Preparation of intergrown P/O-type biphasic layered oxides as high-performance cathodes for sodium ion batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 9; no. 22; pp. 13151 - 1316
• Main Authors: Wang, Kai, Wu, Zhen-Guo, Melinte, Georgian, Yang, Zu-Guang, Sarkar, Abhishek, Hua, Weibo, Mu, Xiaoke, Yin, Zu-Wei, Li, Jun-Tao, Guo, Xiao-Dong, Zhong, Ben-He, Kübel, Christian
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14.06.2021
• Subjects: Cathodes; Electrochemistry; Electrode materials; Metal concentrations; Phases; Sodium; Sodium-ion batteries; Transition metals; Transmission electron microscopy
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d1ta00627d

This study reports on the solid-state synthesis and characterization of novel quaternary P/O intergrown biphasic Na 0.8 Mn y Ni 0.8− y Fe 0.1 Ti 0.1 O 2 ( y = 0.6, 0.55, 0.5, 0.45) cathode materials. Electrochemical tests reveal superior performance of the P/O biphasic materials in a sodium ion battery compared to the single P2 or O3 phases, proving the beneficial effect of the intergrowth of P2 and O3 materials. The nature of the P/O interface was studied by transmission electron microscopy. The analysis shows a semi-coherent interface grown along the a / b and c axes with local differences in the transition metal concentration along the interface between the two phases. EDX and EELS characterization revealed a charge compensation mechanism across the phase boundary based on variation of the transition element distribution, balancing the different sodium contents in the P and O phases. The results reported in this study provide a better understanding of P/O biphasic materials. P/O intergrown biphasic sodium cathode materials with improved electrochem. properties were prepared. TEM revealed a semi-coherent interface with uniform oxidation state but different metal concentrations balancing sodium concentration differences.