SPECIALITY OF MnO2More practicalInexpensive Pseudocapacitive MaterialExhibits theoretical specific capacitance of approximately 1,100 Fg through stochiometric reduction of MnO2 to MnOOH in a
BUT!!The capacitance for thick MnO2 film is ultimately limited by the poor electrical conductivity of MnO2The stability of EC in the thin MnO2 film configuration is restricted because of low mass
How To Overcome TheProblems? To overcome the electrical resistance of MnO2, Silver (Ag) was incorparate into MnO2 thin films. Why? Ag mass loading was accomplished using cathodic eletrodeposition which lead to higher specific capacitance
EXPERIMENTAL 1. CHEMICALS AND MATERIALS 2. ELECTRODEPOSITION3. STRUCTURAL AND MORPHOLOGICAL CHARACTERIZATION 4. ELECTROCHEMICAL EVALUATION
Ruthenium OxidesMaterialsAbout : High theoretical specific capacitance : 1358 F g-1 High electrical conductivity : 3Å~102 Ω-1 cm-1
Ruthenium Oxides Materials Amorphous hydrous RuO2 prepared by sol-gel methods with Specific capacitance of 720 F g-1 High capacitance is attributed to hydrous surface layers that enable facile transport of electrons and protons The capacitance decreased rapidly at higher rates due to proton depletion and over-
Ruthenium Oxides Materials A two-dimensionally controlled RuO2 nano-sheet was invented for better electronproton transportHow to improve the rateperformance? Small particles of hydrous RuO2 can combine with carbon materials, such as with activated
Ruthenium Oxides MaterialsFigure 1 : Proposed pseudocapacitor materials in the literature.
Ruthenium Oxides MaterialsConclusionECs based on RuO2 and other oxides including MnO2 and NiO arebetter configured in aqueous media and some of them are beinginvestigated for miniaturized devices because of their costeffectiveness.
SOLID ELECTROLYTE Composed of RbAg4I5 increase energy storage without causing dendrite growth serves as an ionic conductor for the ionic part of the current within solid - state cell Conductivity Range = 10-3 S/cm <σ< 10 S/cm Ions carry the current Conductivity decreases exponentially as temperature decreases
GENERAL CHARACTERISTICS : SOLIDELECTROLYTES1. A large number of the ions of one species should be mobile. This requires a large number of empty sites, either vacancies or accessible interstitial sites. Empty sites are needed for ions to move through the lattice.2. The empty and occupied sites should have similar potential energies with a low activation energy barrier for jumping between neighboring sites. High activation energy decreases carrier mobility, very stable sites (deep potential energy wells) lead to carrier localization.3. The structure should have solid framework, preferable 3D, permeated by open channels. The migrating ion lattice should be “molten”, so that a solid framework of the other ions is needed in order to prevent the entire material from melting.4. The framework ions (usually anions) should be highly polarizable. Such ions can deform to stabilize transition state geometries of the migrating ion through covalent interactions.
OTHER SOLID ELECTROLYTEMATERIALS NAFION ® Tetra methylammonium penta hydrate (also known as hydrated TMAH5 ) Li+ Ion Conductors LiCoO2, LiNiO2 LiMnO2 Lithium aluminium oxide (Li5AlO4) F- Ion Conductors PbF2 & AF2 (A = Ba, Sr, Ca)
SOLID ELECTROLYTE ADVANTAGES- Freedom from fluid leakage- Low ionic conductivities- Feasibility of small layer thickness- Can be deeply discharged many times
INTRODUCTION A battery containing a liquid solution of acid and water. Other names are flooded cell and wet cell battery 2 different types: i. primary battery-non rechargeable ii.secondary battery- rechargeable
An electrical storage device that uses a reversible chemical reaction to store energy. It uses a combination of lead plates or grids and an electrolyte consisting of a diluted sulphuric acid to convert electrical energy into potential chemical energy and back again.The electrolyte of lead-acid batteries is hazardous to our
DISCHARGE The discharge process is driven by the conduction of electrons from the negative plate back into the cell at the positive plate in the external circuit. Negative plate reaction: Pb(s) + HSO−4(aq) → PbSO4(s) + H+(aq) + 2-e Positive plate reaction: PbO2(s) + HSO−4(aq) + 3H+(aq) + 2-e → PbSO4(s) + 2H2O(l) The total reaction can be written: Pb(s) + PbO2(s) + 2H2SO4(aq) → 2PbSO4(s) + 2H2O(l)
Charging The charging process is driven by the forcible removal of electrons from the positive plate and the forcible introduction of them to the negative plate by the charging source. Negative plate reaction: PbSO4(s) + H+(aq) + 2-e → Pb(s) + HSO−4(aq) Positive plate reaction: PbSO4(s) + 2H2O(l) → PbO2(s) + HSO−4(aq) + 3H+(aq) + 2-e
ADVANTAGE Low cost. Reliable. Over 140 years of development. Robust. Tolerant to abuse. Tolerant to overcharging. Low internal impedance. Can deliver very high currents. Indefinite shelf life if stored without electrolyte. Can be left on trickle or float charge for prolonged periods. Wide range of sizes and capacities available.
DISADVANTAGESVery heavy and bulky.Danger of overheating during chargingNot suitable for fast charginglow energy densityCause environmental damage, which is environmentally
Ionic liquid Defined as salts consisting entirely of ions i) melting points lower than 100 C - ionic conductivity is very high. ii) very low vapor pressures - are not flammable, even if they consist of organic compounds. Two class of ionic liquid : i) aprotic or conventional ii) protic ionic liquids (PILs). - generally prepared by a neutralization reaction of an organic base like amine and an acid. - If both are strong enough, proton transfer from the acid to the base occurs.
Ionic liquid Electrolyte Most common cation classes of ionic liquids are i. Quaternary ammonium ii. Imidazolium, iii. Pyridinium iv. Phosphonium Physico-chemical properties i. Viscosity ii. solubility properties iii. density iv. acidity/basicity v. coordination properties vi. stereochemistry
Importance of ionic liquid Melt at ambient temperature Because ionic liquids are composed of only ions, they show very high ionic conductivity, non-volatility, and non- flammability. The non-flammability and non-volatility inherent in ion conductive liquids open new possibilities in other fields as well. multi-purpose materials, so there should
Viscosity physico – chemicalproperties Viscosity of Imidazolium-Based Ionic Liquids at Elevated Pressures : Cation and Anion Effects by Azita Ahosseini and Aaron M. Scurto Ionic liquid used : Imidazolium – based Common cation classes and anions used with ionic liquids.
Schematic diagram to test the viscosity using visc
(c) Modified TiO2 nanoparticles.(d) Diffusion of I3-through a matrix of (A) modified and (B) unmodified TiO2 nanoparticles.
Proposed process for the extraction of cesiumfrom aqueous tank waste using n-Bu3MeNNTf2- +BOBCalixC6.
Advantages of ionic liquid It is possible to “engineer” the physicochemical properties of RTILs by the choice of the ionic constituents. use of these liquids as electrolytes for Li batteries and low-temperature fuel cells. The non-volatile electrolyte solution will change the performance of electronic and ionic devices. will be composed of organic ions, and these organic compounds will have unlimited
Disadvantage of ionic liquid The benefits of replacing the volatile organic solvent component far outweigh this disadvantage. Low electrolytic conductivity Need of tight closure to isolate from atmospheric moisture High environmental impact High cost