The reporter learned on October 14 that the research group of Professor Ji Xingxing from the University of science and technology of China, in cooperation with UCLA and the Institute of chemistry, Chinese Academy of Sciences, has made a major breakthrough in the research of new electrode materials for lithium-ion batteries: the newly designed black phosphorus composite material makes it possible for lithium-ion batteries to have high capacity, fast charging and long life. The results were published in the journal Science.
Nowadays, electric vehicles are more and more popular in the market, but the long charging time is also prohibitive. Traditional fuel vehicles only need 5 minutes to reach full capacity, and the most advanced electric vehicles on the market need to sit and wait for one hour to achieve the same effect. The development of large capacity lithium-ion batteries with fast charging capacity has always been an important goal of the electric vehicle industry. The latest research breakthrough of the University of science and technology of China has brought mankind one step closer to this goal.
Dr. Jin Hongchang, the first author of the paper, introduced: in lithium-ion batteries, energy enters and leaves the battery through the chemical reaction between lithium ions and electrode materials, so the conductivity of electrode materials to lithium ions is the key to determine the charging speed; on the other hand, the amount of lithium ion contained in the electrode materials per unit mass or volume is also an important factor.
Black phosphorus is an allotrope of white phosphorus. Its special layered structure endows it with strong ionic conductivity and high theoretical capacity. It is a potential electrode material for fast charging. However, black phosphorus is prone to damage from the edge of the layered structure, and the measured performance is far below the theoretical expectation.
To this end, Ji Xingxing team adopted the interface engineering strategy to connect black phosphorus and graphite through phosphorus carbon covalent bonds, which not only stabilized the material structure, but also improved the internal lithium ion transmission capacity of black phosphorus graphite composite. During the working process, the electrode material will be wrapped by the chemical substances gradually decomposed by the electrolyte, and some substances will prevent lithium ion from entering the electrode material, just as the dust on the glass surface hinders the light penetration. The team used lightweight polymer gel as a dust-proof coat to wear on the surface of the black phosphorus graphite composite, enabling lithium ions to enter smoothly.
We use conventional process route and technical parameters to make black phosphorus composite into electrode pieces. The results of laboratory measurement show that about 80% of the power can be recovered after 9 minutes of charging, and 90% of the capacity can still be maintained after 2000 cycles If large-scale production of this material can be realized, matching cathode materials and other auxiliary materials can be found, and optimized design for cell structure, thermal management and lithium evolution protection, lithium-ion batteries with energy density of 350 Watt hours / kg and fast charging capacity will be obtained, said Xin Sen, co-author of the paper and researcher of Institute of chemistry, Chinese Academy of Sciences.
Such a lithium-ion battery can drive an electric car close to 1000 kilometers, compared with 650 kilometers when the Tesla models is fully charged. The rapid charging capability will bring the user experience of electric vehicles to a higher level.
Source: Qiao JunJing, editor in charge of science and Technology Daily_ NBJ11279