1. Chemical Equilibrium The applications of fuel cells and secondary cells. Cho Sin Lui F.6A (2)

2. What is Chemical Equilibrium ? A chemical reaction is in equilibrium when there is no tendency for the quantities of reactants and products to change.

3. What is secondary cells? A secondary cell is any kind of electrolytic cell in which the electrochemical reaction that releases energy is reversible.electrolytic cellelectrochemicalreaction Eg. - Rechargeable batteries, in notebook computers, cell phones.Rechargeable batteries - Car batteries.Car batteries Secondary cell and battery

4. Information about secondary cells Cell type AdvantagesDisadvantages Lead acid battery -Inexpensive -simple to make -Well understood; -Dependable; -Low maintenance. -Low energy density; -Environmentally unfriendly; -Can't be stored in discharged condition. Nickel- cadmium battery -Fast charge; -Long life; -High number of charge/discharge cycles. -Low energy density; -Environmentally unfriendly; -Significant self-discharge.

5. Information about secondary cells Nickel metal hydride battery -High capacity; -High energy density. -Significant cost; -High self-discharge. Lithium-ion battery -Significant cost; -High self-discharge. -Subject to aging; -High cost. Lithium ion polymer battery -Can be very small -High energy density; -Safe. -Not yet widely available; -High cost.

6. Environment tips on batteries usage Choose primary batteries that are mercury and cadmium free; and use Ni-MH or Li-ion rechargeable batteries as far as possible. Choose rechargeable batteries as they can be reused several hundreds of times and are more amenable to recycling. Where battery recovery programme* is available, return batteries for recycling. Remove batteries from battery-operated equipment and recycle* them before disposing of the equipment. * Currently, only Mobile Phone Battery Recovery and Recycling Programme is available.Mobile Phone Battery Recovery and Recycling Programme

7. Fuel cells A fuel cell is an electrochemical energy conversion device which consume reactants and must be replenished.electrochemical How it works ? For more information: http://www.h2fc.com/technology.html

8. Applications of fuel cells Base load power plants Electric and hybrid vehicles. Electrichybrid vehicles Auxiliary power Off-grid power supplygrid Notebook computers for applications where AC charging may not be available for weeks at a time. Notebook computersAC Portable charging docks for small electronics (e.g. a belt clip that charges your cell phone or PDA).cell phonePDA

9. References Book - Comprehensive Chemistry (Physical Chemistry Ⅱ ) Websites - Chemical Equilibrium Chemical Equilibrium - Secondary CellSecondary Cell - Environmental concern of BatteriesEnvironmental concern of Batteries - Fuel cellFuel cell End