The imitation mother-of-pearl layer diaphragm can improve the impact resistance of the lithium battery.

Recently, the research team of Yao Hongbin, Ni Yong and Professor Yu Shuhong of the University of Science and Technology of China, inspired by the high toughness of mother-of-pearl films, proposed a method to enhance the impact toughness of polyolefin films. The team effectively built a pearlescent coating on the surface of the polyethylene separator to effectively maintain the pore structure inside the separator after impact, thereby ensuring a uniform flow of lithium ions during battery charging and discharging. Compared with the flexible packaging battery using a commercial ceramic separator, the flexible packaging battery using the artificial pearl film shows a small open circuit voltage change, better cycle stability and high safety when subjected to an impact. The results of the study were published online on November 6 in'Advanced Materials' under the title Nacre Heuristic Separator Coating for Impact-Resistant Lithium Batteries. Currently, ceramic nanoparticle coatings are widely used to improve heat dissipation performance. The stability of the polyolefin separator and the wettability of the electrolyte. However, stress analysis shows that nanoparticle coatings are difficult to effectively resist the effects of local external shocks. During charging and discharging, it will inevitably lead to uneven flow of lithium ions in the battery, which will lead to lithium on the electrode. The deposition is uneven and even leads to the formation of lithium dendrites. Based on a deep understanding of the principle of high toughness of natural mother-of-pearl, the research team constructed an ordered structure of'brick and mud' imitating mother-of-pearl on the surface of the polyethylene film. When impacted by an external force, the mother-of-pearl coating effectively expands the force area, thereby eliminating the impact stress through the slip of the sheet, thereby effectively protecting the internal pore structure of the diaphragm and maintaining a uniform flow of lithium ions into the battery. Porous polyolefins are widely used as separators for commercial lithium-ion batteries due to their excellent electrochemical stability. The polyolefin separator serves as an anti-short-circuit insulating layer between the positive and negative electrodes of the battery, which greatly affects the safety performance of the battery. The internal porous structure facilitates the passage of lithium ions through the battery during charging and discharging, but at the same time it also leads to poor mechanical properties of the separator. Especially when the diaphragm is subject to a local external impact, its internal pore structure will inevitably cause deformation and cause rupture and partial pore closure, thereby affecting the performance and safety of the lithium battery. In order to further confirm the impact of the use of mother-of-pearl separators on the safety of commercial batteries, the research team perforated flexible packaging batteries equipped with two types of separators. Hit test. Compared with the flexible packaging battery using the commercially available nanoparticle-coated separator, the flexible packaging battery using the mother-of-pearl separator showed lower instantaneous open circuit voltage changes and faster voltage recovery (Figure 2a, b). The research team also continued to study the long-term performance of the flexible packaging battery after two impacts. The flexible packaging battery using the imitation mother-of-pearl coating isolation film still showed good stability in 80 cycles (Figure 2c). The above research results show that the mother-of-pearl separator has a good protective effect on the battery and can effectively reduce many hidden safety hazards. This work proposes a strategy for constructing a toughened diaphragm similar to pearl, and has proved its ability to improve the impact resistance of lithium batteries through theoretical simulations and experimental tests, which will open up new ways to improve the safety of lithium batteries. The lithium battery of the future. the way. The co-first authors of this article are Song Yonghui, a master student in the Department of Applied Chemistry, School of Chemistry and Materials Science, University of Science and Technology of China, and a doctoral student, Wu Kaijin, from the University of Science and Technology of China. Department of Modern Mechanics. The research was supported by the Ministry of Science and Technology, the National Natural Science Foundation of China, the Chinese Academy of Sciences and the National Synchrotron Radiation National Laboratory. Disclaimer: The articles published on this site are all from the Internet and do not represent the views of this site. If there is any infringement, please contact to delete WeChat: Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact delete A: my country's output of lithium batteries in 2019 is 15.72 billion, and the output of electric bicycles has soared! !