Recently, Professor Xiao Zhubing’s research group from the Henan Key Laboratory of Photovoltaic Materials has made research progress in high-performance lithium-sulfur batteries. The article is titled “Fluorine-Free Fabrication of MXene via Photo-Fenton Approach for Advanced Lithium-Sulfur Batteries” and published in the international journal ACS Nano (impact factor 15.881).
Two dimensional material MXene is widely used in lithium-sulfur batteries due to their unique physical and chemical properties. However, the conventional synthesis methods of MXene is using high concentration of hydrofluoric acid or fluorine-containing acidic solutions (mainly a mixture of hydrochloric acid and lithium fluoride) to selectively eliminate the A-element layers from the MAX phases. Despite the high efficiency, these processes make the preparation hazardous, and the inert -F terminal group can negatively affect the stability of the material. In this regard, it is necessary and important to explore a safer and more mild fluorine-free etching method. The article developed a low-temperature soft chemistry approach based on Photo-Fenton (P.F.) reaction for the fabrication of Ff-Ti3C2 MXene with high purity. A combined experimental and computational study confirmed that the continuous coexistence of reactive oxygen species (ROS, including HO• and O2•- radicals) weakens the metallic Ti-Al bonds and promotes the formation of high concentration OH- anions, which are beneficial for the sequential topochemical deintercalation of Al layers, resulting in highly hydrophilic Ff-Ti3C2 with high purity. Compared with the counterpart of F-terminalTi3C2 (F-Ti3C2), the rate performance and cycle performance of Ff-Ti3C2 have been greatly improved. More importantly, benefiting from the prominent electrolyte wettability, the flexible lithium-sulfur pouch cell show excellent electrochemical performance under high sulfur loading of 5.8 mg cm-2 and low electrolyte to sulfur ratio of 3.5 μL mg-1, delivering a high gravimetric energy density of 330 Wh kg-1 with decent cycling stability.
This work was financially supported by the Scientific Research Foundation for “Special Support Program for Exceptional Talents” of Henan University, National Natural Science Foundation of China, Key Scientific Research Projects of Higher Education in Henan Province, Natural Science Foundation of Henan Province, and Postdoctoral Foundation of Henan Province. The first author of the article is master student Liang Lin, and Professor Xiao Zhubing is the corresponding author.