How to break through the development bottleneck of polymer lithium battery

　　Not long ago, media sources reported that electric car manufacturer Fisker had just applied for a solid-state battery patent, which increases the range of electric cars to a staggering 804 kilometers and shortens the charging time to one minute. .

　　In China, polymer lithium battery, as one of the core components for the development of electric vehicles, have always been a hot spot in the battery field. In the new energy vehicle special project of the National Key R&D Plan launched in 2016, Li Hong, a researcher at the Clean Energy Laboratory of the Institute of Physics of the Chinese Academy of Sciences, is responsible for the long-range power lithium battery new material and new system research project, aiming to develop high energy density, High-security lithium batteries are used to improve the cruising range of electric vehicles. The project proposes to study three long-lasting power lithium batteries: lithium-ion batteries, semi-solid lithium-sulfur batteries, and solid lithium-air batteries, which may become the future core of China's new energy vehicles.

　　Challenging the ultimate energy density of batteries

　　Increasing the energy density of power battery cells to more than 400Wh/kg will help significantly increase the driving range of electric vehicles. Taking the BAIC EV200 as an example, a 400Wh/kg battery cell is equivalent to a volumetric energy density of more than 800Wh/L. Keeping the existing battery pack volume and power consumption per ton per hundred kilometers unchanged, a single charge can not only last 620 kilometers; it can also reduce costs, extend service life, and solve the current large difference in performance between electric vehicles and fuel vehicles. Li Hong said in an interview with a reporter from Science and Technology Daily a few days ago.

　　As an important link in the overall layout of the national new energy vehicle power battery research and development, the mission of this project is to develop new batteries with an energy density of more than 400Wh/kg at the forefront of the industrial chain, and to accumulate understanding and key points of key basic scientific issues of high energy density batteries. technology, and provide important reference and guidance for enterprises to simultaneously develop 300Wh/kg batteries.

　　The long-range power lithium battery new material and new system research and development team is tasked with challenging the battery's ultimate energy density in this project.

　　Mass production battery cell energy density 300Wh/kg can be achieved

　　The reporter found from the public R&D plan declared by the company that for the 300Wh/kg lithium-ion power battery route, some project teams chose high-nickel positive electrodes and nano-silicon carbon negative electrodes.

　　Judging from recent progress, the technical indicator of mass-produced battery cell energy density reaching 300Wh/kg can be achieved. Li Hong said.

　　In the soft-packed cells of liquid electrolyte lithium-ion batteries currently developed and produced, the weight percentage of liquid electrolyte is generally 15% to 25%, and the negative electrode is carbon, silicon, etc. In the long term, there is a need to develop all-solid-state lithium metal batteries in the future, where the negative electrode contains metallic lithium and the battery does not contain any liquid. Li Hong said.

　　Although the technical route is relatively clear, it currently faces great challenges. Li Hong said that from the perspective of developing hybrid solid-liquid electrolyte batteries and all-solid metal lithium battery industries, it is necessary to focus on the development of solid electrolytes and metallic lithium materials to solve problems of interface ion and electron transmission, as well as volume deformation and thermal stability. Most manufacturing equipment can be realized by using existing manufacturing equipment from the lithium-ion battery and primary metal lithium battery industry.

　　In addition, production environment control technologies such as dry rooms for mass production of metal lithium batteries have also been mastered. Although the development of hybrid solid-liquid electrolyte batteries and all-solid-state metal lithium batteries still faces many scientific and technical challenges, including cost control challenges.

　　As long as we study the basic scientific issues in a solid and in-depth manner and propose feasible and creative comprehensive solutions, we will be full of hope even if there are many difficulties. Li Hong said.

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