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DFG Priority Programme SPP 1473, WeNDeLIB :

DFG Priority Programme SPP 1473, WeNDeLIB : Thermodynamics and Kinetics for Stabilization of Conversion-Type Electrodes for LIB Based on Nano 3d Transition Metal Oxides. Thermodynamic Description of the Li-Cu-O System for Conversion Type Electrode Materials for Lithium Ion Batteries.

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DFG Priority Programme SPP 1473, WeNDeLIB :

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  1. DFG Priority Programme SPP 1473, WeNDeLIB: Thermodynamics and Kinetics for Stabilization of Conversion-Type Electrodes for LIB Based on Nano 3d Transition Metal Oxides Thermodynamic Description of the Li-Cu-O System for Conversion Type Electrode Materials for Lithium Ion Batteries M. Lepple, D.M. Cupid, P. Franke, C. Ziebert, H.J. Seifert

  2. ElectrochemicalConversionMechanism • Electrochemicalconversionmechanism • X = O, N, F, S, P • More than 1 Faraday charge per molecanbetransferred • High theoreticalcapacity • Conversionmechanismdoes not need a stablecrystallographicstructurefreedom in material selection • Bad cyclingstability J. Cabana, et al. Adv. Mater.22, E170-E192 (2010). MSE Congress 2012 Maren Lepple

  3. Material System: Li-Cu-Fe-O • Fe-oxides • High theoretical capacity • Cu-oxides • Cycling stability • Mixedtransitionmetalcompounds • Show an overallperformancesimilarto simple oxides • Potentialisdominatedbymetalcontent adjustment of batteryperformance Theoretical capacity: CuFe2O4: 896 mAh g-1 Theoretical capacity: CuO: 674 mAh g-1 Cu2O: 375 mAh g-1 Theoretical capacity: Fe2O3: 1007 mAh g-1 Fe3O4: 926 mAh g-1 MSE Congress 2012 Maren Lepple

  4. Motivation forThermodynamicDescriptions • Overall drivingforceacross a electrochemicalcellisdeterminedbythechange in thestandard Gibbs freeenergy • Thermodynamiccalculationsbased on the CALPHAD method (Coupling of thermochemistry and phasediagram) • Predictbatteryperformance (OCV, capacity) • Database developmentforthe Li-Cu-Fe-O System: • The Cu-Fe-O ternarysystemassessed byKhvan et al., Journal of Phase Equilibria and Diffusion, 2011, 32:498-511 • First calculatedphasediagrams in the Li-Cu-O systemaddressed in presentwork MSE Congress 2012 Maren Lepple

  5. Li-Cu-O System at 298.15 K 298.15 K Investigatedbycoulometrictitration N.A. Godshall, Solid State Ionics 1986, 18&19:788-793 MSE Congress 2012 Maren Lepple

  6. Li-Cu-O System at 298.15 K 298.15 K Is the LiCu2O2phasestable? S. Patat et al., Solid State Ionics 1991, 46:325-329 MSE Congress 2012 Maren Lepple

  7. Database Developement Li-Cu-O System Li-O: K. Chang, B. Hallstedt, CALPHAD, 2011, 35:160-164 Cu-O: B. Hallstedt, L.J. Gauckler CALPHAD, 2003, 27:177-191 Li-Cu: N. Saunders, I. Ansara (Ed), Cost 507 Report,1994,168–169 Extrapolation frombinaryassessments MSE Congress 2012 Maren Lepple

  8. Database Development Li-Cu-O System Formation based on thecompounds in thethree-phasefield All phases in thethree-phase equilibriumareconsideredas pure substances LiCuO: 298.15 K Li2CuO2: MSE Congress 2012 Maren Lepple

  9. Database Development Li-Cu-O System 298.15 K Ternarycompoundsincluded MSE Congress 2012 Maren Lepple

  10. Titration Curves • Equilibrium cellvoltageas a function of lithiumcontentatthecathodealongselectedcompositionpaths MSE Congress 2012 Maren Lepple

  11. Description ofTemperatureDependence • Stoichiometricphase (AB) • a, csolutioncalorimetry, cpmeasurements • b,clow T cpmeasurements (0 – 298.15 K), ab initio • ccpmeasurements • Phase stability • DTA/TGA GHSERA: Gibbs freeenergyofcomponent A withreferencetothestandardenthalpyoftheelementat 298.15 K a, b, c,…: Variables MSE Congress 2012 Maren Lepple

  12. Experimental Investigations • Sample preparation via solid statereaction • Li2CuO2 • LiCu2O2 • Sample characterization • XRD • Thermal analysis • Specificheatcapacitywith DSC • Phase stabilityof LiCu2O2 in argonandairwithsimultaneous DTA/TGA Includeresults in database XRD MSE Congress 2012 Maren Lepple

  13. HeatCapacity • Li2CuO2: • -10 – 400°C, HR=10 K/min • LiCu2O2: • -10 – 200°C, HR=10 K/min MSE Congress 2012 Maren Lepple

  14. Phase Stabilityof LiCu2O2 • Simultaneous DTA/TG (Setaram) • 200-900°C, HR=10 K/min, 3 cycles • In argon • Reversible phasetransformationat 705 °C • Slightmassloss due toreductionof Cu+2 Cu+1athightemperatures • In air • Irreversible phasetransformationaccompaniedwithmassgainΔTG during 1st cycle Maren Lepple MSE Congress 2012

  15. Phase Stabilityof LiCu2O2 • Simultaneous DTA/TG (Setaram) • 200-900°C, HR=10 K/min, 3 cycles • In argon • Reversible phasetransformationat 705 °C • Slightmassloss due toreductionof Cu+2 Cu+1athightemperatures • In air • Irreversible phasetransformationaccompaniedwithmassgainΔTG during 1st cycle • Reversible phasetransformations in 2nd and 3rd cycles Maren Lepple MSE Congress 2012

  16. Conclusionsand Outlook MSE Congress 2012 Maren Lepple

  17. Acknowledgment • This work is supported by the priority programme SPP 1473 WeNDeLIB of the German Science Foundation (DFG) in the project SE 647/14-1. • Thanksto Robert Adam (TU Freiberg) Thank you for your kind attention! MSE Congress 2012 Maren Lepple

  18. OCV vs. Experimental Results Potential plateauofCuOand Cu2O: ~1.4 V S.J. Hibble, Solid State Ionics 1990, 39:289-295 MSE Congress 2012 Maren Lepple

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