Mitigation of Jahn–Teller distortion and Na+/vacancy ordering in a distorted manganese oxide cathode material by Li substitution. Issue 3 (24th November 2020)

• Record Type: Journal Article
• Authors: Liu, Yanchen; Wang, Chenchen; Zhao, Shuo; Zhang, Lin; Zhang, Kai; Li, Fujun; Chen, Jun
• Is Part Of: Chemical science. Volume 12:Issue 3(2021)
• Page Start: 1062
• Page End: 1067
• Publication Date: 2020-11-24
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/d0sc05427e
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Li-Substitution in P′2-Na0.67 MnO2 mitigates the anisotropic change of Mn–O bonds and Na/vacancy ordering, and hence significantly promotes its cycling stability and rate capability as a cathode material for sodium-ion batteries. Abstract : Layered manganese-based oxides are promising candidates as cathode materials for sodium-ion batteries (SIBs) due to their low cost and high specific capacity. However, the Jahn–Teller distortion from high-spin Mn 3+ induces detrimental lattice strain and severe structural degradation during sodiation and desodiation. Herein, lithium is introduced to partially substitute manganese ions to form distorted P′2-Na0.67 Li0.05 Mn0.95 O2, which leads to restrained anisotropic change of Mn–O bond lengths and reinforced bond strength in the [MnO6 ] octahedra by mitigation of Jahn–Teller distortion and contraction of MnO2 layers. This ensures the structural stability during charge and discharge of P′2-Na0.67 Li0.05 Mn0.95 O2 and Na + /vacancy disordering for facile Na + diffusion in the Na layers with a low activation energy barrier of ∼0.53 eV. It exhibits a high specific capacity of 192.2 mA h g −1, good cycling stability (90.3% capacity retention after 100 cycles) and superior rate capability (118.5 mA h g −1 at 1.0 A g −1 ), as well as smooth charge/discharge profiles. This strategy is effective to tune the crystal structure of layered oxide cathodes for SIBs with high performance.