Reporters learned from Tsinghua University on the 23rd that Liu Kai's research group of the Department of Chemical Engineering of Tsinghua University abandoned the traditional electrolyte design method and developed an electric field assisted supramolecular self-assembly layer technology. This technology seems to put a smart protective suit on and off the lithium battery, which is expected to solve the problem of "lying down" of electric vehicles in winter. The relevant research results were recently published in the international academic journal Energy and Environmental Science.

Lithium ion batteries are widely used in the market because of their long life, large specific capacity, no memory effect and other advantages. However, the problem of its performance degradation at low temperature has not been completely solved, leading to the frequent "freezing" shutdown of mobile phones in winter and "squatting" of electric vehicles.

Zhang Weili, the first author of the paper and a postdoctoral fellow in the Department of Chemical Engineering of Tsinghua University, introduced that when the battery needs to work, the "protective clothing" will automatically cover the surface of the lithium battery to form a dense protective film, which can not only prevent the electrolyte from decomposing under high voltage, but also accelerate the transmission of lithium ions, so that the battery can work efficiently at low temperatures. When the battery does not work, the "protective clothing" can be automatically taken off to restore the battery to its normal state. "Under the effect of 'protective clothing', lithium metal batteries can still discharge efficiently at - 79 ℃," he said.

In addition, this technology will greatly improve the performance of UAVs. Electric aircrafts such as UAVs put forward higher requirements for high specific energy, high power and safety of batteries, especially when flying in cold and low temperature environments, it is easy to have sudden voltage drop, insufficient flight power, and even crash. The "culprit" of these problems is electrolyte. The traditional electrolyte is easy to solidify at low temperature, making it difficult to "shuttle" between the electrodes, especially when lithium ions "jump" from the electrolyte to the electrode with great resistance.

"The electric field assisted supramolecular self-assembly layer technology can be used as a springboard to help accelerate the transfer of lithium ions from electrolyte to electrode by 'dressing' on the electrode surface, thus improving the endurance of lithium batteries at low temperatures. Experimental data show that this technology enables UAVs to fly efficiently at - 40 ℃." Liu Kai said, This technological breakthrough has injected new impetus into green travel and low altitude economic development in cold regions. In the future, with the further development of technology, low-temperature lithium batteries will be widely used in more fields, producing greater social and economic benefits.

(Reporter Jiang Jing)

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