Lithium cobalt oxide battery technology -Lithium - Ion Battery Equipment

Insufficient technical stability of lithium cobalt oxide battery -Lithium - Ion Battery Equipment

Following the fatal traffic accident of Uber's self-driving test vehicle due to the failure of the self-driving system, a TSLA Model X in California, USA, exploded after a traffic accident. The owner of the car died of his injuries after being taken to the hospital.

An industry insider told reporters that the good-looking data of TSLA performance and mileage can be said to be achieved under the premise of radical technology. He said that during the use of TSLA's 18650 batteries, as long as there is a slight inconsistency in the battery array, a circulating current will form inside the battery pack, causing self-discharge and greatly increasing the loss of the battery.

He also said that since the manufacturing process is not yet fully mature, the yield rate of 21700 cells of Panasonic and Samsung SDI will be lower than that of 18650 cells, while Model 3 has insufficient production due to battery module assembly problems, or it is related to this.(Lithium - Ion Battery Equipment)

TSLA again causes fatal accident

The TSLA in the accident first hit the barrier in the middle of the freeway, then the second lane on the far left, and after being hit by a Mazda in that lane, it ended up in the far left lane with an Audi. A total of three vehicles were involved in the collision. According to the local traffic police patrol, the Model X involved quickly caught fire before being struck by two other vehicles.

According to the reporter's understanding, the Model X was severely damaged after the incident, the front of the car was completely destroyed, and only the frame was burned. With so many of the car's batteries exposed after the accident, road crews were unable to immediately clear the wreckage from the road, and the CHP called in engineers from TSLA to evaluate the batteries.

According to the data, TSLA is currently the only car company that uses 18650 lithium cobalt oxide batteries. The above-mentioned battery is 18mm in diameter and 65mm in length, and is often used as a battery cell for notebook computers. Since lithium batteries are approaching the power threshold at this stage, TSLA has been using the method of placing thousands of batteries in a battery array on the bottom of the vehicle as its electric vehicle power. However, such a design increases the possibility of the battery array being hit when the vehicle collides, which in turn causes the cells or modules to be easily displaced, resulting in the disconnection and short-circuit of the wires used in parallel and series, resulting in a fire.

In addition, the 18650-type battery array of ModelS and ModelX also cancels the outermost insulating layer in order to reduce weight and cost. Although the company claims that it has excellent battery management system, battery grouping technology, and timely temperature monitoring system technology, the frequent accidents show that the natural defects of the 18650 battery array are still difficult to overcome.

In this regard, TSLA recommends that a large amount of water should be used to put out the fire after the battery catches fire, and that a thermal imaging camera should be used to monitor the battery condition within an hour after the battery is completely cooled.

The stability of lithium cobalt oxide batteries is questioned

In fact, as early as last April, a Model X caught fire and exploded after a collision in Guangzhou, causing serious damage to the vehicle. At that time, the owner questioned the quality of the TSLA Model X vehicle itself; at the beginning of this year, another TSLA spontaneously ignited because of the battery. So, why does the battery technology, which is the core competitiveness of TSLA, have repeated accidents?

Insiders told reporters that the good-looking data of TSLA performance and mileage can be said to be obtained under the premise of radical technology. He said that although the consistency of TSLA's 18650-type battery was stable in the early stage, in the process of use, the battery array must have inconsistent battery attenuation. Any slight inconsistency will create a circulating current inside the battery pack, causing self-discharge and greatly increasing battery losses.

When it comes to Model 3, he said that the current yield rate of 18650 cells of Panasonic and Samsung SDI is generally above 98%, but after switching to 21700 (battery array used by Model 3), the yield rate will be affected because the manufacturing process is not yet fully mature. The recently revealed Model 3 production is insufficient or related.

Previously, TSLA said an important production limiting factor for the Model 3 was battery module assembly. Musk said there were four "regions" in battery module production for the Model 3, and one of those "regions" had particularly serious problems. 



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