1. Batteries and Chemistry AP Chemistry Final Project
Derek Leung

2. Essential Questions
How do traditional, rechargeable, and lithium-ion batteries work?
How do chemical concepts explain the mechanisms behind batteries?
What advancements are being made for the future of batteries?

3. Thermodynamics and Energy
Batteries convert chemical potential energy into kinetic energy which can do work.
Conservation of Energy (1st Law of Thermodynamics)
Relationship between Free Energy and voltage
ΔG°cell = −nFE°cell
If E°cell > 0, spontaneous (galvanic cell)
If E°cell < 0, nonspontaneous

4. History of the Battery
1786, Luigi Galvani discovered “animal electricity”
1800, Alessandro Volta built the first practical battery
1859, Gaston Plante invented the first rechargeable battery with lead acid
1899, Waldmar Jungner invented the NiCd battery
1991, Sony commercialized the lithium-based battery

5. Lemon Battery Demonstration
Classic Example of Electrochemistry
Metals Used: Zinc (Zn) and Copper (Cu)
Half Reactions
Cathode: 2H+ + 2e-  H2 (reduction)
Anode: Zn  Zn2+ + 2e- (oxidation)
Is essentially....

6. Traditional Battery A battery is composed of many voltaic cells.
Most common non-rechargeable battery nowadays is the alkaline battery
Reaction between Zinc and Manganese (IV) oxide
Anode: Zn(s) + 2OH-(aq)  ZnO(s) + H2O(l) + 2e- [E°=-1.28]
Cathode: 2MnO2(s)+H2O(l) +2e-Mn2O3(s)+2OH-(aq) [E°=+0.15V]
E°cell = E°cathode - E°anode = 0.15V – (-1.28V) = 1.43V
In the case of AAA, AAA, C and D batteries, the more cells, the more current the battery can provide. Voltage stays the same.
Analogous to a water pipe
A battery is composed of many voltaic cells, which operate like the lemon battery.
The larger the cell, the more current the battery can provide. The voltage stays the same. To understand why, we can compare the flow of electrons to a water pipe. Voltage is the pressure of the water and current is the flow rate (amt of water/unit time). Because most electronics need a lot of current to operate (they need a lot of electrons flowing through), a larger battery is used to provide more electrons.

7. Rechargeable Battery
Rechargeable batteries work because they use reactions that are reversible.
Reactants <-> Products
External work needed
A reversible reaction is a reaction where the reactants form products, which react together to give the reactants back. Same pathway.
External work in the form of a direct electrical current is needed to build up the gradient of electrons and thus increasing the chemical potential of the cell. Explain diagrams.

8. Memory Effect
A con of rechargeable batteries such as nickel cadmium and nickel-hydride batteries
With each recharge, the battery holds less charge
Overcharging affects crystalline structures
Some types of rechargeable batteries include nickel cadmium and nickel hydride batteries. But a con of these is the memory effect. With each recharge, the battery holds less and less charge. This occurs when batteries are recharged before they are fully discharged.
The recharging reaction has to move Cd(OH) to the Cd electrode. The tendency of metals is for the grains to coalesce and form larger crystals. This is bad for the battery since it makes the cadmium harder to dissolve during high current discharge, and leads to high internal resistance and voltage depression.

9. Lithium Ion Battery Cons?
Lithium ions are a type of rechargeable battery with high energy density and tiny memory effect.
Cathode: Metal oxide
Anode: Carbon
Electrolyte: lithium salt in organic solvent
Cons?
Used in portable electronics, military uses, battery electric vehicles and more. Explain diagrams.
There are, however, a few cons associated with the Lithium-ion battery. The lithium salt organic solution is highly flammable and have to be kept pressurized. There have been many accidents reported such as explosions as well as battery recalls by some companies.

10. Non-rechargeable vs. Rechargeable
What happens when one attempts to recharge a traditional battery?
Actually, one can recharge a regular battery.
However... there are concerns.
Efficiency
Voltage and Safety
The reaction taking place in an alkaline battery is actually reversible, which means an external source can recharge an alkaline battery. However, the battery must undergo the reverse reaction efficiently, so that more cycles are possible. Efficiency is how closely the electrode materials are returned to their original physical state. Alkaline batteries are not very efficient, so it performs poorly with each recharge. Within the electrode, filamentary structures may form and increase the likelihood of short circuiting.
Voltage is also another concern because the right voltage is needed to drive the electrons and build the potential as explained in the previous slide. Too low of a voltage and no charge is built, too high of a voltage and the battery overheats which may cause explosions, fire, and/or leaks. So the problem with voltage is that it’s difficult to obtain or build a charger that can supply the right voltage.

11. Future of Batteries Disposal and Recycling
Alkaline batteries can be disposed.
Mercury and heavy metals
Lithium Ion batteries should be recycled.
Car batteries should be brought to waste management centers.
Improved performance and safety
Lithium-air batteries
Solid-state batteries
This slide covers the future of batteries, which is important because batteries play a very important role in powering our everyday electronics. Disposal and Recycling of batteries touch upon the chemical properties of certain metals found in batteries.
Alkaline batteries: Before 1980, many alkaline batteries contained mercury and other heavy metals. But since then, alkaline batteries are composed of common metals (steel, zinc, and manganese) so they do not pose health risks during disposal.
Lithium ion batteries: Contain chemicals such as lithium and zinc-air, so one should recycle them. Stores nowadays, such as Best Buy, have centers for battery recycling.
Car batteries: Contain lead which can pose health hazards. Waste management centers can recycle car batteries, and many retailed will buy back used car batteries for recycling
Companies are aware of the limitations of lithium-ion batteries and are researching new, efficient batteries. One of these are the lithium-air batteries which use oxygen as the oxidizer rather than a material. The batteries are light and cheap, and can last longer. It is about 5 to 10 years from becoming a reality.
Solid-state batteries are being designed so that the battery is of only solid components. This makes usage safer, as the risk of leaks and fires are reduced.

12. Works Cited
"Battery Care, Use and Disposal | Duracell Batteries." Duracell Batteries. N.p., n.d. Web. 25 May Brown, Theodore L., H. Eugene LeMay, and Bruce Edward. Bursten. "Chapter 20 Electrochemistry." Chemistry: The Central Science. Upper Saddle River, NJ: Prentice Hall, Print. Buckle, Kenneth. "How Do Batteries Store and Discharge Electricity?” Scientific American (2006): n. pag. Print. Lerner, Michael. "How Do Rechargeable (that Is, Zinc-alkaline or Nickel-cadmium) Batteries Work and What Makes the Reactions Reversible in Some Batteries, but Not in Others?" Scientific American (1999): n. pag. Scientific American. 21 Oct Web. 25 May Roberts, Royston M. "The Electric Battery and Electromagnetism.” Serendipity: Accidental Discoveries in Science. New York: Wiley, Print.