Quantifying the Anomalous Local and Nanostructure Evolutions Induced by Lattice Oxygen Redox in Lithium‐Rich Cathodes. Issue 11 (30th September 2022)

• Record Type: Journal Article
• Authors: Zhao, Enyue; Wu, Kang; Zhang, Zhigang; Fu, Zhendong; Jiang, Hanqiu; Ke, Yubin; Yin, Wen; Ikeda, Kazutaka; Otomo, Toshiya; Wang, Fangwei; Zhao, Jinkui
• Is Part Of: Small methods. Volume 6:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-30
• Subjects: Li‐rich cathodes -- neutron characterization -- oxygen redox -- structure evolution; Nanotechnology -- Methodology -- Periodicals; Nanotechnology -- Periodicals; Periodicals; 620.5028
• DOI: 10.1002/smtd.202200740
• Languages: English
• ISSNs: 2366-9608

Abstract

Abstract: Due to their accessible lattice oxygen redox (l‐OR) at high voltages, Li‐rich layered transition metal (TM) oxides have shown promising potential as candidate cathodes for high‐energy‐density Li‐ion batteries. However, this l‐OR process is also associated with unusual electrochemical issues such as voltage hysteresis and long‐term voltage decay. The structure response mechanism to the l‐OR behavior also remains unclear, hindering rational structure optimizations that would enable practical Li‐rich cathodes. Here, this study reveals a strong coupling between l‐OR and structure dynamic evolutions, as well as their effects on the electrochemical properties. Using the technique of neutron total scattering with pair distribution function analysis and small‐angle neutron scattering, this study quantifies the local TM migration and formation of nanopores that accompany the l‐OR. These experiments demonstrate the causal relationships among l‐OR, the local/nanostructure evolutions, and the unusual electrochemistry. The TM migration triggered by the l‐OR can change local oxygen coordination environments, which results in voltage hysteresis. Coupled with formed oxygen vacancies, it will accelerate the formation of nanopores, inducing a phase transition, and leading to irreversible capacity and long‐cycling voltage fade. Abstract : Through neutron pair distribution function and small‐angle neutron scattering methods, the local cationic migration and nanopores formation accompanying the lattice oxygen redox in Li‐rich cathodes are quantified. The coupling relations among lattice oxygen redox, local/nanostructure evolutions, and unusual electrochemistry are constructed. This work highlights the role of tuning local/nanostructures in stabilizing the lattice oxygen redox.