capacity of its own, enough battery life, cheap prices, and ready-made batteries on the market instead of getting into a deadlock due to battery procurement at the beginning, Tesla chose to use mature 18650 lithium ion battery. Cheap and large-capacity, easy to purchase, good consistency, relatively good security............ High-tech supplement that can't be made!

For this purpose, Tesla has developed a high-tech battery pack and has a very advanced BMS battery management system (BATTERYMANAGEMENTSYSTEM), which can be said to have been done under the premise of non-accident To a very high level of security. At the same time, in order to prevent accidents, Tesla has developed the Autopilot automatic driving system to allow vehicles to have better active safety. Regarding the difference between electric vehicles and ordinary diesel locomotives, industry debates often focus on the power performance of batteries and internal combustion engines, as well as the cost of batteries. The US financial website SeekingAlpha recently pointed out that the weight of the battery system itself is the key.

In terms of weight grade, the curb weight of the BMW 3 Series is roughly 3,400 pounds (about 1.54 tons), while the Tesla Model S is as high as 4,600 pounds (about 2.08 tons). ), of which the battery weighs 1,600 pounds, accounting for almost one-third of the weight of the vehicle. To this end, Tesla decided to develop new battery technology to reduce weight for the battery system, thereby reducing the weight of the new car.

At present, Tesla mainly uses 18650 cobalt-acid lithium-ion batteries supplied by Panasonic. The entire battery pack contains thousands of independent battery cells; the battery cost is about $250/ Kilowatt-hours can supply an energy density of 233 watt-hours/kg. In the future, Tesla plans to launch a new 20700 cobalt oxide lithium-ion battery. Although the battery is larger, it has improved the chemical composition (electrolyte and electrode) to increase the energy density.

Therefore, when the same power requirement is reached, the number of battery modules required is reduced, and the weight of the entire battery pack is reduced. According to Tesla's data, once the battery energy density reaches 333 Wh/kg, the weight of the Tesla Model 3 will be equivalent to that of the BMW 3 Series.

Because battery packs are far inferior in energy density to gasoline and diesel engines, major manufacturers are digging their heads to explore battery energy density and adopt overall lightweight methods for vehicles. For example, the BMW i3 can last 80 miles on a full charge, but the car weighs only 2,800-3,000 pounds (approximately 1.27-1.36 tons), which is largely due to the lightweight carbon fiber body.