A fundamental understanding of the Fe/Ti doping induced structure formation process to realize controlled synthesis of layer-tunnel Na0.6MnO2 cathode. (April 2020)

• Record Type: Journal Article
• Authors: Wang, Dong; Shi, Chenguang; Deng, Ya-Ping; Wu, Zhenguo; Yang, Zuguang; Zhong, Yanjun; Jiang, Yi; Zhong, Benhe; Huang, Ling; Guo, Xiaodong; Chen, Zhongwei
• Is Part Of: Nano energy. Volume 70(2020)
• Publication Date: 2020-04
• Subjects: Sodium-ion batteries -- Cathode -- Composite structure -- Layer-tunnel -- Formation process; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2020.104539
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: It's well known that ion-doping could modify the crystal structure and adjust the corresponding performance of cathode, but how the doped ions affect the structure formations during high-temperature calcination still remains a daunting challenge, which is critical for the ideal controlled synthesis. In our pervious study, we have found that the cationic ion doping can both tune the single phase structure and adjust the phase ratio in layer-tunnel Na0.6 MnO2 . And in the present study, we furtherly try to track the influence of varied Fe 3+ and Ti 4+ on the formation process of layer-tunnel hybrid structures and focus on the thermal behavior, structure evolution and morphology change. The kinetics-preferred layered structure can be detected at the initial stage and transfer to the thermodynamic-stable tunnel structure at increased temperature. The Fe 3+ can stabilize the formed layer structure while the Ti 4+ promote the latter transformation. More interesting, the Ti 4+ plays a dominant role when Fe 3+ /Ti 4+ were co-doped. The impressive results can be related with the more orderly structure of layer phase and distorted coordination in tunnel phase. This research correlates the synthesis process and the final structure, as well as the ultimate electrochemical performance, which shed new light on the development of advanced oxides cathode. Graphical abstract: The layer-tunnel composite structure formation process was systematically and deeply investigated from both thermal dynamics and reaction kinetics aspects. And controlled structure modulation can be realized by different ion-doping (Fe 3+ /Ti 4+ ) to obtain final P2 layer-tunnel composite structure with superior performance. Layer to tunnel phase transition at high temperature was detected and promoted or hindered via Fe 3+ /Ti 4+ doping. And Ti 4+ plays a more important role in the structure tuning process. Image 1 Highlights: The Fe/Ti doped layer-tunnel composite structure formation process was studied by in-situ experiment and theory method. Fe/Ti can hinder/promote the layer to tunnel transformation under high-temperature. With the controlled structure formation process, the final products achieved outstanding electrochemical performance.