Taking cues from the characteristics of the electrolyte, researchers have made a significant breakthrough in the fast charging challenge of lithium-ion batteries. On February 29th, a team led by Professor Fan Xiulin from the School of Materials Science and Engineering at Zhejiang University, in collaboration with domestic and international researchers, published a paper in the prestigious journal Nature. The research team has developed a novel electrolyte that supports reversible charging and discharging of high-energy lithium-ion batteries over an ultra-wide temperature range from -70℃ to 60℃, while enabling rapid charging and discharging at room temperature.
Researching Lithium-ion pouch batteries. Image provided by the research team.
Lithium-ion batteries, known for their high energy density, long lifespan, lack of memory effect, and low self-discharge rate, are widely used in the field of new energy vehicles. However, it's undeniable that the charging speed, operating temperature, and safety of lithium-ion batteries still constrain further development in the new energy vehicle sector.
"To achieve fast charging in lithium batteries, it means that lithium ions need to migrate rapidly throughout the entire system. Currently, it is generally believed that the migration of lithium ions in the electrolyte and the electrolyte-electrode interface membrane is the speed-determining step of the entire process. The interface membrane is generated in situ with the properties closely related to the electrolyte," explained Fan Xiulin.
He further explained that the high ionic conductivity of the electrolyte requires the solvent to have high lithium ion solvation ability, but the generation of inorganic interface membrane requires the solvent to have low lithium ion solvation ability. Currently, it is impossible for the electrolyte to achieve both.
During the research process, the research team developed and verified a set of novel principles for extreme electrolyte design, breaking the traditional lithium ion transport mode, and identified the optimal formula for the new electrolyte from tens of thousands of solvents. Test data show that the ionic conductivity of this new electrolyte is four times that of commercial electrolytes at room temperature (25°C) and more than three orders of magnitude higher than commercial electrolytes at -70°C.
"Based on the new electrolyte, we have designed a 4.5-volt NMC811||graphite battery. At room temperature, it reaches 80% of its charge in just 10 minutes, demonstrating ultra-fast ion transport behavior," Fan Xiulin explained. While the cost of producing batteries with this new electrolyte is still relatively high, they can be used first in extreme temperature conditions such as polar expeditions, space exploration, and underwater exploration.
"At present, our team has collaborated with relevant companies. With technological iterations, we are confident in manufacturing new lithium-ion batteries and integrating them into new energy vehicles," said Fan Xiulin.
