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 

机构地区：[1]School of Mechanical and Power Engineering,North University of China,Taiyuan 030051,Shanxi,China [2]State Key Laboratory of Physical Chemistry of Solid Surfaces,College of Chemistry and Chemical Engineering,Xiamen University,Xiamen 361005,Fujian,China

出　　处：《Journal of Energy Chemistry》2021年第2期323-328,I0011,共7页能源化学（英文版）

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)。

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.

关 键 词：In situ Raman spectroscopy P2–Na_(2/3)Ni_(1/3)Mn_(2/3)O_(2) Titanium substitution 

分 类 号：TM912[电气工程—电力电子与电力传动] TQ131.12[化学工程—无机化工] O657.37[理学—分析化学]