18650 lithium ion battery

　　Technology tracking behind Tesla’s 18650 lithium ion battery life of 1.6 million kilometers

　　Recently, Tesla disclosed a patent claiming that its 18650 lithium ion battery life has been extended to 1.6 million kilometers, attracting the attention of a large number of people in the power 18650 lithium ion battery industry.

　　It is understood that the patent was jointly developed by Tesla and Dalhousie University in Canada. By using new electrolyte additives, the service life of lithium batteries can be extended.

　　This new electrolyte additive is roughly MDO and PDO, and the prepared lithium 18650 lithium ion battery is an NMC/graphite bag 18650 lithium ion battery with high-temperature storage and long-term cycle performance.

　　The specific process is that MDO and PDO form an SEI layer on the surface of the graphite electrode, and the performance of the prepared 18650 lithium ion battery is better than that of the 18650 lithium ion battery containing VC.

　　At the same time, in long-term cycle tests, the performance of batteries prepared by 2% PDO/1% DTD and 2% PDO/1% LFO was also better than that of batteries containing VC.

　　The typical feature of the patent is that when the invented electrolyte additive (lithium salt) is combined with a non-aqueous solution, it can greatly improve the service life and performance of the 18650 lithium ion battery system.

　　Its 18650 lithium ion battery pack can maintain 95% of its life after 1,000 discharge cycles. Corresponding lithium batteries without additives have only a 25% lifespan. Then after 3,000 discharge cycles, the 18650 lithium ion battery using additives can maintain 90% of its life.

　　The earliest traceback was in August 2018, when Tesla submitted a patent titled "Dioxazolone and Nitrile Sulfite as Electrolyte Additives for Lithium-Ion Batteries".

　　Tesla also issued a statement saying: "Electrolyte additive methods are effective and can extend the service life and performance of lithium-ion batteries. In recent years, a large amount of research has developed such electrolyte additives, such as vinylene carbonate (VC) , fluoroethylene carbonate (FEC), allene-l-3-sultone (PES), ethylene sulfate (DTD) and lithium difluorophosphate (LFO), etc."

　　This shows that Tesla has deep scientific research and technical investment in the research of electrolyte additives.

　　To a certain extent, it also shows that although Tesla is a manufacturer of electric vehicles, it has a deep understanding of the performance development of power batteries.

　　Perhaps it is precisely because of this that Tesla can maximize the performance of the on-board 18650 lithium ion battery pack, allowing the Model S to travel 600 kilometers on a full charge, while the benchmark Porsche Taycan can only travel 320 kilometers.

　　In addition, from a technical perspective, Tesla's mass-produced vehicle with the best performance has a 18650 lithium ion battery life of about 800,000 kilometers. Now the patent has achieved 1.6 million kilometers, and the lifespan has been doubled. There must be a significant breakthrough in technology.

　　However, because Tesla did not indicate detailed test conditions such as charge and discharge rate, charge and discharge depth, and environmental severity when it announced the patent, the actual effect of the technology cannot be simply understood as a doubling from 800,000 kilometers to 1.6 million kilometers.

　　According to industry professionals, there are prerequisites for Tesla’s 18650 lithium ion battery to achieve a lifespan of 1.6 million kilometers.

　　For example, different charge and discharge rates and different charge and discharge states have great differences in 18650 lithium ion battery life.

　　Taking a step back, assuming Tesla's Model S is fully charged for 600 kilometers, the patented 18650 lithium ion battery can achieve approximately 2,700 deep full discharge cycles.

　　Corresponding to the technology of domestic power 18650 lithium ion battery companies, the first- and second-tier high-energy-density ternary batteries are about 1,000-1,500 times, and the third-tier ones are within 1,000.

　　If it is not fully discharged, according to Gaogong Lithium 18650 lithium ion battery, under the conditions of a 25°C environment, 0.33C charge/1C discharge, the charge and discharge depth is 50%, and the state of charge ranges from 30% to 80%. Domestic first- and second-tier batteries The company's 18650 lithium ion battery can cycle nearly 4,000 times.

　　Therefore, the key to Tesla’s patents attracting much attention is the consistency and other quality of its batteries, which are at least far ahead of the road to automotive standards.

　　For example, Tesla dares to claim that the 18650 lithium ion battery performance of its cars meets certain standards and is willing to sign a corresponding contract. Domestic companies generally do not dare to take this risk.

　　This is not to say that domestic 18650 lithium ion battery technology is lagging behind, but that in the production process, due to insufficient intelligent manufacturing, technology and standardization of equipment, the safety of single cells after leaving the factory cannot be achieved above the PPM level.

　　As a result, when facing the market, domestic companies dare not boldly guarantee or promise that their products can meet vehicle regulations. Coupled with corresponding legal constraints, they are even more afraid of damaging their market reputation and are very cautious.

　　All in all, Tesla's electrolyte patent brings at least two revelations.

　　First, the improvement of 18650 lithium ion battery performance can be achieved by seeking breakthroughs from the source.

　　For example, we attach great importance to the research and improvement of electrolytes, separators, and positive and negative electrode materials to achieve further improvements and breakthroughs in 18650 lithium ion battery performance.

　　Second, it is urgent to build a vehicle-level safety production system.

　　Domestic 18650 lithium ion battery companies must ensure that the quality errors of batteries after leaving the factory are extremely small and the degree of standardization is extremely high to meet the performance needs of end consumers. It is essential to pay attention to the production and manufacturing process and quality control.

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