New electrode material
About 80% of the power can be recovered after 9 minutes of charging, and 90% of the capacity can be maintained after 2000 cycles. The new lithium battery electrode material-black phosphorus composite material newly designed by Professor Ji Hengxing's research group of University of Science and Technology of China and his collaborators makes it possible for lithium batteries with high capacity, fast charging capability and long life. 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 the industry expectations in terms of comprehensive performance indicators, but also adapt to the industrial battery production process." Ji Hengxing said. Jin Hongchang, the first author of the paper and a member of Jixingxing’s team, introduced that energy enters and exits the battery through the chemical reaction between lithium ions and electrode materials. Therefore, the conductivity of electrode materials to lithium ions is the key to determining the charging speed; electrode materials per unit mass or volume contain lithium The number of ions is also an important factor.
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 Xingxing’s team adopted an “interface engineering” strategy to connect black phosphorus and graphite through phosphorus-carbon covalent bonds, which stabilized the structure and improved the conductivity of the material to lithium ions. The team also used a thin polymer gel to make a dust-proof coat to "wear" on the surface of the composite material so that lithium ions can enter smoothly.
"We use conventional process routes and technical parameters to make black phosphorus composites into electrode sheets." Xin Sen, co-first author of the paper and researcher at the Institute of Chemistry, Chinese Academy of Sciences, introduced that if mass production of this material can be achieved, Matching cathode materials and other auxiliary materials, and optimized design for cell structure, thermal management and lithium evolution protection, will be expected to obtain a lithium battery with an energy density of 350 watt-hours per kilogram and capable of fast charging.
The researchers said that on the basis of existing new technologies, they will continue to explore in basic research and scale preparation, and strive to make the research results closer to the actual needs of the battery industry.
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