CCTV, Hefei, October 9th (Reporter Liu Jun) The reporter learned from the University of Science and Technology of China on the 9th that the research group of Professor Ji Xingxing and collaborators of the school has made a major breakthrough in the research of new lithium-ion battery electrode materials: a newly designed black Phosphorous composite materials make possible lithium-ion batteries with high capacity, fast charging, and long life. The results were published in the "Science" magazine on October 9th, Beijing time.

It is understood that electric vehicles are becoming more and more popular in the market, but the long charging time is also prohibitive. Traditional fuel vehicles can extend a range of 500 kilometers with full fuel in only five minutes, while advanced electric vehicles currently on the market need to "wait" for one hour to achieve the same range extension effect. The development of high-capacity lithium-ion batteries with fast charging capabilities has always been an important goal of the industry.

The electrode material is one of the key factors that determine the battery performance index. "We hope to find an electrode material that can not only give the industry expectations in terms of comprehensive performance indicators, but also adapt to the industrial battery production process." Professor Ji Hingxing said.

The author of the thesis, Dr. Hongchang Jin, introduced: “Energy enters and exits the battery through the chemical reaction between lithium ions and electrode materials. Therefore, the conductivity of the electrode material to lithium ions is the key to determining the charging speed; on the other hand, the electrode material per unit mass or volume contains lithium ions. The amount is also an important factor."

According to the introduction, black phosphorus is an allotrope of white phosphorus. Its special layered structure gives it strong ion conductivity and high theoretical capacity. It is an electrode material with great potential to meet the requirements of fast charging. However, black phosphorus is prone to structural damage starting from the edge of the layered structure, and the measured performance is far lower than theoretical expectations. Ji Hengxing's team adopted an "interface engineering" strategy to connect black phosphorus and graphite through phosphorus-carbon covalent bonds, which stabilized the material structure while improving the conductivity of the black phosphorus-graphite composite material to lithium ions.

But the electrode material will be enveloped by chemicals that gradually decompose in the electrolyte during the working process. Some substances will prevent lithium ions from entering the electrode material, just like dust on the glass surface hinders light penetration. The research team used a thin polymer gel to make a dust-proof coat and "wore" on the surface of the black phosphorous graphite composite material to allow lithium ions to enter smoothly.

"We use the conventional process route and technical parameters to make the black phosphorous composite material into the electrode sheet. Laboratory measurement results show that the electrode sheet can recover about 80% of the electricity after 9 minutes of charging, and it can still maintain 90% after 2000 cycles. The co-author, Xin Sen from the Institute of Chemistry of the Chinese Academy of Sciences said, “If mass production of this material can be achieved, matching cathode materials and other auxiliary materials can be found, and the cell structure, thermal management and Optimizing the design of lithium protection, etc., will hopefully obtain a lithium-ion battery with an energy density of 350 Wh/kg and a fast charging capability."

It is reported that a lithium-ion battery with an energy density of 350 watt-hours/kg can make the driving range of an electric car close to 1,000 kilometers, while the Tesla Model S has a driving range of 650 kilometers after being fully charged. The fast charging capability will increase the user experience of electric vehicles to a higher level.