Phase diagram of Li-Mn-O spinel in air
Thermogravimetric analysis, solid electrolyte coulometry, and X-ray diffraction were used to examine the stable phases in the Li-Mn-O phase diagram. Their investigations concentrated on the equilibrium composition of the spinel phase in the system Li-Mn-O. Between 400 and 880 C only spinel with the composition Li{sub 1+x}Mn{sub 2{minus}x}O{sub 4+{delta}} ({delta}{approximately}0) is stable. The lithium stoichiometry, x, is a function of temperature, T, and oxygen partial pressure, p(O{sub 2}). The value of x increases with decreasing temperature and increasing p(O{sub 2}). The possible lithium stoichiometry range, {Delta}x, at a given T and a given p(O{sub 2}) is much smaller than generally accepted. They find that 0.05 {le} {Delta}x {le} 0.13. The spinel Li{sub 1+x}Mn{sub 2{minus}x}O{sub 4+{delta}} has a negligible oxygen nonstoichiometric range, {delta} {le} 0.02. Between 880 and 980 C a variety of different tetragonal Li-Mn spinel phases Li{sub 1{minus}x}Mn{sub 2+x}O{sub 4} exist. Though commonly attributed as oxygen and lithium deficient spinel, their results indicate the absence of any significant oxygen deficiency. Below 400 C spinel appears to be stable only as Li{sub 4}Mn{sub 5}O{sub 12} and LiMn{sub 1.75}O{sub 4}. A phase diagram of the second kind is presented for the Li-Mn-O system.
- Research Organization:
- Dalhousie Univ., Halifax, Nova Scotia (CA)
- OSTI ID:
- 20004023
- Journal Information:
- Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 11 Vol. 11; ISSN CMATEX; ISSN 0897-4756
- Country of Publication:
- United States
- Language:
- English
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