Deciphering anomalous zinc ion storage in intermediate-state MnO2 during layer-to-tunnel structural transition

MnO2 materials have attracted intensive attention as cathode materials for aqueous zinc ion batteries (AZIBs) owing to their outstanding structural diversity, decent capacity and competitive cost. Although various types of MnO2 have been adopted, none of them completely meet practical demands owing...

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Published in:Energy & environmental science 2024-11, Vol.17 (23), p.9195-9204
Main Authors: Li, Xiaohui, He, Dayin, Zhou, Qiancheng, Zhou, Xing, Wang, Zhouzhou, Wei, Chenchen, Shi, Yaran, Hu, Xiyang, Huang, Bangwang, Yang, Ze, Han, Xiao, Lin, Yue, Yu, Ying
Format: Article
Language:English
Subjects:
Cathodes
Competitive materials
Cycles
Deformation effects
Electrode materials
Ion storage
Jahn-Teller effect
Manganese dioxide
Manganese ions
Orbital stability
Phase transitions
Structural analysis
Valence
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Summary:MnO2 materials have attracted intensive attention as cathode materials for aqueous zinc ion batteries (AZIBs) owing to their outstanding structural diversity, decent capacity and competitive cost. Although various types of MnO2 have been adopted, none of them completely meet practical demands owing to structural collapse during cycling. Herein, intermediate-state MnO2 (IS-MnO2) undergoing a transition from a layered to a tunnel structure is reported, which exhibits significant improvements in rate and cycling performance compared with purely layered or tunnel MnO2. Systemic structural analysis reveals the presence of abundant two-phase transition regions within IS-MnO2, which results in a distorted lattice and deformed [MnO6] octahedron unit within the two-phase transition region as well as a reduced average valence state of Mn ions. The deformation of [MnO6] reduces the geometric symmetry of the ligand field and thereby eliminates the 3d orbital degeneracy of the center Mn ion, which effectively avoids the Jahn–Teller effect of Mn3+ and enhances cycling stability. Additionally, low-valence Mn leads to a decrease in electrostatic repulsion during ion insertion/extraction, thus efficiently improving rate performance. This work presents a high-performance cathode for AZIBs and provides new avenues to eliminate the Jahn–Teller effect of Mn3+.
ISSN:1754-5692
1754-5706
DOI:10.1039/d4ee03293d