1. Zinc Air Batteries
By: Ana Brar

2. General Information
Oxygen from air
Activated when oxygen is absorbed into the electrolyte through a membrane
Usually reaches full operating voltage within 5 seconds of being exposed to air
Oxygen diffused directly into battery
Electrolyte that catalytically promotes the reaction of oxygen, but is not depleted or transformed at discharge
Zinc and alkaline electrolyte
Button cell

3. Advantages Weight - not necessary to carry a second reactant
High energy density
Competitive with Lithium-ion
Inexpensive materials
Flat discharge voltage
Safety - don't require volatile materials, so zinc-air batteries are not prone to catching fire like lithium- ion batteries
Excellent shelf life, with a self-discharge rate of only 2% per year
Available in a range of button and coin cell sizes
Rechargeable high power fuel cells in the process of development
Environmental benefits
Have high volumetric energy density compared to most primary batteries

4. Disadvantages Sensitive to extreme temperature and humid conditions
Carbon dioxide from the air forms carbonate which reduces conductivity
High self discharge (after seal is broken)
After activation, chemicals tend to dry out and the batteries have to be used quickly
Although recharging is possible for fuel cells, it’s also inconvenient and is only suitable for high power types
Zinc air batteries must be larger to satisfy high current needs
High power batteries use mechanical charging in which discharged zinc cartridges are replaced by fresh zinc cartridges—therefore the used cartridges must be recycled
Have flooding potential
Limited output
When zinc turns it into zinc oxide it expands, space

5. Common uses Hearing Aids Watches Mobile phones Digital Cameras Pagers
Power sources for electric fences
Recharging Li-Ion batteries
Transportation:
Cars - EVs
Buses

6. 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

7. Transportation Would use Zn/Air Fuel Cells Currently used in Las Vegas
Electrical Vehicle Division
Contain a central static replaceable anode cassette
To refuel: discharged zinc-air module removed from the vehicle and is "refueled" by exchanging spent "cassettes" with fresh cassettes
Regeneration

8. Revolt Swiss Company Opened U.S. center of operations - Portland
Disadvantages:
They can't deliver sufficient power
They lose a lot of power very quickly
The cell dry out, becoming useless after only a few months
There 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 cost
Extended battery life due to stable reaction zone, low rates of dry-out and flooding, and no pressure build-up problems
Rechargeability
Compact size
Can manage the humidity within the cell

9. 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

10. 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

11. 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

12. Mg/air Li/Air High energy density Safe Inexpensive
Not been widely used - self-discharge in neutral solution
Reaction mechanism of magnesium alloy anode
Effects of different additives on performance of Mg alloy in solution
Approach energy density of fuel cells
PolyPlus
Single use and rechargeable lithium metal-air – could power Evs
Theoretically: max energy density 5,000+ watt-hours per kilogram
Lower self discharge rate and longer shelf life

13. 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

14. References http://news.cnet.com/8301-11128_3-10388553-54.html
battery-revolt-3-times-more-energy-lithium-ion-battery- electric-cars.php
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