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
Alcohol based Batteries
Ethyl-alcohol (CH3CH2OH) gas reacts with a OH- solution in the anode,producing acetic acid gas (HC2H3O2), liquid water, and giving off 4 electrons which run through the circuit and back to the cathode to drive the reaction between oxygen gas and the water to re-form the OH- solution
Galvanic corrosion
A type of corrosion that occurs when two metals are in electrical contact with one another
Factors in galvanic corrosion
Humidity, anode to cathode surface area ratio, metal types, temperature, salinity
Galvanic Serries
An ordered list of materials that describe (from noble to active) metals that resist galvanic corrosion
Betavoltaic cells
Uses a beta-radiation to supply electrons to a system and an electrolytic cell as a cathode
Reciprocating electromechanical atomic batteries
Battery builds up a difference in charge between two plates, as one approaches the other, they make contact and redistribute their charge, pushing each other appart, putting pressure on a piezoelectric material
Optoelectric nuclear battery
The beta-nucleide emits beta particles that stimulate a excimer mixture, used as a photovoltaic cell
Alpha-voltaic batteries
Use alpha-particles (He-4) to produce electrons from semi-conductors
Proper battery casing
Plastic tube housing externally covered with a layer of aluminum
Proper battery storage
Give initial charge before storing
Side by side, never with the ends touching,
At low temperatures to preserve electric potential recovery
Keep dry at all costs
Factors in designing custom batteries
1) Battery life
2) Density (Weight to Volume)
3) Voltage demands
4) ‘Green’ friendly factors
5) Corrosive properties of the operating environment
6) Thermal requirements
Homemade Battery from Soda
1) Pour soda in plastic cup
2) Insert a tall piece of aluminum in soda and clip to cup edge
3) Insert a tall piece of copper in soda and clip to cup edge
4) Test electrodes with the voltmeter (or circuit)
Homemade Battery from Saltwater
1) Pour water in plastic cup
2) Mix tablespoon of salt
3) Clip aluminum strip to the edge
4) Clip zinc strip to the edge
5) test with a voltmeter or circuit
Homemade battery from high molarity bleach solution
1) Pour water in plastic cup
2) Mix bleach
3) Clip copper strip to the edge
4) Clip aluminum strip to the edge
5) test with a voltmeter or circuit
Homemade lemon battery
1) Prep the lemon by squeezing the inside without breaking the peel at all
2) Insert copper into lemon
3) Insert Steel into lemon
4) Wire up a few more, connecting ones steel to the other’s copper
5) test with voltmeter or curciut
‘Green’ factors in batteries
Galvanic corrosion products, Nuclear Penetrating power, Rechargeable, Digestion effects, Fracture Exposure effects, Production energy, Supply sources
Battery Gibbs free energy
ΔG=-nFE.cell
F=faradays constant
n=moles
Battery Equilibrium constant from voltage
log(K)=E.cell/(0.0592/n)
Voltage from battery equilibrium
E.cell=(0.0592/n)*log(K)
