Indris, S.

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Li-Ionen-Dynamik in Kondensierter Materie: Vom Einkristall bis zu Li-Ionen-Batterien Sylvio Indris  Institute for Applied Materials – Energy Storage Systems Karlsruhe Institute of Technology Münster, June 4th, 2014 Experimental Techniques: Dynamics Structure Function NMR XRD Mössbauer QENS XAS EIS Materials Science, Energy Storage/Conversion, Geoscience     (Li-Ion Batteries, SOFC, Catalysis, …) Research Topics Li electrodes/electrolytes single crystals hydrous glasses catalysts fuel cell materials - water speciation - dynamics of water - TiO2, MoS2 - SOFC - PEM FC EFG,  NMR techniques - MAS NMR    (7Li, 6Li, 1H, 2H, 27Al, 29Si, 119Sn, …) - Single crystals - VT-NMR, lineshape analysis - 2D exchange NMR - Field-gradient NMR (SFG/PFG) - In situ NMR on complete battery cells - Relaxometry - -NMR MAS NMR spectroscopy   7Li, 6Li, ... - number of Li sites - identification of Li sites (comparison with reference materials) - exchange rates between sites (2D NMR) - mobilities of different Li species (temperature dependence) - direct measurement of diffusion coefficient (field gradients, ...) Ion Dynamics in Condensed Matter LiAlO2 Single Crystal space group P41212 a = 5.189 Å, c = 6.268 Å (isotopically pure 7Li) Reinhard Uecker, IKZ Berlin LiAlO2    Applications - Substrate for epitactic growth of III-V-type    Semiconductors (e.g. GaN)  - Fusion and Tritium Breeder Reactors - Coating in Electrodes for Li-Ion Batteries - Additive in Composite Polymer Electrolytes LiAlO2 :      B. Roling EA 1.2 eV Microscopic  and  Macroscopic  Diffusion Quantities Jump rate    l 2 6 t-1         f  = DT s           HR = DT Nq 2 kBT  Temperature dep. EA (depends on time window) Tracer diffusivity Conductivity Einstein-Smoluchowski Nernst-Einstein LiAlO2 :      Zeeman Splitting + Quadrupolar Shifts           7Li NMR wL = g · Bloc (e.g.: I = 3/2) Dm = 1 wgB0 -1/2 1/2 3/2 Zeeman splitting     quadrupolar shifts wQ ~ Q · Vzz m = -3/2 Q=(3z2-r2)rdV Vzz = 2 / z2 7Li  and 27Al NMR  on  LiAlO2 Single Crystal (001) (110) 7Li 27Al I = 3/2 I = 5/2 7Li NMR  on  LiAlO2 Single Crystal Electric field gradient tensor Vxx Vxy Vxz Vyx Vyy Vyz Vzx Vzy Vzz Vij = d2 / dxi dxj Vij = Vji               Vii = 0 Eigenvalues?   Eigenvektors? A B C B A -C C -C -2A 3-parameter fit of EFG tensor Indris et al., Phys. Rev. B 74 (2006), 245120. 7Li NMR on  LiAlO2  (110) 8·103 s-1 3·104 s-1 9·104 s-1 2.7·105 s-1 1.5·106 s-1 Indris et al., J. Phys. Chem. C 116 (2013), 14243. 7Li  and NMR on  LiAlO2 :   Motional narrowing  Hopping rate of 8 kHz at about 650K,       EA  1.0 eV Indris et al., J. Phys. Chem. C 116 (2013), 14243. 7Li  and NMR on  LiAlO2 :   T1 relaxation time  (110) EA  0.7 eV      (from s : 1.2 eV      correlated motion) Indris et al., J. Phys. Chem. C 116 (2013), 14243. LiAlO2      Indris et al., J. Phys. Chem. C 116 (2013), 14243. Conclusion / Outlook: •different NMR techniques have been    applied to study Li diffusion in LiAlO2 over     about 7 decades for D, t-1  •  good agreement with sdc Li ion batteries:  high energy density smaller devices Tarascon et al., Nature 414 (2001), 359 Li ion batteries: principle (here: discharging) anode negative electrode (graphite, carbons) cathode positive electrode (LiCoO2, LiMn2O4, LiNiO2) electrolyte separator current collector LiC6  Li+ + e- + 6 C  2 Li0.5CoO2 + Li+ + e-  2 LiCoO2  2 Li0.5CoO2 + LiC6  2 LiCoO2 + 6 C ΔRGӨ = -U0 ∙ n ∙ F Overview: Electrode materials  anodes Li4Ti5O12         TiO2 SnO2, (Ti/Sn)O2, (Al/Sn)O2, (Mg/Al/Sn)O2 …  ZnO MnFe2O4 , MgFe2O4  , … Y2Ti2O5S2  , …        cathodes  Li(Co/Ni/Mn/Al)O2  0.5 Li per TM 140 mAh/g   Li(Ni/Mn)2O4  0.5 Li per TM 150 mAh/g    Li(Fe/Mn/Co)PO4  1 Li per TM  170 mAh/g    Li2(Fe/Mn)SiO4  2 Li per TM ? 330 mAh/g ?    Li2(Fe/Mn)TiO4  , … 2 Li per TM ? 290 mAh/g ?    Synthesis Synthesis of Nanoparticles, Nanostructures and Nanocomposites:  - coprecipitation methods - sol-gel synthesis - hydrothermal/ solvothermal synthesis - solid-state reaction - electrospinning  → electrode film preparation Overview: Experimental Methods Standard sample characterization long-range structure, morphology XRD, SEM, TEM, …  Battery tests     cell performance      Solid State NMR spectroscopy  local structure (element-specific), (MAS, VT, PFG, in situ, relaxometry) dynamics  Fe + Sn Mössbauer spectroscopy short-range structure, (ex situ, in situ)    oxidation states  In situ XRD measurements  long-range structure   In situ XAS measurements  local structure (element-specific),      oxidation states  Impedance Spectroscopy  interfaces, degradation  In situ SEM    morphology  Mössbauer spectroscopy changes of local structure and charge state of Fe or Sn during reduction and oxidation Zn2SnO4 LiFe0.4Mn0.6PO4 Sn0 Sn4+ discharge discharge charge LixSn charge In situ SEM SnO2 • Particles grow and develop surface layers. • Mass contrast detected by backscattered electrons shows that coating has lower Z than SnO2 particle; consistent with the assumption that Li2O forms at surface of particles. CuCr2Se4 • Particles grow and break apart • formation of Cu metal whiskers  Cu-Li exchange mechanism (together with R. Mönig, KIT-IAM) D. Chen et al., J. Power Sources 196, 6382 (2011).  W. Bensch et al., Phys. Chem. Chem. Phys. 14, 7509 (2012).  LiCoO2:   NMR at different charge states/cycle numbers XRD 7Li MAS NMR long-range structure local structure N. Schweikert et al., Solid State Ionics 226 (2012), 15. LiCoO2 (R3m) Co(3+):   3d6 Co(4+):   3d5 In situ NMR Spectroscopy - in situ observation of changes   in local structure around   specific probe nuclei - elucidation of reaction mechanisms - observation of side reactions 7Li NMR spectrum of complete Li battery Li          Li4Ti5O12 N. Schweikert et al., J. Power Sources 228 (2013), 237. Ex situ 7Li MAS NMR Spectroscopy:  Li4+xTi5O12     (x = 0 … 3) Rearrangement of Li ions: Li+     Li(16c) Li(8a)     Li(16c) H. Hain et al., Solid-State Nucl. Magn. Reson. 42 (2012), 9. Ex situ NMR Spectroscopy:       Li4+xTi5O12 spin dynamics  Li ion dynamics - maximum: jump rate ≈ 104 s-1 - flank: activation barrier ≈ 0.3 eV relaxation rates equilibrium in B>0 distortion relaxation maximum:   wL  t-1 H. Hain et al., Solid-State Nucl. Magn. Reson. 42 (2012), 9. LiFePO4   LiCoPO4 : charge LiCoPO4 :     in situ XRD LiCoPO4 LiCoPO4 CoPO4 Li0.7CoPO4 Li0.7CoPO4 2-step mechanism + intermediate phase (≠ Fe) LiCoPO4 :  2 step reaction intermediate phase: Li0.7CoPO4 2 Li environments (1:1)     2 P environments (2:1) 2/3      3/4 LiCoPO4 view along c axis Co2+ Co2+ Co2+ Co2+ Co2+ Co2+ Li2/3CoPO4 view along c axis Co2+ Co2+ Co3+ Co3+ Co2+ Co2+ CoPO4 view along c axis Co3+ Co3+ Co3+ Co3+ Co3+ Co3+ LiCoPO4 :  LiCoPO4 :     in situ XAS on Co K edge highly reversible oxidation/reduction of Co2+/3+ Li2Fe1-yMnySiO4 / C - sol-gel synthesis  - nanocrystalline powders with carbon coating  - high capacity + high voltage possible (2 Li+ per TM ?)  high energy density  - flexible silicate network  - different polymorphs, isolation possible  R. Chen et al., J. Phys. Chem. C 117 (2013), 884. Li2Fe1-yMnySiO4 / C R. Chen et al., J. Phys. Chem. C 117 (2013), 884. y = 0.5 y = 0.2 y = 0 y = 1 Li2Fe1-yMnySiO4 / C R. Chen et al., J. Phys. Chem. C 117 (2013), 884. y = 0.2 y = 0.2 y = 0 Raman XRD P21/n P21/n, Pmn21, Pmnb P21/n, Pmn21 P21/n, Pmnb Li2Fe1-yMnySiO4 7Li MAS NMR y = 0.5 y = 0.2 y = 0 y = 1 Fe2+ , Mn2+   Fe3+ , Mn3+ R. Chen et al., J. Phys. Chem. C 117 (2013), 884. P21/n P21/n Pmn21 Pmnb P21/n Pmn21 P21/n Pmnb  * * Li2Fe1-yMnySiO4  Fe Mössbauer spectroscopy y = 0.2 y = 0 Fe2+   Fe3+ R. Chen et al., J. Phys. Chem. C 117 (2013), 884. discharge charge discharge charge Li2Fe1-yMnySiO4  in situ XAS y = 0.5 y = 0 Fe K edge Fe K edge Mn K edge R. Chen et al., J. Phys. Chem. C 117 (2013), 884. Ionic liquids as electrolytes  cycling with NMC + Li (together with M. Schulz, KIT-IAM) Electrolytes: Diffusion coefficients  →  Field Gradient NMR z B B = B0 + ΔB ∙ z ω = γ ∙ B (together with M. Schulz, KIT) Conclusions  observation of reaction mechanisms    at components and interfaces during Li insertion/removal  measurement of Li ion mobility:   t-1,  EA,  D  understanding function and degradation of materials/cells  LiCoPO4 :  ● reversible phase transformation with intermediate phase       LiCoPO4    Li2/3CoPO4    CoPO4    ● two-step mechanism, both steps: two-phase reaction     ● highly reversible oxidation/reduction  Co2+    Co3+          Li2(Fe/Mn)SiO4 :  ● Fe: single polymorph, Fe/Mn: mixture of polymorphs    ● highly reversible oxidation/reduction   Fe2+    Fe3+              Mn2+    Mn3+     ● high degree of structural disorder after cycling  Outlook  Li-Ion Batteries, SOFC, PEM, …  Method Development: - high temperature    - tomography    - electrophoretic NMR  NMR center:  structure/dynamics/methods  Theory/Modelling: Ion dynamics    electronic structures    spin density  MEET:   electrodes/electrolytes for Li-ion batteries Thanks Marco Scheuermann Ruiyong Chen Maximilian Kaus Krystyna Bachtin Christof Dräger    Ralf Heinzmann Ibrahim Issac Holger Hain Nina Schweikert Sebastian Becker Linda Wünsche 

Li-Ionen-Dynamik in kondensierter Materie: Vom Einkristall bis zu Li-Ionen-Batterien

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Li-Ionen-Dynamik in kondensierter Materie: Vom Einkristall bis zu Li-Ionen-Batterien

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