Samsung SDI Fast Charge Lithium Battery Graphite Material Technology Latest Development

by:CTECHi     2021-08-21

  The country’s strong subsidy policy for new energy vehicles has greatly stimulated the development of the new energy vehicle industry. Up to now, the state’s fiscal subsidies for new energy vehicles have reached 50 billion yuan. Although the fraud scandal broke out, the country still spares no effort. Supporting the development of the new energy automobile industry, with many positive stimuli, lithium-ion battery manufacturers have deployed power batteries. As a huge lithium-ion battery supplier, Samsung SDI is naturally not far behind. Recently, many news pointed out that Samsung SDI is actively preparing to enter the market. Power battery industry.

The biggest difference between    power battery and ordinary lithium-ion battery is its extreme requirements for fast charging and safety. Compared with traditional fuel vehicles, the biggest disadvantage of electric vehicles is the charging time. The charging time of electric vehicles is often as long as ten hours, which severely limits the convenience of electric vehicles. Therefore, it is urgent to carry out traditional graphite anode materials. Transformation to improve the fast charging capability of lithium-ion batteries.

   In order to improve the rapid charging ability of graphite materials, it is necessary to shorten the diffusion path of lithium ions. At present, there are two main methods commonly used-preparation of ultra-fine powder graphite materials and porous carbon materials. Greatly shorten the diffusion path of Li+ and improve the rate performance of graphite materials. However, due to the increase in surface area, the irreversible capacity loss of the material will also increase. Therefore, the research focus on fast charging carbon materials is 'how to reduce the irreversible capacity of the material' loss'.

   The current common method for preparing porous carbon materials is high temperature oxidation or chemical oxidation, which produces a large number of micropores on the surface of graphite to promote the diffusion of lithium ions, which can significantly improve the rapid charging ability of lithium ion batteries , But these methods are currently difficult to overcome the problem of high irreversible capacity.

   Recently, Jae-Hyun Shim of Samsung SDI and others have developed a graphite surface modification method that uses KOH corrosion to modify the surface of graphite materials. High temperature calcination is not required, which not only improves the rapid charging of graphite materials, but also avoids the high irreversible capacity loss of the materials. The artificial graphite material used by Samsung SDI is provided by Shanshan Technology. The graphite material is first mixed with 20wt% KOH solution and stirred at 80°C for 24h, then filtered and cleaned, and dried in vacuum at 80°C for 12h. Modified artificial graphite can be obtained.

  The electrochemical test shows that the graphite material treated with KOH at room temperature has better rate performance than the untreated graphite material. At a charge rate of 2.5C, the capacity retention rate reaches 100 cycles. 96.7%, while the capacity retention rate of untreated graphite material is only about 50%. The test results of charging rate from 0.1C to 6C show that the rate performance of the graphite material after KOH corrosion treatment is significantly better than that of the untreated graphite material. The improvement, especially when the charging rate is higher than 2C, has obvious advantages.

   The rapid charging ability of the graphite material corroded by KOH is mainly due to the large number of nano-pores on the surface. At the same time, the crystalline structure of the graphite surface is destroyed due to the corrosion of KOH. High-resolution TEM can find that a large number of tunnels are generated on the surface of graphite, which can greatly shorten the diffusion path of Li+ and increase the charging rate of the material.

  Samsung SDI’s research on fast-charging graphite materials shows its ambition to enter the power battery industry. It is worthy of the high vigilance of domestic power battery manufacturers. If the national level of protection is withdrawn, it will face powerful foreign countries. Manufacturers are we confident that we will have the last laugh? Domestic manufacturers must increase investment in technology research and development, and only technology is the capital that dominates the field of power batteries.

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