Lithium Ion batteries

Question 1

describe

Answer 1

At its most basic level, each Li-ion cell has three thin layers—a positive electrode made of a lithium alloy, a negative electrode made of carbon, and a third thin plastic or polymer layer between the two known as a “separator.” The separator performs two basic functions. First, of course, it keeps the positive and negative electrodes apart, preventing a short circuit. Second, it has tiny pores that permit lithium ions to flow between the two electrodes (from the positive to the negative electrode when charging, and in the reverse direction when discharging). The separator is bathed in a (typically flammable) liquid electrolyte such as ether, through which the lithium ions flow.

Question 2

if the seperator becomes damaged by for example mechanical damage what may happen

Answer 2

A problem arises if the separator becomes damaged or destroyed, causing the electrodes to short-circuit and overheat, initiating a chemical reaction between the electrolyte and the electrode. Such a short circuit can trigger a “thermal runaway” whereby the increase in temperature of the cell accelerates the chemical reaction, adding to the heat in turn and leading to the combustion of battery materials. Ultimately such a failure can trigger a chain reaction whereby successive cells in the battery burst into ever hotter flames.

Question 3

the electrolite is what

Answer 3

flammable normally Ether

Question 4

is there a difference between lithium andLITHIUM ION BATTERIES

Answer 4

Lithum (non-rechargeable) and Lithium-Ion (rechargeable) batteries. Both types are capable of ignition and subsequent explosion due to overheating. Overheating the batteries results in a thermal runaway, which can cause the release of either molten burning Lithium or flammable electrolyte. Once one cell goes into a thermal runway, it produces enough heat to cause adjacent cells go into thermal runaway, too. The resulting fire can flare repeatedly as each cell ruptures and releases its contents.

Question 5

how do you deal with and extinguish a lithium / lithim ion battery fire

Answer 5

Emergency procedure for lithium batteries of all types.

• Clear everyone from the area
• Ventilate the area with fresh air
• Use a respirator, eye protection and gloves while clearing up
• Disconnect the cell or battery if practicable in a way that prevents sparks and avoids contact with internal components
• Put the cell or battery in a remote, well ventilated area
• Only trained and qualified personnel should attempt to fight a lithium or lithium ion battery fire.
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Use plenty of water as a fine spray to swamp and wash away spilt liquid that may be corrosive. Do not use damp solids or small amounts of water as this increases the risks.
• In the event of a fire the material inside the battery may be released; this may be toxic and corrosive. If possible fight small fires with a graphite based dry powder extinguisher. First Aid information on specific chemicals contained in the cell can be found at www.inchem.org (used for COSHH risk assessment chemical information).
• If a graphite dry powder extinguisher is not available use copious amounts of fresh water as a fine spray to swamp the fire. This will not extinguish the fire immediately and will result in the lithium generating hydrogen; this may fuel a fire or explosion if it is not managed. Continue to use plenty of water until the fire is extinguished and the batteries are cooled. Be aware of the increased risk of explosion.