A Novel High‐Performance TiO<sub>2‐x</sub>/TiO<sub>1‐y</sub>N<sub>y</sub> Coating Material for Silicon Anode in Lithium‐Ion Batteries
Sung Eun Wang, Min Ji Kim, Jin Woong Lee, Jinyoung Chun, Junghyun Choi, Kwang Chul Roh, Yun Chan Kang, Dae Soo Jung
Abstract
Abstract Protective surface coatings on Si anodes are promising for improving the electrochemical performance of lithium‐ion batteries (LIBs). Nevertheless, most coating materials have severe issues, including low initial coulombic efficiency, structural fracture, morphology control, and complicated synthetic processing. In this study, a multifunctional TiO 2‐ x /TiO 1‐ y N y (TTN) formed via a facile and scalable synthetic process is applied as a coating material for Si anodes. A thin layer of amorphous TiO 2 is uniformly coated onto Si nanoparticles by a simple sol–gel method and then converted into a two phase TiO 2‐ x /TiO 1‐ y N y via nitridation. The lithiated TiO 2‐x provides high ionic and electrical conductivity, while TiO 1‐y N y can improve mechanical strength that alleviates volume change of Si to address capacity fading issue. Owing to these synergetic advantages, TiO 2‐ x /TiO 1‐ y N y ‐coated Si (Si@TTN) exhibits excellent electrochemical properties, including a high charge capacity of 1650 mA h g –1 at 0.1 A g –1 and 84% capacity retention after 100 cycles at 1 A g –1 . Moreover, a significantly enhanced rate performance can be achieved at a high current density. This investigation presents a facile and effective coating material to use as the high‐capacity silicon anode in the emerging Si anode technology in LIBs.