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Majdi IREC
- 1. 1 Authors : Majdi Lahsini, Yassine ben Belgacem, Chokri Khaldi, Jilani Lamloumi
- 2. Theoratical approches used • Theoretical approaches used to calculate kinetic and corrosion parameters : • the exchange current density of H2O/H2 system • The equilibrium potential for H2O/H2 system • the material degradation rate constant (2 slides) Metal hydride formation mecanismes • Hydrogen storage using solid-gaz method • Electrochemical hydration • Schematic diagram of a nickel-metal hydride battery (3 Slides) Introduction • An introduction to this work (4 slides) 2 1 3 2 Plan Results and discussions • The obtained results and disccussions (6 slides) 2
- 4. Energy consumption in the world is dominated by the fossil fuels energy. Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions Disadvantages of Fossil Fuels Non-renewable Depletion Negative effect on the environment and the human health, Accidents can be disastrous Greenhouse gas 4
- 5. 5 Solar powerWind power Hydraulic power Renewable Energies Geothermal power Problem in energy storage Natural and clean energies lasts a long time Poor performance in comparison to fossil energies High installation price We must develop new renewable energies Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions
- 6. It combustion generate a huge amount of energy (about 3 times greater than … Sa combustion génère une forte quantité d’énergie (environ 3 fois plus que l’essence à poids constant) • It’s the smallest chemical element wich make . • Hydrogen is the most abundant chemical substance • in the universe. 6 Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions
- 7. 7 Hydrogen Applications Aerospace Applications Stationary applications 2020 Olympic Games, the « Olympic town » in Tokyo Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions Honda Clarity (2017) Transport Applications
- 8. 8 Hydrogen Storage Liquid Compressed gas Solid Adsorption Carbon nanotubes Absorption Metal Hydrird Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions
- 10. 10 Metal Hydride Metal H2 Hydrogen storage using solige-gaz method Metal hydrides are metals which have been bonded to hydrogen to form a new compound. Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions
- 11. Electrochemical hydration is based on the direct contact of the alloy and the Potassium hydroxide solution. And it’s done by water reduction 11 H2O(s)Had OH- (s) Habs Electrode Electrode / electrolyte interface Electrochemical hydration KOH … Water reduction 𝐻 𝑎𝑑 ⇔ 𝐻 𝑎𝑏𝑠 𝑂𝐻𝑠 − ⇔ 𝑂𝐻𝑣 − Diffusion Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions
- 12. 12 Schematic diagram of a nickel-metal hydride battery During charge During discharge 𝒙𝑵𝒊 𝑶𝑯 𝟐 + 𝒙𝑶𝑯− ⇔ 𝒙𝑵𝒊𝑶𝑶𝑯 + 𝒙𝑯 𝟐 𝑶 + 𝒙𝒆− 1 𝑴 + 𝒙𝑯 𝟐 𝑶 + 𝒙𝒆− ⇔ 𝑴𝑯 𝒙 + 𝒙𝑶𝑯− 2 𝒙𝑵𝒊𝑶𝑶𝑯 + 𝒙𝑯 𝟐 𝑶 +⇔ 𝒙𝒆− 𝒙𝑵𝒊 𝑶𝑯 𝟐 + 𝒙𝑶𝑯− 1 𝑴𝑯 𝒙 + 𝒙𝑶𝑯− ⇔ 𝑴 + 𝒙𝑯 𝟐 𝑶 + 𝒙𝒆− 2 Final Equation 𝒙𝑵𝒊 𝑶𝑯 𝟐 + 𝑴 ⇔ 𝑴𝑯 𝒙 + 𝒙𝑵𝒊𝑶𝑶𝑯 Final Equation 𝑴𝑯 𝒙 + 𝒙𝑵𝒊𝑶𝑶𝑯 ⇔ 𝒙𝑵𝒊 𝑶𝑯 𝟐 + 𝑴 Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions
- 14. 14 𝐸(+𝑖) 𝐸(−𝑖) ∆𝐸(i) The equilibrium potential for H2O/H2 system 𝑬 𝑯 𝟐 𝑶 𝑯 𝟐 𝒆𝒒 = 𝑬(+𝒊) + 𝑬(−𝒊) − 𝒃 𝒍𝒐𝒈 𝒊 𝒄𝒉𝒂𝒓𝒈𝒆 𝒊 𝒅𝒊𝒔𝒄𝒉𝒂𝒓𝒈𝒆 𝟐 The exchange current density H2O/H2 system 𝑙𝑜𝑔 𝑖 𝐻2 𝑂/𝐻2 0 = 1 2 𝑙𝑜𝑔( 𝑖 𝑐ℎ𝑎𝑟𝑔𝑒 . 𝑖 𝑑𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒) − ∆𝐸 2𝑏 -1.20 0 5000 10000 15000 20000 -1.05 -0.90 -0.75 -0.60 Charge/dischargepotential (E/V.vsHgO) Time(s) Charge discharge tdischarge 𝐶 𝑚𝐴ℎ. 𝑔−1 = 𝑖 𝑚𝐴 . 𝑡 𝑑𝑖𝑠𝑐ℎ𝑎𝑟𝑔𝑒(ℎ) 𝑚(𝑔) Electrochemical discharge capacity Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions
- 15. 15 𝐶 = 𝐶0 exp(−𝑘 𝑑𝑒𝑔𝑟 𝑁) 𝑘 𝑑𝑒𝑔𝑟 : the material degradation rate constant (Cycle-1) 𝑘 𝑑𝑒𝑔𝑟 = −2,303 𝜕 log 𝐶 𝜕𝑁 Simulation (fit) 𝐶 = 𝐴0 exp −𝑘 𝑑𝑒𝑔𝑟 𝑁 + 𝑌0 𝑌0 Nombre de cycles Electrochemicaldischargecapacity 0 20 40 60 80 100 120 0 100 200 300 Experimental curve mAhg-1 Simulation curve 0 50 100 50 100 150 200 250 300 Electrochemicaldischargecapacity Capacité Nombre de cycles Experimental curve Simulation curve 𝑘 𝑑𝑒𝑔𝑟 = − 𝜕 ln( 𝐶 𝑌0 − 1) 𝜕𝑁 First case Second case Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions
- 17. 17 C/3 C/5 C/10 C/20 LaY2Ni9 0,770 0,130 0,060 0,018 Decrease of the potential jump with the decrease of the discharge rate Le saut du potentiel ΔE Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions The potential jump, ∆E(i), undergoes a gradual decrease before it becomes constant This decrease becomes more accentuated by going from a low to a strong regime.
- 18. 18 The potential jump variation with the discharge rate is linear. This variation decreases progressively with the increase of cycle numbers. Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions The discharge rate effect on the potential jump
- 19. 19 The equilibrium potential for H2O/H2 system C/3 C/5 C/10 C/20 LaY2Ni9 -1,121 -1,125 -1,113 -1,125 Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions During the first cycles, the evolution of the equilibrium potential towards its most positive values due to activation appears only for the C/20 regime.
- 20. 20 C/3 C/5 C/10 C/20 LaY2Ni9 25,8 21,8 18 16,2 The exchange current density for H2O/H2 system Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions Throughout the first cycles, the exchange current density increases progressively with electrochemical cycling regardless of the discharge rate. After activation, and beyond certain cycle number, the exchange current density becomes steady
- 21. 21 C/5 C/10 C/20 𝐴0 (𝑚𝐴ℎ. 𝑔−1 ) 110,61 136,67 106,173 𝑌0 (𝑚𝐴ℎ. 𝑔−1 ) 126,44 143,26 137,638 kdegr (cycle−1 ) 0,0397 0,0510 0,0360 𝐶 = 𝐴0 exp −𝑘 𝑑𝑒𝑔𝑟 𝑁 + 𝑌0Material degradation rate constant kdegr Introduction Metal hydride formation mecanismes Theoratical Approches Used Results and Discussions For the middle discharge rate C/10, LaY2Ni9 electrode is characterized by the highest material degradation rate constant
- 22. 22 Conclusions
- 23. 23 The purpose of the present paper is to study the kinetics and corrosion properties of LaY2Ni9 using galvanostatic charge/ discharge curves obtained by Yassine ben Belgacem. The following conclusions can be drawn up: • Potential jump decreases with the discharge rate. This decrease is a reflection of more significant electrode stability for the lower discharge rate. • The exchange current density for H2O/H2 system increases with the discharge rate reflecting faster reactions. • The discharge rate doesn't have a significant impact on the equilibrium potential.
- 24. 24 Thank you for your attention
Editor's Notes
- L'augmentation de leur concentration dans l'atmosphère terrestre est l'un des facteurs à l'origine du réchauffement climatique ce qui a un effet négative sur l’énvironnement, mais également sur la saanté humaine.
- problemes
- L’hydrogène est actuellement reconnu comme étant une solution prometteuse comme vecteur énergétique propre, renouvelable et hautement énergétique. En effet ..
- Le gouvernement espère voir des voitures et des bus, voire même la salle de presse ou encore les résidences des athlètes fonctionnant à l'hydrogène.
- Le gouvernement espère voir des voitures et des bus, voire même la salle de presse ou encore les résidences des athlètes fonctionnant à l'hydrogène.
- Cette figure présente exemple d’un cycle de charge décharge obtenue par l’application dun courant constant à l’électrode.
- A chaque cycle de charge de décharge
- Ces valeurs montrent bien que l’électrode à hydrure est plus stable pour les faibles régimes et cette stabilité est importante par substitution de lanthane par le cérium.