Elucidation of the Co4+ State with Strong Charge-Transfer Effects in Charged LiCoO2 by Resonant Soft X-ray Emission Spectroscopy at the Co L3 edge

IF 2.9 3区化学 Q3 CHEMISTRY, PHYSICAL

Physical Chemistry Chemical Physics Pub Date : 2024-12-10 DOI:10.1039/d4cp03759f

Daisuke Asakura, Takaaki Sudayama, Yusuke Nanba, Eiji Hosono, Hisao Kiuchi, Kosuke Yamazoe, Jun Miyawaki, Yoshihisa Harada, Atsuo Yamada, Ru-Pan Wang, Frank M F de Groot

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引用次数: 0

Abstract

To understand the electronic-structure change of LiCoO₂, a widely used cathode material in Li-ion batteries, during charge–discharge, we performed ex situ soft X-ray absorption spectroscopy (XAS) and resonant soft X-ray emission spectroscopy (RXES) of the Co L₃ edge in combination with charge-transfer multiplet calculations. The RXES profile significantly changed for the charged state at 4.2 V vs. Li/Li⁺, corresponding to the oxidation reaction from a Co³⁺ low-spin state for the initial state, while the XAS profile exhibited small changes. For the 4.2-V charged state, we confirmed that approximately half of the initial Co³⁺ ions were oxidized to Co⁴⁺ ions. The multiplet calculation of the RXES results revealed that the Co⁴⁺ state has a negative charge-transfer energy and the d⁶L state (L is a ligand hole) is the most stable. Therefore, the O 2p hole created by the strong charge-transfer effect plays a major role in the redox reaction of LiCoO₂.

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通过 Co L3 边的共振软 X 射线发射光谱阐明带电钴酸锂中具有强电荷转移效应的 Co4+ 态

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来源期刊

Physical Chemistry Chemical Physics 化学-物理：原子、分子和化学物理

CiteScore

5.50

自引率

9.10%

发文量

2675

审稿时长

2.0 months

期刊介绍： Physical Chemistry Chemical Physics (PCCP) is an international journal co-owned by 19 physical chemistry and physics societies from around the world. This journal publishes original, cutting-edge research in physical chemistry, chemical physics and biophysical chemistry. To be suitable for publication in PCCP, articles must include significant innovation and/or insight into physical chemistry; this is the most important criterion that reviewers and Editors will judge against when evaluating submissions. The journal has a broad scope and welcomes contributions spanning experiment, theory, computation and data science. Topical coverage includes spectroscopy, dynamics, kinetics, statistical mechanics, thermodynamics, electrochemistry, catalysis, surface science, quantum mechanics, quantum computing and machine learning. Interdisciplinary research areas such as polymers and soft matter, materials, nanoscience, energy, surfaces/interfaces, and biophysical chemistry are welcomed if they demonstrate significant innovation and/or insight into physical chemistry. Joined experimental/theoretical studies are particularly appreciated when complementary and based on up-to-date approaches.