Recently, Professor Li Li's team from NEU has made significant progress in the field of metal negative electrodes for lithium metal batteries. The study titled A Crystalline Carbon Nitride-based Separator for High-performance Lithium Metal Batteries was published in the world-class journal Proceedings of the National Academy of Sciences of the United State of America (PNAS) (DOI: 10.1073/pnas.2302375120). NEU is the first author unit, and doctoral student Di Shuanlong from the College of Sciences and doctoral student Li Hongguan from the School of Metallurgy are the co-first authors of the paper.
Lithium metal batteries have a higher energy density and a broad application prospect in the new generation of electrochemical energy storage. Lithium metal, as a battery negative electrode, has a high theoretical capacity, but uneven deposition produced in the cycle process is easy to grow in the form of dendritic crystal. It shows poor stability and brings certain safety risks, thus restricting the development of lithium metal batteries. In this study, the growth of lithium dendritic crystal is inhibited by using high-crystallinity carbon nitride as a membrane modification layer. The extended conjugated structure in the high-crystallinity carbon nitride makes electron migration easier, and the interaction with lithium ion is enhanced by the chloride ion and the high content of pyrrole nitrogen in the structure. The experimental results show that the high-crystallinity carbon nitride modification layer can homogenize the ion flux, achieve even deposition of lithium, and improve the stability of symmetric batteries and Li//LiFePO4 batteries. This study has regulated carbon nitride materials through crystallinity engineering, expanded the application of carbon nitride-based materials in advanced battery systems, and provided new insights for the design of functional membranes for lithium metal batteries.
The Analysis and Testing Center of NEU has provided great support for the work of data collection and material characterization.
Figure: Structure of high-crystallinity carbon nitride and its application in lithium metal batteries