Why does Tesla insist on using cobalt lithium?

Tesla’s battery is one of the core components of electric vehicles. It was ridiculed and vilified in the early days. Even after the explosive parts were sold, many industry experts called it outdated battery technology with unclear goals. This is because Tesla is the only company that uses 18650 lithium-cobalt-ion batteries, which are traditionally used in notebook computers and are not as elegant as electric cars and pose safety risks. is that true?

According to the report, the impact of batteries on electric vehicles is obvious in terms of output power. Iron phosphate is currently the first choice in the market, such as Chevrolet Volt, Nissan Leaf, BYD E6 and FiskerKarma, because of their reliability, safety and charging times.

Tesla is the first car to use lithium cobalt ion batteries

Tesla’s sports cars and models are powered by 18650 lithium cobalt oxide batteries. Compared with lithium iron phosphate batteries, this battery has a more complicated process, high power, high energy density, and high consistency, but it has a low safety factor, poor thermoelectric characteristics, and relatively high cost.

According to industry insiders, the voltage is always lower than 2.7V or higher than 3.3V, and symptoms of overheating will appear. If the battery pack is large and the temperature gradient is not well controlled, there is a danger of fire. No wonder Tesla has been criticized for being unreliable in battery technology, because battery technology mainly focuses on voltage, current, and thermal control.

However, in practice, lithium-ion iron phosphate batteries are considered safer and more reliable, but they are not always available. In the preparation process, iron oxide can be reduced to elemental iron at high temperatures. Simple iron will cause a micro short circuit of the battery, which is contraindicated. In addition, in practice, the charging and discharging curves of lithium iron phosphate batteries are quite different, the consistency is poor, and the energy density is low, which directly affects the sensitive battery life of electric vehicles. According to a recent research report by Haitong International Securities, the energy density of Tesla batteries (170Wh/kg) is approximately twice that of BYD’s lithium-ion iron phosphate batteries.

Ms. Whittingham of Huntington University in the United Kingdom developed 18650 batteries for laptops, flashlights and other digital devices as early as the 1970s, but Tesla was the first company to use 18mm in diameter and 65mm in height in a car. Cylindrical lithium battery company.

Tesla’s director of battery technology, Kirt Kady, said in an earlier interview that Tesla also tested 300 different battery types in the market, including flat batteries and square batteries, but chose Panasonic’s 18650. On the one hand, 18650 has a higher energy density, is more stable and consistent. On the other hand, 18650 can be used to reduce the cost of battery systems. In addition, although the standard of each battery is very small, the energy of each battery can be controlled within a small range. Even if there is a defect in the battery pack, the impact of the defect can be reduced compared to using a large standard battery. In addition, China produces 18,650 batteries every year, and the safety level is improving.

Lithium battery NCR18650 is a high-capacity battery with a nominal voltage of 3.6V, a nominal minimum capacity of 2750 mA, and a component size of 45.5g. In addition, the energy density of the 18650 used in Tesla’s second-generation MODEL S is 30% higher than that of the previous sports car.

Tesla Chief Technology Officer JBStraubel said that since the Model S sports car was launched, battery costs have dropped by approximately 44% and will continue to fall. In 2010, Panasonic contributed $30 million to Tesla as a shareholder. In 2011, the two parties reached a strategic agreement to provide batteries for all Tesla vehicles in the next five years. Tesla currently estimates that the Panasonic 18650 will be installed in 80,000 models.

6831 lithium batteries were miraculously reconfigured

How does Tesla solve the 18650 safety risk? Its secret weapon lies in its battery processing system, which provides a solution to connect 68312 amp Panasonic 18650 packaged batteries in series and in parallel.

An electric car requires 18,650 batteries. The battery system of the Tesla Roadster contains 6,831 small battery cells, and the Model s has as many as 8,000 battery cells. How to place and assemble these large numbers of small batteries is particularly important.