According to foreign media reports, a research and development team led by Professor Yang Quanhong of Tianjin University and Professor Lu Wei of Tsinghua University prepared a wax-PEO (plasma electrolytic oxidation) coating on the surface of lithium metal by a simple dip coating method It became an air-stable and waterproof lithium metal anode. As a commonly used inert sealing material, wax can be easily coated on the surface of lithium metal.
(Source: Chinese Science)
The lithium metal anode has the characteristics of high specific capacity, low potential and light weight, which can effectively improve the energy density of the battery. That is, the use of lithium metal anode will significantly improve the cruising range of electric vehicles and reduce the cost of batteries used for energy storage in the grid. . However, because lithium has high chemical activity, it is easy to cause dendrite growth and air instability, which leads to safety problems, so it is limited as an electrode material and is used in large-scale applications.
Lithium metal is very sensitive to moisture and oxidizing components in the air, which can cause insulating substances such as lithium hydroxide to form on its surface, which leads to deterioration of its electrochemical performance. In addition, when lithium is in contact with water, hydrogen and heat are generated, which may cause fire or explosion. The sensitivity of lithium metal puts forward higher requirements for the transportation, storage and processing of lithium metal anodes. Therefore, there is an urgent need to develop a lithium metal anode that is stable in air and waterproof, so that the lithium metal anode can be truly applied in the future.
In the field of electronic equipment, the use of packaging technology can protect electronic components from physical damage and corrosion of humid air and water, which also provides design ideas for how to protect lithium metal.
The wax-based composite coating developed by the researchers prevents lithium metal from adverse reactions in air and water. In batteries, such coatings slow the corrosion of the lithium metal anode surface by the electrolyte; the uniformly distributed PEO ensures that lithium ions can conduct electricity uniformly at the interface, inhibiting the growth of lithium dendrites.
Under the protection of wax-PEO coating, the lithium metal surface has not changed in the air with a relative humidity of 70% within 24 hours, and the high specific capacity retention rate is 85%. And even if it is in direct contact with water, there is no fire burning or capacity attenuation. After the coating is applied to the lithium metal anode, in a symmetric battery, stability is maintained for up to 500 hours, and the lithium-sulfur battery made of the lithium metal anode coated with the coating In 300 charge-discharge cycles, the capacity decay rate of the battery is as low as 0.075% after each cycle.
This study demonstrates an efficient packaging technology for air-stabilized and waterproof lithium metal anodes, which is easily scalable and suitable for other sensitive electrode materials.
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