Probing Dopant Redistribution, Phase Propagation, and Local Chemical Changes in the Synthesis of Layered Oxide Battery Cathodes. Issue 1 (20th November 2020)

• Record Type: Journal Article
• Authors: Yang, Zhijie; Mu, Linqin; Hou, Dong; Rahman, Muhammad Mominur; Xu, Zhengrui; Liu, Jue; Nordlund, Dennis; Sun, Cheng‐Jun; Xiao, Xianghui; Lin, Feng
• Is Part Of: Advanced energy materials. Volume 11:Issue 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-20
• Subjects: calcination -- Co free -- dopant distribution -- layered oxides -- Li‐ion batteries; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202002719
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Achieving the targeted control of layered oxide properties calls for more fundamental studies to mechanistically probe their evolution during their synthesis. Herein, dopant distribution, phase propagation, and local chemical changes as well as their interplay in multielement‐doped LiNiO2 materials are investigated using spectroscopic, imaging, and scattering techniques. It is shown that dopants undergo dynamic redistribution in the Ni(OH)2 host lattice at the early stage of calcination (below 300 °C). Such redistribution behavior exhibits strong dopant‐dependent characteristics, allowing for targeted surface and bulk doping control. The Ni oxidation process exhibits depth‐dependent characteristics and the most rapid Ni oxidation takes place between 300 and 700 °C. Using Ni oxidation state as the proxy for the phase transformation, the buildup of heterogenous phase propagation in the early stage of calcination is shown, especially along the radial direction of secondary particles. The radial heterogenous phase distribution gradually decreases upon completing the calcination. However, a high degree of mosaic‐like heterogeneity may still be present in the final product, departing from the perfect layered oxide. The present study offers fundamental insights into manipulating multiscale materials properties during calcination for obtaining stable, high‐energy layered oxide cathodes. Abstract : Dopant redistribution, phase transformation, and local chemical environment changes during layered cathode synthesis are probed at multiple length scales. Complementary characterization results suggest that the inward dopant diffusion takes place below 300 °C, which is long before the layered oxide formation. Transition metal oxidation and phase propagation are depth‐dependent and heterogenous, including both radial and mosaic‐like heterogeneity patterns.