According to foreign media reports, a research team from the Department of Engineering of The Chinese University of Hong Kong (CUHK) in China introduced a new type of electrolyte into the lithium ion battery in the water system, which has made important progress in improving high-energy batteries. This kind of electrolyte is usually used in skin creams. It is cheap, non-flammable, less toxic, environmentally friendly, and generates a stable voltage for daily use.
(Source: Chinese University of Hong Kong)
Electronic devices such as mobile phones, laptops, and even electric cars have improved our daily lives in many ways, and they all use lithium-ion batteries. Because lithium-ion batteries can be charged and can stably output energy, they have become the core of such products. Despite years of research, lithium-ion batteries still need to rely on toxic and flammable organic electrolytes to generate electricity. The serious safety hazards still have not been resolved. News such as Samsung smartphone explosions, Boeing aircraft battery fires, and electric vehicle battery fires continue Appeared, indicating that the safety of lithium-ion batteries has not been guaranteed.
Based on previous research on water-based lithium-ion batteries, the team introduced "molecular crowding" into a new type of water-based electrolyte, replacing the method of using lithium-ion salts as the main stabilizer.
"Molecular aggregation" is a common phenomenon in living cells. It describes that when large molecules (proteins, complex sugars, polysaccharides, etc.) or small hydrophilic molecules (metabolites, permeates) reach a certain concentration, the nature of solution molecules will take place. Sexual change. Due to the crowded environment, the activity of the water solvent will decrease due to changes in the hydrogen bond structure of the water.
The team chose to use poly(ethylene glycol) or PEG to replicate the "molecular aggregation" phenomenon in the electrolyte. PEG is a water-soluble polymer that can be easily combined with water-based batteries. It is also the basis for skin creams and personal lubricants. It can even be used as a defoamer in toothpaste and food and beverages.
Using this new stabilizer, a LiMn2O4 cathode and a Li4Ti5O12 anode, the team successfully expanded the stability window of the aqueous electrolyte to 3.2V and demonstrated that this new electrolyte can allow the battery energy density in more than 300 charge and discharge cycles Up to 75 to 100Wh/kg, and can work steadily; the use of gel coating can further increase the working voltage of the battery to above 4.0V, and the common side effects (hydrogen/oxygen evolution reaction) in water-based lithium-ion batteries are almost all eliminate. The researchers also conducted flammability tests to verify the fire resistance of the new electrolyte, which significantly improved the safety of lithium-ion batteries.
The researchers said: "This electrolyte can use many electrode materials that cannot be used with aqueous electrolytes. More importantly, this study found that it provides a new platform for designing aqueous electrolytes with larger voltage windows and higher stability, which can achieve safety. , Low-cost and environmentally friendly energy storage equipment." (Yu Qiuyun)
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