Synthesis, structures and properties of the new lithium cobalt(II) phosphate Li{sub 4}Co(PO{sub 4}){sub 2}

Journal Article · Sun Apr 15 00:00:00 EDT 2012 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2012.01.054· OSTI ID:22012084

Glaum, R ^[1]; Gerber, K ^[1]; Schulz-Dobrick, M ^[2]; Herklotz, M; Scheiba, F; Ehrenberg, H ^[3]

---

1. Institut fuer Anorganische Chemie, Universitaet Bonn, Gerhard-Domagk-Strasse 1, D-53121 Bonn (Germany)
2. BASF SE, GCC/PS - M300, 67056 Ludwigshafen (Germany)
3. Institute for Complex Materials, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden (Germany)

{alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} has been synthesized and crystallized by solid-state reactions. The new phosphate crystallizes in the monoclinic system (P2{sub 1}/a, Z=4, a=8.117(3) Angstrom-Sign , b=10.303(8) Angstrom-Sign , c=8.118(8) Angstrom-Sign , {beta}=104.36(8) Angstrom-Sign ) and is isotypic to {alpha}-Li{sub 4}Zn(PO{sub 4}){sub 2}. The structure of {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} has been determined from single-crystal X-ray diffraction data {l_brace}R{sub 1}=0.040, wR{sub 2}=0.135, 2278 unique reflections with F{sub o}>4{sigma}(F{sub o}){r_brace}. The crystal structure, which might be regarded as a superstructure of the wurtzite structure type, is build of layers of regular CoO{sub 4}, PO{sub 4} and Li1O{sub 4} tetrahedra. Lithium atoms Li2, Li3 and Li4 are located between these layers. Thermal investigations by in-situ XRPD, DTA/TG and quenching experiments suggest decomposition followed by formation and phase transformation of Li{sub 4}Co(PO{sub 4}){sub 2}: {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} Long-Rightwards-Double-Arrow {sup 442 Degree-Sign C}{beta}-Li{sub 3}PO{sub 4}+LiCoPO{sub 4} Rightwards-Harpoon-Over-Leftwards-Harpoon {sup 773 Degree-Sign C}{beta}-Li{sub 4}Co(PO{sub 4}){sub 2} Long-Rightwards-Double-Arrow {sup quenchingto25 Degree-Sign C}{alpha}-Li{sub 4} Co(PO{sub 4}){sub 2} According to HT-XRPD at {theta}=850 Degree-Sign C{beta}-Li{sub 4}Co(PO{sub 4}){sub 2} (Pnma, Z=2, 10.3341(8) A, b=6.5829(5) A, c=5.0428(3) Angstrom-Sign ) is isostructural to {gamma}-Li{sub 3}PO{sub 4}. The powder reflectance spectrum of {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2} shows the typical absorption bands for the tetrahedral chromophore [Co{sup II}O{sub 4}]. - Graphical abstract: The complex formation and decomposition behavior of Li{sub 4}Co(PO{sub 4}){sub 2} with temperature has been elucidated. The crystal structure of its {alpha}-phase was determined from single crystal data, HT-XRPD allowed derivation of a structure model for the {beta}-phase. Both modifications belong to the Li{sub 3}PO{sub 4} structure family. Highlights: Black-Right-Pointing-Pointer Li{sub 4}Co(PO{sub 4}){sub 2} exhibits complex thermal behavior. Black-Right-Pointing-Pointer The new phosphate belongs to the Li{sub 3}PO{sub 4} structure family. Black-Right-Pointing-Pointer A single-crystal structure analysis is provided for the metastable {alpha}-Li{sub 4}Co(PO{sub 4}){sub 2}. Black-Right-Pointing-Pointer From HT-XRPD data a cation distribution model is developed for {beta}-Li{sub 4}Co(PO{sub 4}){sub 2}. Black-Right-Pointing-Pointer No electrochemical delithiation is observed up to 5 V.

• OSTI ID: 22012084
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. . 188; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ABSORPTION
CATHODES
COBALT
DECOMPOSITION
DIFFERENTIAL THERMAL ANALYSIS
DISTRIBUTION
ELECTROCHEMISTRY
LAYERS
LITHIUM
LITHIUM PHOSPHATES
MONOCLINIC LATTICES
MONOCRYSTALS
ORTHORHOMBIC LATTICES
PHASE TRANSFORMATIONS
POWDERS
SOLIDS
SPECTRA
SPECTROSCOPY
SYNTHESIS
X-RAY DIFFRACTION