Lithium-ion batteries with no risk of explosion may become practical

Chinese American scientists say they have developed a new type of lithium-ion battery based on a hydro-based electrolyte, which not only eliminates the risk of explosion in traditional lithium-ion batteries, but also achieves energy density at the level of traditional lithium-ion batteries, a big step toward the practical application of safe lithium-ion batteries.

This work was carried out by Professor Wangchunsheng of the University of Maryland, Dr. Yangzhongyin, and Xukang, a senior chemist at the US Army Research Laboratory. The paper was published in the Joule magazine of American Cell Press.

"This is the first four-volt battery to achieve a water-based electrolyte. In principle, it is a major fundamental breakthrough. "Yangzhongyin and others said in an e-mail to reporters. They explained that the use of highly flammable organic electrolytes in conventional commercial lithium-ion batteries is a serious safety hazard. The problem with replacing organic electrolytes with non-flammable water-based electrolytes is that the electrochemical stabilization window of the former is generally less than 2 volts. Once the electrode voltage exceeds this number, the electrolyte loses stability and therefore the energy density is limited.

The key to the new study, they explain, is to avoid direct contact of lithium metal or graphite electrodes with water molecules in a water-based electrolyte, leading to hydrogen reduction. To this end, they developed a very hydrophobic colloidal protective material, evenly coated on the surface of the electrode, effectively preventing the failure of the electrode caused by the water decomposition side reaction.

More importantly, they found that in the initial charge and discharge cycle, certain components of the protective layer formed in situ a more dense and hydrophobic solid electrolyte interface layer on the negative electrode surface, further passivation of the negative electrode surface. And this solid interface layer can repair itself under the condition of partial damage, which ensures the long-term stability of the battery.

Wangchunsheng and Xukang pointed out that the research results provide new directions and ideas for the development of a safe water-based lithium ion battery in Gaodianya's window. In the basic scientific sense, "stable 4-volt water electrolytes can bring many new opportunities to various electrochemical devices." At the same time, hydro-based lithium ion batteries can eliminate the necessary safety devices in traditional lithium ion batteries, further reducing the weight of battery components.

They stressed that the current study is only a concept verification in the laboratory and that there is still a long way to go before commercialization. In the next step, they plan to further optimize and improve the chemical composition and battery structure of the electrolyte protection layer, and increase the battery cycle life from the current 70 to 100 cycles to the commercial standard of more than 500 cycles.

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