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Impact of Local Separation on the Structural and Electrochemical Behaviors in Li 2 MoO 3 LiCrO 2 Disordered Rock‐Salt Cathode Material
Author(s) -
Lee Hayeon,
Choi Woosung,
Lee Wontae,
Shim JaeHyun,
Kim YoungMin,
Yoon WonSub
Publication year - 2021
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.202002958
Subject(s) - materials science , redox , electrochemistry , cathode , dissociation (chemistry) , crystal structure , crystallography , diffusion , ion , chemical physics , electrode , chemistry , thermodynamics , physics , metallurgy , organic chemistry
Li‐excess disordered rock‐salt oxides have emerged as a promising group of cathode materials for Li‐ion batteries. However, the real cation distribution and short‐range order of various disordered oxides have not been fully determined, making it difficult to understand their actual structures and reaction processes. Here, Li 1.233 Mo 0.467 Cr 0.3 O 2 (LMCO), as a cathode material that undergoes a unique in situ cation‐disorder is investigated. Through synchrotron‐ and lab‐based multiscale characterizations, it is observed that the as‐prepared material has separate domains resembling Li 2 MoO 3 and LiCrO 2 even in a single‐phase bulk crystal structure. The Mo/Li‐rich and Cr/Li‐poor domains are maintained even after significant cation‐disorder. The formation and dissociation of short MoMo bonds along with a unique MoO 6 distortion in Mo/Li‐rich domain of disordered LMCO leads to minimal lattice parameter changes during Mo redox reactions. This phenomenon is intensified when the structure becomes more disordered owing to the dissipation of anisotropy. In disordered LMCO, the Mo 4+/6+ redox is highly reversible, while Cr 3+/4+ redox is not. Finally, based on the local separation that induces different 0‐TM diffusion abilities according to the different domains in disordered LMCO, the mechanisms of the domain‐dependent kinetics, asymmetric Li + diffusion, and linked hysteresis/degradation processes are explained.