Qian Kun, Tang Linkai, Wagemaker Marnix, He Yan-Bing, Liu Dongqing, Li Hai, Shi Ruiying, Li Baohua, Kang Feiyu
Nano Energy Materials Laboratory (NEM) Tsinghua-Berkeley Shenzhen Institute (TBSI) Tsinghua University Shenzhen 518055 P. R. China.
Laboratory of Advanced Materials School of Materials Science and Engineeing Tsinghua University Beijing 100086 P. R. China.
Adv Sci (Weinh). 2017 Jul 10;4(11):1700205. doi: 10.1002/advs.201700205. eCollection 2017 Nov.
Through a facile sodium sulfide (NaS)-assisted hydrothermal treatment, clean and nondefective surfaces are constructed on micrometer-sized LiTiO particles. The remarkable improvement of surface quality shows a higher first cycle Coulombic efficiency (≈95%), a significantly enhanced cycling performance, and a better rate capability in electrochemical measurements. A combined study of Raman spectroscopy and inductive coupled plasma emission spectroscopy reveals that the evolution of LiTiO surface in a water-based hydrothermal environment is a hydrolysis-recrystallization process, which can introduce a new phase of anatase-TiO. While, with a small amount of NaS (0.004 mol L at least), the spinel-LiTiO phase is maintained without a second phase. During this process, the alkaline environment created by NaS and the surface adsorption of the sulfur-containing group (HS or S) can suppress the recrystallization of anatase-TiO and renew the particle surfaces. This finding gives a better understanding of the surface-property relationship on LiTiO and guidance on preparation and modification of electrode material other than coating or doping.
通过简便的硫化钠（NaS）辅助水热处理，在微米级LiTiO颗粒上构建了清洁且无缺陷的表面。表面质量的显著改善表现为首次循环库仑效率更高（约95%）、循环性能显著增强以及在电化学测量中具有更好的倍率性能。拉曼光谱和电感耦合等离子体发射光谱的联合研究表明，LiTiO表面在水基水热环境中的演变是一个水解 - 重结晶过程，这会引入锐钛矿型TiO的新相。然而，使用少量的NaS（至少0.004 mol L）时，尖晶石型LiTiO相得以保持而无第二相。在此过程中，由NaS产生的碱性环境以及含硫基团（HS或S）的表面吸附可以抑制锐钛矿型TiO的重结晶并更新颗粒表面。这一发现有助于更好地理解LiTiO上的表面 - 性质关系，并为除涂层或掺杂之外的电极材料制备和改性提供指导。
