Successful development of ultrafast hydrogen negative ion conductors under mild conditions

2023-04-06

According to the Chinese Academy of Sciences, researcher Chen Ping and associate researcher Cao Hujun of the Chinese Academy of Sciences Dalian Institute of Chemical Physics (hereinafter referred to as "Dalian Institute of Chemical Physics") proposed a new material design and development strategy, which introduced a large number of defects and grain boundaries in the rare earth hydride LaHx lattice through mechanochemical methods, and developed the first ultrafast hydrogen anion conductor under mild conditions. The results were published in the international academic journal Nature on April 5th. In the study, researchers achieved ultrafast ion conduction under mild conditions (within the temperature range of -40 to 80 ℃), while previously reported hydrogen negative ion conductors could only achieve ultrafast conduction at around 300 ℃. Chen Ping said: "At - 40 ℃, the conductivity of the hydrogen anion conductor is as high as 102S/cm, and the activation energy is only 0.12eV. In addition, our team also realized the discharge of room temperature all solid state hydrogen anion battery for the first time, which confirmed the feasibility of this new secondary battery." Hydrogen anion is a potential hydrogen carrier and energy carrier with strong reducibility and high redox potential. Hydrogen negative ion conductors are materials with excellent hydrogen negative ion conductivity under certain conditions. They have broad application prospects in energy and electrochemical conversion devices such as hydrogen negative ion batteries, fuel cells, electrochemical conversion pools, membrane reactors, hydrogen sensors, and are expected to achieve a series of technological innovations in the future. However, this type of research faces problems such as limited material systems, high operating temperatures, and low ion conductivity under mild conditions. As early as the 20th century, researchers discovered that lanthanum hydride has rapid hydrogen migration ability, but its electronic conductivity is also high. In recent years, researchers have attempted to introduce oxygen into the lattice of lanthanum hydride to form oxygen hydrides to suppress its electronic conduction, but the introduction of oxygen also significantly impedes the conduction of hydrogen negative ions. In order to address these obstacles, the research team innovatively adopted mechanical ball milling preparation methods, which caused distortion of the lanthanum hydride lattice through impact and shear forces, disrupted the periodicity of the lattice, and formed a large number of nanocrystals and lattice defects. These lattice defects can significantly inhibit electron conduction, and their electronic conductivity decreases by more than 5 orders of magnitude compared to crystalline lanthanum hydride. It is particularly important that changes in material crystallinity do not significantly interfere with the conduction of hydrogen negative ions. They can "shock" electron transfer while still "maintain" the rapid transmission of hydrogen negative ions through a synergistic migration mechanism, ultimately achieving excellent hydrogen negative ion conduction characteristics. Many known hydride materials are ion electron hybrid conductors, "Chen Ping said

Edit:qihang    Responsible editor:xinglan

Source:GMW.cn

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