Zinc Air Batteries By: Ana Brar - PowerPoint Presentation

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Zinc Air Batteries

By: Ana Brar

General Information

Activated when oxygen is absorbed into the electrolyte through a membraneUsually reaches full operating voltage within 5 seconds of being exposed to airOxygen diffused directly into batteryElectrolyte that catalytically promotes the reaction of oxygen, but is not depleted or transformed at discharge

Oxygen from air

Zinc and alkaline electrolyte

Button cell

Advantages

Weight - not necessary to carry a second reactantHigh energy densityCompetitive with Lithium-ion Inexpensive materialsFlat discharge voltageSafety - don't require volatile materials, so zinc-air batteries are not prone to catching fire like lithium-ion batteriesExcellent shelf life, with a self-discharge rate of only 2% per year Available in a range of button and coin cell sizesRechargeable high power fuel cells in the process of development Environmental benefitsHave high volumetric energy density compared to most primary batteries

Disadvantages

Sensitive to extreme temperature and humid conditionsCarbon dioxide from the air forms carbonate which reduces conductivityHigh self discharge (after seal is broken)After activation, chemicals tend to dry out and the batteries have to be used quicklyAlthough recharging is possible for fuel cells, it’s also inconvenient and is only suitable for high power typesZinc air batteries must be larger to satisfy high current needsHigh power batteries use mechanical charging in which discharged zinc cartridges are replaced by fresh zinc cartridges—therefore the used cartridges must be recycledHave flooding potentialLimited outputWhen zinc turns it into zinc oxide it expands, space

Common uses

Hearing AidsWatchesMobile phonesDigital CamerasPagersPower sources for electric fencesRecharging Li-Ion batteriesTransportation:Cars - EVsBuses

Rechargeability

Zn/Air Batteries – not rechargeable

Zn/Air Fuel Cells – rechargeable

ReVolt has developed rechargeable Zinc/Air batteries

In future: EVs using Zn/Air?

Zinc-air batteries can be made for high rate applications, which have a short life but high output

Or low rate, with low power but last a longer amount of time

Transportation

Would use Zn/Air Fuel Cells

Currently used in Las VegasElectrical Vehicle DivisionContain a central static replaceable anode cassetteTo refuel: discharged zinc-air module removed from the vehicle and is "refueled" by exchanging spent "cassettes" with fresh cassettes

Regeneration

Revolt

Swiss CompanyOpened U.S. center of operations - Portland

Disadvantages: They can't deliver sufficient powerThey lose a lot of power very quicklyThe cell dry out, becoming useless after only a few monthsThere is no satisfactory way to recharge them

The solution: ReVolt's new technology has a theoretical potential of up to 4x the energy density of Li-Ion batteries at a comparable or lower production costExtended battery life due to stable reaction zone, low rates of dry-out and flooding, and no pressure build-up problemsRechargeabilityCompact sizeCan manage the humidity within the cell

More on revolt

ReVolt

technology claims to have overcome the main problem with zinc-air rechargeable batteries--that they typically stop working after relatively few charges (air electrode can become deactivated)

For

electric vehicles: plan to use two flat electrodes – one containing zinc “slurry”

Air electrodes in the form of tubes

Zinc slurry is pumped through the tubes where it's oxidized, forming zinc oxide and releasing electrons

Revolt’s ev battery

Plan to increase energy density by increasing the amount of zinc slurry relative to the amount of material in the air electrode

Much like a fuel cell system or conventional engine – zinc slurry ~ fuel, pumping through the air electrode like gas in a combustion engine

Longer life span - from 2,000 to 10,000 cycles

As with fuel cells, may need to be paired with another type of battery for bursts of acceleration or regenerative braking

Zn/air vs. al/air

Al/Air: produces electricity from the reaction of oxygen in the air with aluminum

Has one of the highest energy densities of all batteries

Not widely used - cost, shelf-life, start-up time and byproduct removal, which have restricted their use to mainly military applications

An electric vehicle with aluminum batteries could have potentially ten to fifteen times the range of lead-acid batteries with a far smaller total weight

Mg/air Li/Air

High energy densitySafeInexpensiveNot been widely used - self-discharge in neutral solutionReaction mechanism of magnesium alloy anodeEffects of different additives on performance of Mg alloy in solution

Approach energy density of fuel cellsPolyPlusSingle use and rechargeable lithium metal-air – could power EvsTheoretically: max energy density 5,000+ watt-hours per kilogramLower self discharge rate and longer shelf life

conclusion

Many promising metal-air batteries:

Zinc/Air

Aluminum/Air

Magnesium/Air

Lithium/Air

Still mostly in developmental stages

Hope for use in electric vehicles in the future

References

http://news.cnet.com/8301-11128_3-10388553-54.html

http://www.technologyreview.com/energy/22926/

http://www.treehugger.com/files/2009/10/zinc-air-battery-revolt-3-times-more-energy-lithium-ion-battery-electric-cars.php

http://www.mpoweruk.com/zinc_air.htm

http://news.cnet.com/8301-11128_3-10388553-54.html

http://www.duracell.com/oem/primary/Zinc/zinc_air_tech.asp

http://www.revolttechnology.com/technology/revolt-introduction.php

http://www.technologyreview.com/business/23812/page2/