In situ Raman spectroscopy reveals the mechanism of titanium substitution in P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2): Cathode materials for sodium batteries

作     者：Xiao-Bin Zhong Chao He Fan Gao Zhong-Qun Tian Jian-Feng Li Xiao-Bin Zhong;Chao He;Fan Gao;Zhong-Qun Tian;Jian-Feng Li

作者机构：School of Mechanical and Power EngineeringNorth University of ChinaTaiyuan 030051ShanxiChina State Key Laboratory of Physical Chemistry of Solid SurfacesCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005FujianChina 

出 版 物：《Journal of Energy Chemistry》 (能源化学（英文版）)

年 卷 期：2021年第30卷第2期

页      面：323-328,I0011页

核心收录：

学科分类：0820[工学-石油与天然气工程] 081702[工学-化学工艺] 0808[工学-电气工程] 07[理学] 08[工学] 0817[工学-化学工程与技术] 0807[工学-动力工程及工程热物理] 070302[理学-分析化学] 0827[工学-核科学与技术] 0703[理学-化学] 

基　　金：supported by the NSFC (21905239, 21925404, and 21775127) the Natural Science Foundation of Shanxi Province of China (201901D211265) the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi (2019L0609)。 

主　　题：In situ Raman spectroscopy P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2) Titanium substitution 

摘      要：Layered P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 is a promising cathode material. It exhibits a high capacity and suitable operating voltage and undergoes a phase transition from P2 to O2 during charge/discharge.Researchers have used Ti substitution to improve the cathode, yet the chemical principles that underpin elemental substitution and functional improvement remain unclear. To clarify these principles, we used in situ Raman spectroscopy to monitor chemical changes in P2–Na2/3 Ni1/3 Mn1/3 Ti1/3 O2 and P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_2 during charge/discharge. Based on the change in the A_(1g) and E_g peaks during charge/discharge, we concluded that Ti substitution compressed the transition metal layer and expanded the planar oxygen layer in the unit cell. Titanium stabilized the P2 phase structure, which improved the cycling stability of P2–NaNMT. Our results provide clear theoretical support for future research on modifying electrodes by elemental substitution.