Brief description of the new study on non-explosive lithium hydrated batteries

Researchers at the University of Maryland and the U.S. Army Research Laboratory have developed the first lithium-ion battery to use water and salt solution as an electrolyte and have a voltage of 4.0 volts for household appliances such as laptops, according to foreign media. At the same time, there is no fire and explosion risk existing in some commercial non-aqueous lithium batteries. Their findings were published in the American "Joule" magazine published on September 6.

"In the past, if you want high energy, you have to choose non-aqueous lithium batteries, but you need to compromise on safety," said Xukang, one of the authors of the research paper and an expert on electrochemistry and materials science at the US Army Research Laboratory. If you pay more attention to safety, you must accept low energy and use water batteries such as nickel-metal hydrogen batteries. Now, we have demonstrated that we can achieve both high energy and high security. "

The study is based on a study published in the 2015 issue of the American journal Science. The study developed a similar 3.0 Volt water electrolyte battery, but failed to achieve higher voltage due to the so-called "negative pole challenge." The negative pole challenge refers to a battery made of graphite or metallic lithium that is decomposed by a water electrolyte. In order to solve this problem and achieve a voltage span from 3 to 4 volts, Yangchongyin, assistant researcher at the University of Maryland and lead author of the research paper, designed a gel polymer electrolyte coating that can be applied to graphite or lithium positives.

The waterproof coating prevents water molecules from approaching the surface of the electrode and can decompose and form a stable interface when first charged -- a thin layer of decomposition that separates the solid positive electrode from the liquid electrolyte. With this interface, the battery can use the ideal cathode material, while also improving energy density and recycling ability.

"The key innovation here is to create the right gel that prevents water from touching the positive," said Wangchunsheng, a professor of chemistry and biomolecular engineering at the James Clark School of Engineering at the University of Maryland, who co-authored the study. "

The new battery with a gel coating improves safety compared to standard non-aqueous lithium batteries and improves energy density compared to other lithium water batteries. What is unique about this battery is that even if the interface layer is damaged(such as damage to the outer layer of the battery), its reaction with the positive electrode of lithium or lithium graphite is very slow, preventing the metal from directly touching the electrolyte and causing fire or explosion.

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