Lithium-ion battery applications are getting closer to the lives of ordinary people, but lithium resources on the planet are very limited and the cost of mining is high. The development of an alternative battery has become an important direction for scientists in various countries. In collaboration with Chinese and foreign teams, Professor Xia Hui of Nanjing University of Science and Technology has pioneered structural design and regulation methods, and has made important progress in the research of manganese-based cathode materials. Low-cost sodium-ion batteries are expected to replace lithium-ion batteries. Related results were published in the latest issue of Nature. · Newsletter.
Sodium is rich in resources, and the mining cost is only 1% of lithium. Therefore, the research and development of sodium ion batteries has become a field that scientific researchers scramble to "reclaim". The layered structure of sodium manganese cathode material has the advantages of high theoretical capacity, low price, and extensive sources, which makes it a popular research object for sodium ion battery cathode materials.
However, due to the narrow layer spacing of the sodium manganese cathode material, during the charge and discharge process, sodium ions with a larger radius will "squeeze" the structure of the cathode material when they migrate between the layers, which has become a key difficulty in restricting the development of sodium ion batteries. In addition to the layer spacing, another important factor affecting the performance of sodium ion batteries is the sodium ion content in the layered structure. Many researchers have tried various methods to prepare sodium manganese with different layered structures, but the performance indicators are difficult to meet the actual application requirements.
Professor Xia Hui's team pioneered the structural design and regulation method. In collaboration with the researcher Gu Lin from the Institute of Physics of the Chinese Academy of Sciences and Professor Meng Ying from the University of California, San Diego, based on the layered structure of birnessite, he successfully prepared both the interlayer and Layered nano positive electrode material with sodium ion content.
The specific capacity of the electrode made of this positive electrode material reaches 211.9 milliamp hours per gram, and the specific capacity of the lithium battery positive electrode materials currently on the market is about 140 milliamp hours per gram. During the charge and discharge process, the structure of this positive electrode material is stable and has no phase change, and the volume change is only 2%. After 1,000 cycles of charge and discharge, the specific capacity retention rate is as high as 94.6%, and the general specific capacity retention rate standard for the battery industry is about 80. %.