Long battery lithium battery: "Future core" of new energy vehicles

Recently, media reported that the electric car manufacturer Fisker had just applied for a patent for a solid-state battery. The patent raised the EV's battery life to an astonishing 804 kilometers, and the charging time was reduced to one minute.

In China, as one of the core components for the development of electric vehicles, power batteries have always been the focus of research in the field of batteries. In the key special projects for new energy vehicles launched by the National Key Research and Development Program in 2016, the project “Long-term power lithium battery new materials and new system research” under the responsibility of the researcher of the Clean Energy Laboratory of the Institute of Physics of the Chinese Academy of Sciences aims to develop high-energy. Lithium batteries with high density and high safety to improve the cruising range of electric vehicles. The three lithium batteries, semi-solid lithium-sulfur batteries, and solid-state lithium-air batteries for long-term lithium-ion batteries proposed by the project will be the future of new energy vehicles in China. core.

Challenge battery limit energy density

"Improvement of the power battery cell energy density to 400 Wh/kg or more will help to significantly increase the mileage of the electric vehicle. Taking Beiqi EV200 as an example, a 400Wh/kg cell is equivalent to a volumetric energy density of over 800 Wh/L. There is a battery pack volume and 100 kilometer per ton power consumption, a charge can not only battery life 620 kilometers; also can reduce costs and prolong life, to solve the current big difference between the performance of electric vehicles and fuel vehicles." When interviewed by a reporter from Science and Technology Daily, he said.

As an important part of the national R&D of new energy vehicle power batteries, the task of this project is to develop new batteries with an energy density of 400 Wh/kg or more at the front end of the industrial chain, and to accumulate the key basic scientific issues of high-energy-density batteries. Technology, and provide an important reference and guidance for the simultaneous development of 300Wh/kg batteries.

The research and development team of “Long-term Power Lithium Battery New Materials and New System Research” is responsible for challenging the battery's limit energy density in this project.

Mass production cell energy density 300Wh/kg can be realized

The reporter discovered from the company’s public R&D program that the project team chose a high-nickel cathode and a nano-silicon carbon anode for the 300Wh/kg lithium-ion power battery route.

"From the recent progress, the technical indicators for mass production of battery core energy density up to 300Wh/kg can be achieved." Li Wei said.

In the recent research on new system batteries, the lithium-rich material used by the research team of “Longevity Power Lithium Battery New Materials and New System Research” has a positive electrode, and the silicon-carbon material has a negative electrode with an energy density of 348Wh/kg. Lithium-rich materials for the positive electrode, lithium metal as the negative electrode of the battery specific energy of 573Wh/kg; lithium sulfur battery specific energy of 600Wh/kg; primary lithium empty battery specific energy of 780Wh/kg.

"The development of high energy density batteries exceeding 300 Wh/kg, the negative electrode contains metallic lithium is an important common technology. Some research teams proposed the use of solid electrolytes or mixed solid electrolytes to solve the main problems faced by batteries using or containing lithium metal anodes. Technical challenge." Li Yu said.

In November 2013, the Chinese Academy of Sciences laid out a Class A project for strategic leadership of the Chinese Academy of Sciences. This project also supports the development of solid-state batteries. Three of the teams have made progress in polymer, sulfide, and in-situ solid state technologies.

Clear technical route but still face challenges

"The current development and production of liquid electrolyte lithium-ion battery soft pack batteries, the general liquid electrolyte weight percentage of 15% -25%, the negative electrode is carbon, silicon, etc. In the long run, the future needs to develop all solid state lithium metal batteries, negative Contains lithium metal, the battery does not contain any liquid." Li Yu said.

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

In addition, production environment control technologies such as drying rooms for large-scale production of lithium metal batteries have also been mastered. Despite the development of hybrid solid-state electrolyte batteries and all-solid-state lithium metal batteries, it also faces many scientific and technological challenges, including the cost control challenges.

"As long as a solid and in-depth study of the underlying scientific issues, and put forward feasible and creative comprehensive solutions, even if it is difficult, it is full of hope." Li Wei said. (Reporter Ma Aiping)