Hefei Research Institute: A series of important achievements in the research of lithium ion battery nanoelectrodes

Liujinhuai, a researcher at the Institute of Intelligent Machinery of the Hefei Institute of Physical Sciences of the Chinese Academy of Sciences, and Huangxing Liujinyun of the Jiu Group, etc., have made a series of achievements in the development of nanoelectrodes and their electrochemical performance in energy storage devices. The three-dimensional nanocomposite electrode with high volume was developed, and a new mechanism for attenuation of electrode capacity was proposed and demonstrated. The composite structure improves the electrochemical properties of lithium-ion batteries. The results of the research were published in international journals in related fields such as AvancedMaterials, ACSNano, and Small.

As an important energy storage device, lithium-ion batteries currently dominate in the rechargeable battery field due to their high energy conversion efficiency, low self-discharge rate, wide operating temperature range, and no memory effect. The research on the electrode and its electrochemical properties of lithium-ion battery has been an important field that all countries attach great importance to. With the development of electronic technology today, the demand for high-performance lithium-ion batteries(such as electric vehicles, drones, etc.) with high capacity, stable circulation, light weight, and small size is becoming more and more urgent. It is important to develop high capacity electrode(including mass capacity and volume capacity) and study its electrochemical characteristics in depth.

Nanoelectrodes are characterized by high activity, ion diffusion and short electron transmission paths. Starting from the most essential mechanism of capacity attenuation of nanometer electrodes, the researchers explored the root causes of capacity attenuation, and then specifically designed the high-capacity cyclic stable nanometer electrodes and developed the corresponding universal nanometer electrode preparation technology. For example, the Silicon / carbon three-dimensional nanotube array electrode designed to protect the inner and outer surfaces of the electrochemical active material Silicon(see Figure 1) can effectively reduce the effect of the solid electrolyte interface layer on electrochemical stability during the charge and discharge cycle. The dynamic changes of volume and structure of composite nanotubes during lithium/delithification were clearly observed by in-situ scanning electron microscopy(see Figure 2). A new principle of capacity attenuation caused by electrode nanostructure fatigue is proposed and demonstrated.

In addition, based on the universal three-dimensional nanostructure electrode preparation technology, a three-dimensional nanocomposite electrode without a frame structure was developed and its energy storage performance was studied(see Figure 3). After 200 cycles of charging and discharging, it was found that It still has a high full-electrode volume capacity(~ 1000 mAhcm-3), which is much larger than the current volume capacity of commercial graphite electrodes(~ 550 mAhcm-3), laying the foundation for the development of miniature batteries for wearable electronic equipment. The research results are based on the cooperation platform between the Hefei Institute of Science and the University of Illinois at Urbana-Champaign. With the development of the research, the development of high performance nanostructure electrode and its electrochemical characteristics in lithium-ion batteries are expected to make further breakthroughs.

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