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NEW SOLID ELECTRLYTES BASED ON HYDROXIDES: FUNDAMENTAL and APPLIED ASPECTS

NEW SOLID ELECTRLYTES BASED ON HYDROXIDES: FUNDAMENTAL and APPLIED ASPECTS. Mother institute of 5 Nobelists. “ANCIENT HYSTORY” Origin of the interest in PROTON and LITHIUM properties in Hydroxides

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NEW SOLID ELECTRLYTES BASED ON HYDROXIDES: FUNDAMENTAL and APPLIED ASPECTS

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  1. NEW SOLID ELECTRLYTES BASED ON HYDROXIDES: FUNDAMENTALand APPLIED ASPECTS

  2. Mother institute of 5 Nobelists

  3. “ANCIENT HYSTORY” • Origin of the interest in PROTON and LITHIUM properties in Hydroxides • (applied and basic) • a) electrochemically directed: proton transport • S.Stotz, C.Wagner, Die Loeslichkeit von Wasserdampf und Wasserstoff in festen Oxiden, Ber.Bunsenges.Phys.Chem.70 (6) (1966) 781 • P.M.S. Stephen, A.T. Howe, Proton conductivity and phase relatuionships in solid KOH between 248 and 406C Solid State Ionics 1 (1980) 461. • Yu.M. Baikov, Electrical conductivity of solid KOH and NaOH, • Sov.Electrochem. 18 (1982) 1256. • K.-H. Haas, U. Schindewolf, The electrical conductivity of solid and molten cesium hydroxide – A contribution to Solid Proton Condutors • Ber.Bunsenges. Phys.Chem 87 (1983) 346 • K.-H. Haas, U. Schindewolf, The electrical Condutivity of Solid Alkali Hydroxides J.Sol,State Chem. 54 (1985) 342. • B.Sh. Elkin, Е.К. Shalkova, Yu.M. Baikov, Diffusivity of proton and electrical conductance of NaOH and KOH solid • Inorgan. Mater.23 (1) (1987) 81. • . b) physico-chemically directed: chemical state of proton and its effect on thermodynamical and kinetic properties of hydroxides • Yu.M. Baikov Isotopic equilibrium in a gas-crystal system near the phase-transition points Sov.Phys.JETP 51 (6) (1980) 1136. • Yu.M. Baikov, E.K. Shalkova, Isotopic Exchange Dihydrogen-Alkaline Solid Hydroxides Kinetics and Catalysiss, 21 (6) (1980) 1426 • D.T. Amm, S.L. Segel, Antiferroelectric properties of alkaline hydroxides Thermochimica Acta.95 (1985) 447. • T.J. Bastow, M.M. Elcombe, C.J. Howard, PMR Study of Hydroxide ions Solid State Comm.59 (5) (1986) 257 • c)Lithium vjbility • V.B.Ptashnik, Y.M. BaikovSelfdiffusion Li and H in solid LiOHSov.Phys.Solids 16, 3, (1974) 961 • D.M.Folstaedt, R.N.Bifeld NMR study of Li ionmotion in LiAlO and LiOH Phys.Rev.B. 16, 11 (1978) 5928

  4. Middle history 1990th • On the boundary between XX and XXI centuries1990 – 2005 • B.Sh. El’kin,Solid NaOH and KOH as superionic proton conductors: conductivity and its isotope effect, Solid State Ionics 37 (1990) 139. • M. Spaeth, K.D. Kreuer, Th. Dippel, J. Maier,Proton Transport Phenomena in pure alkaline metal Hydroxides, • Solid State Ionics 97 (1997) 291. • Yu.M.Baikov,The chemical state and the mobility of hydrogen in oxide-hydroxide solids, • Solid State Ionics 97 (1997) 471

  5. OUR MODERN • From 2005 up to now • Yu.M. Baikov, E.I. Nikulin, V.M.Egorov, A new ionic heterostructure of the palladium-solid hydroxide proton conductor type and its electrical characteristics in the region of the phase transition in electrolyte • Tech. Phys. Lett. 32 (3) (2006)220-222. • Yu.M.Baikov, Quantum isotope effect in “hydrogen solution in palladium-hydroxide proton conductor” • Tech. Phys. Lett. 32 (10) (2006) 850-853. • Yu.M. Baikov, Isotopic shift of the prrotonic heterojunction in novel palladium-hydroxide-proton-conductor heterotructures • Solid State Ionics 178 (2007) 487. • Yu.M.Baikov, V.M.Egorov, Self-Organized Microgeterogenety and High Proton Conductivity of a Solid Eutectic of Potassium and Sodium Hydroxides, • Tech. Phys. Lett 34 (6) (2008) 503 • Yu.M. BaikovNew heterostructures „hydrogenated metal-solid hydroxide proton conductor“ Tech.Phys. 53, 276 (2008)

  6. 2009 • Solid-Hydroxide Protonic Conductors: Superionic Conductivity, Phase Transition, Isotope Effect, and Self-Organized Microheterogeneity Yu.M.Baikov, V. M.Egorov Physics of the Solid State 2009 51, 1, 33-43 Proton Transfer in Electrochemically Active “Solid-Hydroxide Proton Conductor – Hydrogeneted Metal” Heterostructures Yu.M.Baikov Russian Journal of Electrochemistry 2009 45, 4, 364-373 • New Electrochemical Cells with Membrane-Electrode-Assembly generating Protonic Heterojunctions "Inorganic Proton Conductor-Hydrogenated Metal" Yu. Baikov J. of Power Sources 193, (2009) 371-375

  7. Compounds under study • Chemical Compounds (SOLIDS!!!!!) • KOH.H2O (146oC) NaOH.H2O (62oC) • KOH.2H2O (~ 38 – 40 oC) • Eutectics (SOLIDS!!!!!) • KOH.H2O+KOH (sometimes Commercial) • KOH+NaOH

  8. N E W SUPER P R O T O N I C S

  9. Isotopic effect of protonic conductivity measured by Direct Current on the same sample (!!!!) 1- at% D grows 2- at% D drops insert: blank experiment

  10. Superprotonic conduction and the significance of the self-organized microheterogeneity of the eutectics • Identification of the monohydrate KOHH2O and eutectics (KOH+KOHH2O) or (KOH+NaOH) with superprotonics is a point that does not appear to raise any question if we consider their macroscopic parameters (σ > 1 mS/cm, Eact ≤ eV). Viewed from the standpoint of the microscopic mechanism of conduction, however, the monohydrate and the eutectics should be treated separately. • Monohydrate samples are single phase although polycrystalline in texture. • Eutectics in the solid state are essentially heterogeneous mixtures of microcrystals of two chemically different compounds.

  11. Important part of PHASE DIAGRAM of KOH – H2O systemEutectic mixture of KOH+KOHH2O (~1:1) Chemical compoundmonohydrate KOHH2O .......................... Color peaks are the DSC spectra of studied compounds: 1. Monohydrate has melting point 419 K only! 2. Eutectic has melting at 373 K and at 360 K likely phase transition

  12. Comparison of the conductivity of solid eutectic KOH+KOHH2O as solid protonics (>84C) and individual components forming this eutectic at the same temperature range KOH below 150C are semiconductors!

  13. PHASE DIAGRAM of the system KOH+NaOH with EUTECTIC point at mole relation KOH:NaOH=1:1 Stars – phase transition points of individual compounds and “phase transition” of eutectic Orange columns indicate the temperature interval of superprotonic conductance of KOH, NaOH and their eutectic mixture. Peaks were obtained by Differential Scanning Calorimetry (DSC): Green – melting point; Blue – “phase transition”, likely 1st order transition.

  14. Comparison of the conductivity of solid eutectic KOH+NaOH as solid protonics (>84C) and individual components forming this eutectic at the same temperature range NaOH and KOH below 150C are semiconductors!

  15. The universally accepted concepts of physical chemistry concerning the micro- or nanosized heterogeneity characteristic of eutectic mixtures and on its sometimes dramatic effect on the physico-chemical properties underlie also two versions of the hypothesis bearing on the origin of conductivity of the eutectic (KOH+NaOH), which appears to be radically different in nature and substantially higher than that of individualNaOH and KOH. • The first version rests on the increase of the ionic conductivity of electrolyte-containing composite materials achieved by artificially making the material microheterogeneous, a phenomenon that has become a subject of intense interest. • The second version draws from the possibility of considerably modifying the properties of NaOH and KOH micro- or nanoclusters through self-organization of eutectics.This may become manifest, in particular, in a lowering of the temperatures of solid-state phase transitions, above which high protonic conductivity is known to exist. Deciding between these versions or selection of any other would require a dedicated study.

  16. Electrochemical activity of eutectic solid protonic conductor KOH+NaOH 1- Voltage on Cell 2- Potential of Protonic Heterojunction PdHx|OH- vs Pd 3. Power produced by this rechargeable battery after e.g. 24-hours charging by 0.4 mA at 1.7 V. Discharging by black arrow was stable ~15 hour.

  17. (-)Ti|KOHH2O|C Electrochemical activity of Ti(Hx)|KOHH2O|C, 370 K Monohydrate of KOH has proved as solid electrolyte of some electrochemical cells. (-)Ti|KOH.H2O|C(+) works as battery of e.m.f. 1.3-1.4 V Response of this cell on different type of loading (sign and value of overpotential ). Insert: details of peak of Z//

  18. Isotopic effect of the conductivity & electrode processes with KOHH2O (solid, Tm=419 K) measured by IMPEDANCE (Alternative Current) at 369 K (96 C) Really it was used three-electrode cell PdHx|KOHH2O|C, third electrode was Pd wire in the middle of electrolyte

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