Department of Materials Science, Fudan University , Shanghai 200433, China.
Shanghai Power & Energy Storage Battery System Engineering Tech. Co. Ltd. , Shanghai 200241, China.
ACS Appl Mater Interfaces. 2017 May 24;9(20):17145-17154. doi: 10.1021/acsami.7b03489. Epub 2017 May 11.
A commercial LiTiO material was modified by NHF using a facile and dry method at a low temperature in air. X-ray diffraction reveals that the fluorination did not change the bulk structure of LiTiO. X-ray photoelectron spectroscopy demonstrates that LiF was formed at the surface and Ti was partially changed into Ti. Microscopic images show that some nanoislands were formed on the surface, which enlarged the surface area. Consequently, the NHF-modified LiTiO material exhibited significantly enhanced capacities and rate capabilities, even at low temperatures. The discharge capacity was increased from 149 to 167 mA h g at 1 C, and the capacity retention was increased from 17.8 to 52.0% at 15 C. The capacity retention of NHF-modified LiTiO was greater than that of LiTiO at each low-temperature point. Additionally, the introduction of F can protect the LiTiO material from side reactions with the electrolyte and the atmosphere, enhancing the surface stability and reducing the release of gaseous products. It is believed that the NHF-modified LiTiO with enhanced electrochemical performance is a promising anode material for lithium ion batteries. Furthermore, this facile surface fluorination strategy is amenable to large-scale production.
采用简单的干法，在低温下，在空气中用 NHF 对商业 LiTiO 材料进行了改性。X 射线衍射表明，氟化没有改变 LiTiO 的体相结构。X 射线光电子能谱表明，在表面形成了 LiF，Ti 部分被转化为 Ti。微观图像显示，表面形成了一些纳米岛，从而增加了表面积。因此，NHF 改性的 LiTiO 材料表现出显著增强的容量和倍率性能，即使在低温下也是如此。在 1 C 时，放电容量从 149 mA h g 增加到 167 mA h g，在 15 C 时，容量保持率从 17.8%增加到 52.0%。在每个低温点，NHF 改性 LiTiO 的容量保持率都大于 LiTiO。此外，F 的引入可以保护 LiTiO 材料免受与电解液和大气的副反应，提高表面稳定性，减少气态产物的释放。人们相信，具有增强电化学性能的 NHF 改性 LiTiO 是一种很有前途的锂离子电池负极材料。此外，这种简单的表面氟化策略适合大规模生产。
