Structural characterization of layered LiMnO{sub 2} electrodes by electron diffraction and lattice imaging
- Michigan Technological Univ., Houghton, MI (United States). Dept. of Metallurgical and Materials Engineering
- Univ. of St. Andrews, Fife (United Kingdom). School of Chemistry
- Argonne National Lab., IL (United States). Chemical Technology Div.
Electrode materials of the formula LiMnO{sub 2} were prepared by an ion-exchange process from {alpha}-NaMnO{sub 2} and were examined by X-ray diffraction and convergent-beam electron diffraction to determine crystal structure and phase purity. Electron diffraction data showed that a typical parent LiMnO{sub 2} sample consisted predominantly of layered LiMnO{sub 2} (C2/m) with lithiated-spinel Li{sub 2}[Mn{sub 2}]O{sub 4} (F4{sub 1}/ddm) present in minor concentration; orthorhombic LiMnO{sub 2} (Pmmm) was detected in trace quantity. An orientation relationship between the monoclinic layered LiMnO{sub 2} and tetragonal lithiated-spinel Li{sub 2}[Mn{sub 2}]O{sub 4} was obtained from an analysis of single-crystal electron diffraction data. Electron diffraction analyses of three electrochemically cycled Li{sub x}MnO{sub 2} (0 < x < 1) samples showed that the parent compound was unstable to repeated lithium intercalation/deintercalation and transformed to a spinel-type structure, consistent with previous reports. These Li{sub x}MnO{sub 2} electrodes, like those derived from orthorhombic-LiMnO{sub 2}, show greater stability compared to standard Li{sub y}[Mn{sub 2}]O{sub 4} spinel electrodes, when cycled between 4.6 and 2.0 V. The unexpected stability of the Li{sub x}MnO{sub 2} electrodes (0.5 {le} x < 1.0) at 3 V is attributed to the presence of Li{sub 1+z}Mn{sub 2{minus}z}O{sub 4} spinel domains (0 < z < 0.33) in a composite electrode structure.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 680038
- Journal Information:
- Journal of the Electrochemical Society, Vol. 146, Issue 7; Other Information: PBD: Jul 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Electrochemical cycling-induced spinel formation in high-charge-capacity orthorhombic LiMnO{sub 2}
Electrochemical cyclability of orthorhombic LiMnO{sub 2}: Characterization of cycled materials