Batteries and Fuel Cells

Baghdad Batteries

• Almost 2000 years old

• Terracotta jars containing a copper cylinder separated from an iron rod by a non-conductive stopper, and filled with an electrolyte

Primary Batteries

Alkaline

Secondary Alkaline Batteries

• Self-discharge more quickly than primary batteries

• must not overcharge, quick charge, or let run empty

Lithium-Ion batteries

• more efficient than alkaline

• no memory effect

• higher energy density

• lower manufacturing costs

• more robust to physical damage

• can take on more shapes

Fuel cell

An electrochemical energy conversion device

Chemicals constantly flow into to….

the fuel cell, so it never goes dead

• as long as there is a flow, there is electricity

Most fuel cells in use today use..

hydrogen and oxygen as the chemicals

Corrosion

A natural phenomenon which attacks metal by chemical, electrochemical action converts metal into metallic compound, such as an oxide, hydroxide, or sulfate

Destruction or deterioration and consequent loss of solid metallic materials starting at its…

surface due to chemical or electro chemical attack, by their environment

Causes of Corrosion

1. presence of metal that will corrode (anode)

2. Presence of cathode

3. Presence of conductive liquid

4. electrical contact between anode and cathode

Pure or noble metals such as gold, silver, platinum, aluminum, copper do not corrode since…

they are chemically uncombined in their natural state

Classification of corrosion

dry corrosion

wet corrosion

Dry corrosion

Occurs when oxygen in air reacts with metal, and without the presence of liquid

• sensitive to temperature

• rate varies from metal to metal

Wet/electrochemical corrosion

• when two metals are in contact with a liquid, liquid containing salt and electric potential is formed between the metals

• in some cases a single metal when in contact with a liquid or an electrolyte, anode and cathode areas are created

Mechanism of corrosion

Will “eat” the anode, and deposit on the cathode

Active corrosion protection

• influence reactions which proceed during corrosion

• addition of inhibitors to aggressive medium

Passive corrosion protection

• mechanically isolating package contents from aggressive corrosive agents by using protective layers, films, coatings

• method neither changes ability of package contents to corrode nor aggressiveness of corrosive agent

Electrolysis

a process where the electrolytes are broken down into its constituent elements by passing electricity through it