New electrode materials “help” lithium-ion batteries “fast charge”

After charging for 9 minutes, about 80% of the power can be recovered, and 90% of the capacity can be maintained after 2000 cycles. Professor Ji Hengxing of the University of Science and Technology of China and his collaborators newly designed a new type of lithium ion battery electrode material-black phosphorus composite material , Making lithium-ion batteries with high capacity, fast charging capacity and long life possible. The results were published in Science on October 9.

As the awareness of environmental protection has taken root in the hearts of the people, electric vehicles have become more and more popular in the market, but the long charging time is prohibitive. Electrode material is one of the key factors that determine battery performance. “We hope to find an electrode material that can not only give industry expectations in terms of comprehensive performance indicators, but also adapt to industrial battery production processes.” Ji Hengxing said. Jin Hongchang, the first author of the paper and a member of the Jixingxing team, introduced that energy enters and exits the battery through the chemical reaction between lithium ions and electrode materials, so the conductivity of the electrode material to lithium ions is the key to determining the charging speed; electrode material per unit mass or volume The amount of lithium ions contained in it 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 an electrode material with great potential to meet the requirements of fast charging. The black phosphorus is prone to structural damage from the edge of the layered structure, and the measured performance is far lower than theoretical expectations. Ji Hengxing’s team adopted the strategy of “interface engineering” to connect black phosphorus and graphite through phosphorus-carbon covalent bonds to stabilize the structure and improve the lithium ion conductivity inside the material. The research team also made a dust-proof coating with a thin polymer gel and placed it on the surface of the composite material to allow lithium ions to enter. 　　

“We use conventional process routes and technical parameters to make black phosphorus composites into electrode sheets.” Xin Sen, the first author of the paper and a researcher at the Institute of Chemistry, Chinese Academy of Sciences, said that if mass production of this material can be achieved, a match can be found Cathode materials and other auxiliary materials, as well as optimization of battery structure, thermal management and lithium evolution protection, are expected to obtain lithium-ion batteries with an energy density of 350 watt-hours per kilogram and a fast charging capacity. 　　

The researchers said that they will continue to explore basic research and scale preparation on the basis of existing new technologies, and strive to make the research results closer to the actual needs of the battery industry.