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Recent advantages in low temperature proton exchange membrane fuel cells in Russia: materials development and application features March 31, 2015 Andrey Yaroslavtsev Kurnakov Institute of General & Inorganic Chemistry RAS, Moscow
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2 Technologies of the future will be based on the clean and safe energy sources
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Scheme of pore and channel structure in ion exchange membranes W.Y. Hsu, T. D. J. Gierke. Membr. Sci. 1983. 13. 307 3
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1.High moisture is necessary (90-100 %), 2.Limited temperature range (up to 90-100 о С), 3.Catalyst poisoning by CO (all cheap H 2 forms contains CO admixture). C n H 2n+2 + nH 2 O nCO + (2n+1)H 2 C n H 2n+2 + 2nH 2 O nCO 2 + (3n+1)H 2 C n H 2n+2 + n/2 O 2 nCO + (n+1)H 2 C n H 2n+2 + nO 2 nCO 2 + (n+1)H 2 C + H 2 O CO + H 2 Disadvantages of Nafion membranes for fuel cell: 4
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walls sorb precursor for nanoparticle synthesis (ions, complexes,..), they limit the reaction volume (size of particles), walls of the membrane pore isolate particles from each other and reduce the surface tension, providing their thermodynamic stability. Nanopores of membranes present the nanoreactors for the nanoparticle synthesis: Yaroslavtsev A.B./ Rus.Nanotechnologies. 2012, V.7,N9-10. p. 8-18. 5
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Membrane modification procedures In situ + small size of nanoparticles (2- 5 nm) + homogeneous distribution -impossibility of membrane synthesis with given dopant concentration TEM microghaphs of Nafion + SiO 2 /Cs x H (3-x) PW 12 O 40, obtained via in situ method. 6 TEM microghaphs of similar membrane obtained by casting.
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Temperature dependence of conductivity in contact with water for Nafion 212 membrane (1) and Nafion 212 + 1 wt.% SiO 2 + 1.9wt.% Cs x H 3-x PW 12 O 40 (2) 7
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Scheme of the pores and channels system in the hydrated MF-4SC membrane. Scheme of the pores and channels system in MF-4SC membranes doped by nanoparticles. Novikova S.A., Safronova E.Yu, Lysova A.A., Yaroslavtsev A.B. Influence of incorporated nanoparticles on ion conductivity of MF-4SC membrane // Mendeleev Commun., 2010, V.20, N3 P.156-157. 8
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Proton conductivity. Low relative humidity The lower the humidity, the more is the gain in the hybrid membranes conductivity in comparison with the initial Nafion membranes. Conductivity of hybrid membranes is less dependent on humidity as compared with the initial membrane. 9 The conductivity dependence on the relative humidity for Nafion 212 and hybrid membrane
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Current-voltage characteristics of the MEA with membrane Nafion-112 modified by 1%SiO 2 +1.9% Cs x H 3 ‑ x PW 12 O 40 10 Power of the MEA with hybrid membranes for different humidity of gases Use of hybrid membranes in Fuel cells
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The dependence of the maximum power of the MEA with Nafion 212 and Nafion 212 + 1 wt.%SiO 2 +1.9wt.%Cs x H 3-x PW 12 O 40 membranes of the incoming gas moisture Maximum power of the MEB 11 HM have its own catalytic effect in the reaction of the electrocatalytic oxygen reduction (exchange current)
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Cathode and anode materials for lithium-ion batteries Li[Li 1/3 Ti 5/3 ]O 4 + 3е – + 3Li + = Li 2 [Li 1/3 Ti 5/3 ]O 4 Theoretical capacity: 175 mAh/g LiFePO 4 LiFePO 4 - е – = FePO 4 + Li + Theoretical capacity: 170 mAh/g Li[Li 1/3 Ti 5/3 ]O 4 12 Advantages: Environment friendly and safety Good cyclability and reversibility Small changes in cell parameters Stable voltage for charge and discharge Disadvantages: Low electronic and ionic conductivity
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SEM of Li 4 Ti 5 O 12 (1023 K - a) and TEM micrographs (b) and electron diffraction (c) for nanocomposite Li 4 Ti 5 O 12 /TiO 2 673 K. a 13 b
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The cycling performance of lithium titanate calcined at 1073 (a) and 673 K (b) at different current densities 14 cycle number Q, mAh / g
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15 CompositionE charge, VE dischar, VE ch - E disch, V LiFePO 4 /C3.53.340.16 LiFe 0.9 Co 0.1 PO 4 /C3.483.400.08 LiFe 0.9 Ni 0.1 PO 4 /C3.463.420.04 The charge and discharge potentials for LiFe 1-x M II x PO 4 (M II =Co, Ni, Mg) Li/Li +. Energy losses in the course of charge / discharge cycles are reduced by 40 - 70% The dependence of the discharge capacity on the cycle number at different current densities for LiFe 0.9 Ni 0.1 PO 4 samples. The values of current density (mA /g) are shown in Fig. Q, mAh/g Cycle number
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List of suggestions 1.Hybrid membranes for fuel cells (increased conductivity, ability to operate at low humidity) 2.The hybrid membranes for water purification (electrodialysis) 3.Multisensory systems based on the hybrid membrane 4.The development of energy storage using hydrogen cycle 5.Cathode nanomaterials based on lithium ferrophosphate 6.Anode nanomaterials based on lithium titanate
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