According to foreign media, researchers from the University of Maryland and the U.S. Army Research Laboratory have developed for the first time a lithium-ion battery that uses a salt solution as the electrolyte and has a voltage of 4.0 volts, which is the standard for household appliances such as notebook computers. Commercial non-aqueous lithium batteries have the risk of fire and explosion.

　　According to foreign media, researchers from the University of Maryland and the U.S. Army Research Laboratory have developed for the first time a lithium-ion battery that uses a salt solution as the electrolyte and has a voltage of 4.0 volts, which is the standard for household appliances such as notebook computers. Commercial non-aqueous lithium batteries have the risk of fire and explosion. Their research results were published in the American "Joule" magazine on September 6.

　　According to a report on the British Physical Science News website on September 6, one of the authors of the research paper and an expert in electrochemistry and materials science at the US Army Research Laboratory said: “In the past, if you wanted high energy, you had to choose non-water. Lithium batteries, but safety needs to be compromised. If you pay more attention to safety, you must accept low energy and use water-based batteries such as nickel-metal hydride batteries. Now, we have shown that we can obtain high energy and high safety at the same time."

　　This research is based on a study published in the US weekly magazine "Science" in 2015. That research developed a similar 3.0-volt water-electrolyte battery, but failed to achieve a higher voltage due to the so-called "negative electrode challenge." The negative electrode challenge refers to the fact that one electrode of a battery made of graphite or metallic lithium will be decomposed by the water electrolyte. In order to solve this problem and achieve a voltage leap from 3 volts to 4 volts, Yang Chongyin, the first author of the research paper and an assistant researcher at the University of Maryland, designed a gel polymer electrolyte coating that can be coated on graphite or lithium cathodes. .

　　This waterproof coating prevents water molecules from approaching the electrode surface, and can decompose and form a stable interface during the first charge-this thin layer of decomposition can separate the solid positive electrode from the liquid electrolyte. With this interface, the battery can use an ideal cathode material, while also improving energy density and cycle capacity.

　　One of the authors of the research paper, Wang Chunsheng, professor of chemical and biomolecular engineering at the James Clark School of Engineering at the University of Maryland, said: “The key innovation here is to create a suitable gel that can prevent water from contacting the positive electrode.”

　　The new battery with gel coating has improved safety compared with standard non-aqueous lithium batteries and improved energy density compared with other water-lithium batteries. The unique feature of this battery is that even if the interface layer is damaged (such as damage to the outer layer of the battery), it reacts very slowly with lithium or lithiated graphite positive electrode, which can prevent the metal from directly contacting the electrolyte and causing fire or explosion. .