Battery Design Flashcards
Zinc battery reaction
Do not contain high volumes of liquid Anode Zn(s)→Zn+2(aq)+2e- Cathode 2MnO2(s)+2NH4+(aq)+2e-→Mn2O3(s)+2NH3(g)+H2O(l)
Battery types
Lead-Acid Dry-cell (Alkaline and Zinc) Nickel-Cadium (NiCad) Nickel-Metal Hydride (NiMH) Lithium Ion
Alkaline Batteries
Slightly different reaction from standard zinc batteries Anode Zn(s)+2OH-(aq)→Zn(OH)2(s)+2e- Cathode 2MnO2(s)+2H2O(l)+2e-→Mn2O3(s)+2OH-(aq)
Overall Reaction Zn(s)+2MnO2(s)+2H2O(l)→Zn(OH)2(s)+2MnO(OH)(s)
Electrochemical Cell
A device that stages redox reaction that either results in or is driven by an electric current
Voltaic Cell
The half-cell battery component that produces the electric current from its spontaneous chemical reaction
Electrolytic Cell
The half-cell battery component that consumes current to drive its non-spontaneous chemical reaction
Half-cell
The first of two reactions in an electrochemical cell
Electrodes
Conductive surfaces through which electrons can either enter or leave the half sells
Electric Potential Difference
The difference in potential energy per unit of charge
Drives the electric current
Given in Voltage (V)
Cell potential (E.cell)
The total voltage between the two half-cells,
Depends on the relative tendencies of the reactants to undergo oxidation or reduction
Standard cell potential
Cell potential (E.cell) for 1M concentration of reactants and products in a chemical equation
Anode
The voltaic half-cell in which oxidation occurs from a spontaneous reaction
Gives an electron in products
Denoted (-) on the battery surface
Cathode
The electrolytic Half-cell that undergoes reduction
Consumes an electron to drive the non-spontaneous reaction
Denoted (+) on the battery surface
Standard electrode potential
The potential of an individual electrode in a halfcell
‘Salt bridge’
The battery component that supplies both the anode and the cathode with electrolytes to help fuel the reaction
Standard Hydrogen Electrode
The half-cell electrode that is normally chosen to have a potential of zero
Determining current direction
From the anode to the cathode, always
Determine which reaction undergoes oxidation, thats the anode, where the current is produced
Faradays constant
96,485
Electrolysis
The process through which an electric current passes through the cathode to drive its non-spontaneous reaction
Dry Cell Batteries
Batteries in which neither the anode nor the cathode contains high volumes of liquid reactants
Lithium ion battery mechanism of action
Lithium ions naturally travel from graphite to a (transition metal)-oxide, forming Lithium (transition metal)-oxide and producing a charge
The recharge uses an electric current to strip the lithium ions from the cathode
Nickel metal-Hydride reaction mechanism
Anode M,H(s)+OH-(aq)→M,(s)+H2O(l)+e-
Where ‘M,’ indicates a metal alloy
Cathode NiO(OH)(s)+H2O(l)+e-→Ni(OH)2(s)+OH-(aq)
Nickel-cadmium battery mechanism of action
Anode Cd(s)+2OH-(aq)→Cd(OH)2(s)+2e- Cathode 2NiO(OH)(s)+2H2O(l)+2e-→2Ni(OH)2(s)+2OH-(aq)
Hydrogen Fuel Cell
Hydrogen gas and a hydroxide solution are supplied to the cell and react, producing water and giving off 4 electrons. These electrons run up the anode, are supplied to the electrical circuit, and re-enter the fuel cell through the cathode where they drive the reaction between oxygen gas and water producing 4OH- ions
