Powder diffraction study of LiCu 2 O 2 crystals
TL;DR: LiCu 2 O 2 crystals were studied by powder X-ray diffraction and phase analysis showed that the applied growth conditions are suitable for preparation of a single-phase compound.
Abstract: LiCu 2 O 2 crystals grown by spontaneous crystallization from the fluxed melt were studied by powder X-ray diffraction. The phase analysis shows that the applied growth conditions are suitable for preparation of a single-phase compound. The as-grown crystals contain only traces of foreign phases (Li 2 CuO 2 , CuO, Cu 2 O) typical for preparation of the LiCu 2 O 2 compound. Attempts to anneal or quench the as-grown crystals led to two-phase samples containing LiCu 2 O 2 and LiCu 3 O 3 . X-ray powder diffraction pattern of a LiCu 2 O 2 crystal is reported and compared with literature data. The crystal structure is orthorhombic, space group Pnma , in agreement with literature data. Lattice parameters of the studied sample are a =5.7286(2) A, b =2.8588(1) A, and c =12.4143(3) A. Time evolution of a diffraction pattern illustrates a slow increase of the secondary-phases contribution assumed to be due to interaction of the powdered crystal with humid air. A brief summary of compounds known in the Li–Cu–O system is included
Citations
More filters
TL;DR: In this paper, a complete set of local excitations has been calculated for cuprates with corner sharing (Sr${}_{2}$CuO${}_3}$ and SrCuO{}_4}$) and edge-sharing (LiVCuO={}_6}$ octahedra (KCuF${} ǫ ) for the ladder system CaCu{} Ã 0.
Abstract: With wave-function-based electronic-structure calculations we determine the Cu $d$-$d$ excitation energies in quasi-one-dimensional spin-chain and ladder copper oxides. A complete set of local excitations has been calculated for cuprates with corner-sharing (Sr${}_{2}$CuO${}_{3}$ and SrCuO${}_{2}$) and edge-sharing (LiVCuO${}_{4}$, CuGeO${}_{3}$, LiCu${}_{2}$O${}_{2}$, and Li${}_{2}$CuO${}_{2}$) CuO${}_{4}$ plaquettes, with corner-sharing CuF${}_{6}$ octahedra (KCuF${}_{3}$), for the ladder system CaCu${}_{2}$O${}_{3}$, and for multiferroic cupric oxide CuO. Our data compare well with available results of optical absorption measurements on KCuF${}_{3}$ and the excitation energies found by resonant inelastic x-ray scattering experiments for CuO. The ab initio results we report for the other materials should be helpful for the interpretation of future resonant inelastic x-ray scattering experiments on those highly anisotropic compounds.
24 citations
TL;DR: In this paper, the LiCu2O2 phase was synthesized using the solid-state method and characterized with X-ray powder diffraction technique and Rietveld analysis as well as inductively coupled plasma-optical emission spectrometry (ICP-OES).
Abstract: Copper oxides, which exhibit the conversion mechanism with lithium during electrochemical cycling, are promising electrode materials for next-generation lithium ion batteries. To better understand phase formations and equilibria in the Li–Cu–O system, the LiCu2O2 phase was synthesized using the solid-state method and characterized with X-ray powder diffraction technique and Rietveld analysis as well as inductively coupled plasma—optical emission spectrometry (ICP–OES). The phase stabilities in argon atmosphere and in a mixture of argon and oxygen were determined between 200 and 900 °C and between 200 and 950 °C, respectively. Based on this data as well as on other literature data, a thermodynamic description of the Li–Cu–O system valid in the battery relevant temperature regime was developed using the CALPHAD method. From this thermodynamic description, titration curves for CuO and Cu2O cathodes, which give the equilibrium cell voltage as a function of lithium content along a selected composition path, were calculated at different temperatures.
12 citations
TL;DR: In this paper, a plate-like Li1 − xNaxCu2O2 single crystals up to 2 × 10 × 10 mm in dimensions have been grown by slowly cooling Li2CO3·xNa2O 2·4CuO melts in alundum crucibles in air.
Abstract: Platelike Li1 − xNaxCu2O2 single crystals up to 2 × 10 × 10 mm in dimensions have been grown by slowly cooling (1 − x)Li2CO3·xNa2O2·4CuO melts in alundum crucibles in air. Li1 − xNaxCu2O2 solid solutions in the LiCu2O2-NaCu2O2 system have been shown to exist in the composition range 0.78 < x < 1. The temperature stability ranges of NaCu2O2 and LiCu2O2 are 780–930 and 890–1050°C, respectively. The Mossbauer spectra and electrical conductivity of the crystals have been measured.
6 citations
15 Dec 2016
TL;DR: In this article, a thermodynamic approach was used to elucidate the electrochemical behavior of conversion-type electrodes using Li-Cu-O and Li-Fe-O as model material systems.
Abstract: Konversionselektroden sind vielversprechende Elektrodenmaterialien fur zukunftige Lithium-Ionen-Batterien, da sie sehr hohe spezifische Kapazitaten im Vergleich zu Interkalationselektroden aufweisen. In dieser Arbeit wird ein thermodynamischer Ansatz gewahlt, um den elektrochemischen Prozess von Konversions-Elektroden anhand der Modell-Systeme Li-Cu-O und Li-Fe-O zu beleuchten. Mit den konsistenten thermodynamischen Beschreibungen konnen elektrochemische Eigenschaften berechnet werden. Conversion-type electrodes are promising electrode materials for future lithium ion batteries since they exhibit high specific capacities compared to intercalation-type eclectrodes. In this work, a thermodynamic approach was used to elucidate the electrochemical behavior of conversion-type electrodes using Li-Cu-O and Li-Fe-O as model material systems. electrochemical properties can be calculated using self-sonstistent thermodynamic descriptions developed in this work. Umfang: XVI, 291 S. Preis: €48.00 | £44.00 | $84.00
5 citations
Cites background from "Powder diffraction study of LiCu 2 ..."
...In der Literatur wird häufig davon berichtet, dass es schwierig sei, einphasige ternäre Proben im System Li-Cu-O , insbesondere Verbindungen, die gemischte Oxidationsstufen des Kupferkations besitzen, herzustellen [128, 131, 146, 147, 162, 163]....
[...]
...[147] schreibt, dass während der Synthese von LiCu2O2 typischerweise die Fremdphasen Li2CuO2, CuO und Cu2O auftreten....
[...]
...Eine orthorhombische Struktur wurde durch Untersuchungen weiterer Gruppen [131, 146, 147] bestätigt....
[...]
...LiCu2O2 890 - 1050 °C in Luft Pnma [131, 146, 147]...
[...]
TL;DR: In this article, differential scanning calorimetry was used to measure the heat capacities of binary and ternary oxides in the Li-Cu-O system for the development of new anode materials for lithium ion batteries based on copper oxides.
Abstract: The Li-Cu-O system is a promising materials system for the development of new anode materials for lithium ion batteries based on copper oxides. The specific heat capacities of binary and ternary oxides in this system are required to generate thermodynamic descriptions using the CALPHAD method. Additionally, heat capacity data can be used to support development of thermal management systems for the lithium ion batteries based on these materials. In this study, differential scanning calorimetry was used to measure the heat capacities of the binary copper oxides and of the ternary LiCu2O2. The heat capacity of CuO was measured from 323 to 773 K and that of Cu2O was measured from 973 to 1273 K. The heat capacity of CuO is in good agreement with literature data. However, the heat capacity of Cu2O is slightly lower than that calculated using CALPHAD-based thermodynamic descriptions of the Cu-O system but higher than that determined using ab initio calculations. Although the synthesis of single phase LiCu2O2 is difficult because of the mixed oxidation states of Cu, our heat capacity measurements show that the constituent additivity method can be used to estimate the heat capacity of LiCu2O2.
4 citations
References
More filters
1,804 citations
TL;DR: In this article, the average voltage to intercalate lithium in various metal oxides was studied and it was found that Li is fully ionized in the intercalated compounds with its charge transferred to the anion and to the metal.
Abstract: A study of the average voltage to intercalate lithium in various metal oxides is presented. By combining the ab initio pseudopotential method with basic thermodynamics the average intercalation voltage can be predicted without the need for experimental data. This procedure is used to systematically study the effect of metal chemistry, anion chemistry, and structure. It is found that Li is fully ionized in the intercalated compounds with its charge transferred to the anion and to the metal. The substantial charge transfer to the anion is responsible for the large voltage difference between oxides, sulfides, and selenides. Ionic relaxation, as a result of Li intercalation, causes nonrigid-band effects in the density of states of these materials. Suggestions for compounds that may have a substantially larger voltage than currently used materials are also presented. @S0163-1829~97!01028-X#
1,158 citations
TL;DR: In this paper, the optical conductivity and magnetic properties of edge-sharing Cu-O chains were analyzed for single-crystalline samples and the exact diagonalization method was used to analyze the magnetic properties.
Abstract: The electronic states and magnetic properties for the copper oxides containing edge-sharing Cu-O chains such as ${\mathrm{Li}}_{2}{\mathrm{CuO}}_{2}$, ${\mathrm{La}}_{6}{\mathrm{Ca}}_{8}{\mathrm{Cu}}_{24}{\mathrm{O}}_{41}$, and ${\mathrm{CuGeO}}_{3}$ are systematically studied. The optical conductivity $\ensuremath{\sigma}(\ensuremath{\omega})$ and the temperature dependence of the magnetic susceptibility $\ensuremath{\chi}(T)$ for single-crystalline samples ${\mathrm{Li}}_{2}{\mathrm{CuO}}_{2}$ are measured as a reference system and analyzed by using the exact diagonalization method for small Cu-O clusters. It is shown that the spectral distribution of $\ensuremath{\sigma}(\ensuremath{\omega})$ is different between edge-sharing and corner-sharing Cu-O-Cu bonds. The charge transfer gap in edge-sharing chains is larger than that of high-${T}_{\mathrm{c}}$ cuprates. The exchange interaction between nearest-neighbor copper ions in edge-sharing chains ${J}_{1}$ depends sensitively on the Cu-O-Cu bond angles. In addition to ${J}_{1}$, the exchange interaction between next-nearest-neighbor copper ions ${J}_{2}$ has sufficient contribution to the magnetic properties. We calculate ${J}_{1}$ and ${J}_{2}$ for all the copper oxides containing edge-sharing Cu-O chains and discuss the magnetic properties.
228 citations
TL;DR: In this article, a single-crystal X-ray diffraction study confirmed the trigonalR3mspace group and the lattice parametersa=2.8161(5) A andc=14.0536(5)-A in the CoO6 octahedron.
167 citations
TL;DR: In this article, the crystal structure of Li2CuO2 has been investigated and its magnetic structure solved by neutron powder diffraction, and the magnetic moment of copper atoms at 1.5 K is 0.96(4)microB, which is very close to the saturation moment of spin only Cu+2 (d9).
108 citations