Structural characterization of layered Li{sub x}Ni{sub 0.5}Mn{sub 0.5}O{sub 2}(0
X-ray diffraction and X-ray absorption spectroscopy experiments were used to study chemical and electrochemical Li insertion and extraction reactions of LiNi{sub 0.5}Mn{sub 0.5}O{sub 2}. These results, along with galvanostatic cycling data, suggest that LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} layered electrodes in lithium batteries operate predominantly off two-electron redox couples, Ni{sup 4+}/Ni{sup 2+}, between approximately 4.5 and 1.25 V and Mn{sup 4+}/Mn{sup 2+} between 1.25 and 1.0 V versus metallic Li, respectively. The retention of a stable layered framework structure and the apparent absence of Jahn-Teller ions Ni{sup 3+} and Mn{sup 3+} in the high- or low-voltage region is believed to be responsible for the excellent structural and electrochemical stability of these electrodes. The LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} layered oxide reversibly reacts chemically or electrochemically with Li to form an air-sensitive, dilithium compound, Li{sub 2}Ni{sub 0.5}Mn{sub 0.5}O{sub 2}, with a hexagonal structure analogous to Li{sub 2}MnO{sub 2}. The cycling behavior of Li/LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} cells over a large voltage window (4.6-1.0 V) and with very slow rates shows that rechargeable capacities >500 mA{center_dot}h/g can be obtained.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); EE
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 961266
- Report Number(s):
- ANL/CMT/JA-45953; CMATEX; TRN: US201011%%539
- Journal Information:
- Chem. Mater., Vol. 15, Issue 12 ; 2003; ISSN 0897-4756
- Country of Publication:
- United States
- Language:
- ENGLISH
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