Brief description of high energy power battery

On January 7, Minggao Ouyang, an academician of the Chinese Academy of Sciences, said at the academic conference that China's 400 watt-hour/kg single-cell battery is expected to be industrialized in 2025. This timetable has caused hot debate in the industry. The energy of the battery 20700 high-performance lithium cobalt oxide battery is 333watt-hours/kg, which means that China is expected to change from “follow-up” to “leading” in the field of power batteries.

The scientific research project named by Minggao Ouyang has been supported by the national key research and development plan, and the full name is “Research on key technologies and related basic scientific issues of high-powered power batteries”. The research is based on the research team developed the high capacity of rich lithium manganese base of the anode materials, motor power battery energy storage is likely to be up to 400 watts per kilogram.

In recent years, with the support of national policies, China's new energy vehicles have been rapidly popularized, but the "stalks" that "do not dare to go to the suburban counties" have been difficult to straighten out. Breaking the single-stroke limit of 500 kilometers will greatly promote the promotion of electric vehicles. However, the vehicle load is limited. How to reserve as much energy as possible in a limited volume has become a key target for scientific research.

The project leader and professor of Peking University Dingguo Xia said: "To further improve the energy density of lithium-ion batteries, the specific capacity of cathode materials is the key." According to Dingguo Xia, for the specific capacity of cathode materials, the research team based on the preliminary work, deep understanding of the stability mechanism of lithium-rich materials and the generation mechanism of anion redox, optimize the performance of lithium-rich materials by regulating the anion redox mechanism.

In other words, the first question the team encountered was: What is the "about" of the anion redox capacity? Revealing this rule will lead the team to approach and find electrodes with good performance. The team also found that the geometry between atoms within the material affects the structure of the electrons, thereby affecting the ability of anion redox, studies the relationship between structure and efficiency, and hopes to improve the electrochemical properties of the electrode material through structural design.

"Improving the lithium content in the cathode material and allowing more anions to participate in the redox reaction is an important way." Xia Dingguo said that the development of high-capacity lithium-rich cathode materials has made it possible to further increase the energy density of power batteries. In addition to the preparation of a high-capacity lithium-rich cathode material and two high-capacity, high-stability lithium-rich materials—carbon composite materials, the project team also prepared high-capacity lithium battery anode materials.

In order to make the battery become a "muscle type man", in addition to obtaining reasonable positive and negative materials, it is necessary to design a feasible processing technology. For example, lithium-rich compounds need to be well dispersed in the electrode, maintaining a level of more than 60% in the system without condensing into a block. The more uniform the dispersion, the better the reversibility, and the better the charge and discharge efficiency.

At present, the battery needs further improvement. Dingguo Xia said that there are still two key issues that “dendritic lithium” restricts the progress of the new system battery and battery safety. Related experiments show that after 10 to 50 cycles of use, the voltage decays significantly and the electrodes do not work.

"Dendrite lithium" is a lithium-ion battery that is unique to liquid electrolytes. Lithium ions are reduced to crystallize into dendrites and grow continuously. To some extent, they may pierce the membrane. Scientists are currently seeking breakthroughs from two angles. One is coating and the other is studying solid electrolytes.

Dingguo Xia stressed that "the development of high-energy-density lithium-ion power batteries needs to be developed in the development of electrode materials, electrolytes and high-safety methods, and further advances in new analytical methods and battery preparation technologies."

In addition to increasing the energy density of lithium-ion batteries to 400watt-hours/kg, the project team will also focus on the research of new lithium-sulfur batteries and lithium-air batteries, whose energy density is expected to reach 500watt-hours/kg. Liquan Chen, an academician of the Chinese Academy of Engineering, said that lithium-air batteries are one of the development directions of power batteries. "The current development of hydrogen-oxygen fuel cells must use metal cans to ensure the safety of hydrogen use, while lithium-air batteries (negative electrodes are oxygen in the air). As long as mustard bag is enough. Lithium-air batteries should also be developed in terms of practicality and cost."

Starting from exploring the design method of improving the electrode and battery structure, establishing the battery polarization model and simulation technology, the journey of "slimming and fitness" of automobile power battery is still advancing.

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