Lithium-ion (Li-ion) batteries are perhaps one of the most popular types of batteries today. They are used to power mobile phones, video cameras, laptops and other hi-tech mobile electronic gadgets.
A Li-ion battery is a good source of energy for these kind of gadgets because it is lightweight and can store a large amount of energy in a small space, making it very portable. It can also be recharge at a faster rate.
However, a Li-ion battery also has its drawbacks. One of which is that its shelf life is based on the time it was manufactured and not on the time of use or the frequency of charging and discharging. A Li-ion battery should also be stored in a place with low temperature because high temperature could shorten its shelf life. It might even explode when the temperature is extremely high!
As its name suggests, a Li-ion battery uses lithium ions instead of lithium metals. It also does not operate through the redox process which is common with other batteries. It contains electrodes and electrolytes.
The anode id usually graphite carbon while the cathode is lithium-cobalt dioxide (LiCoO2). These materials are used as electrodes because lithium ions can intercalate with them, that is, they can slip between the layers of atoms of these substances.
The electrolyte is any lithium salt dissolved in an organic solvent like ether. The salt could either be LiBF4, LiCIO4 or LiPF6. These substances disintegrate into their positive and negative ions once placed in the solvent. An organic solvent is used instead of water because a lithium metal may be produced under various conditions will explode when it comes in contact with water.
Aside from these, a Li-ion battery also needs a solid electrolyte interface (SEI) in order for it to function. Solid electrolytes and organic solvents are easily dissolved on anodes during charging. This inhibits the flow of ions, thus preventing battery activation. When the right organic solvents are used, the electrolytes form a SEI during the first charging. This prevents the decomposition of electrolytes after the second charging.
So, how does a Li-ion battery work? When the battery is charged, the electrons flow. This causes the lithium ion to move from the LiCoO2 cathode to the graphite anode with the aid of an electrolytic solution. This continues until the lithium ion reaches the maximum amount of energy that it can store and gives a signal that the battery is already full.
When the battery is being used (or discharged), the lithium ion goes back to the LiCoO2 through the electrolyte. The electrons, on the other hand, flow from the graphite to the LiCoO2 through the external circuit so as to balance the charge. This goes on until the battery loses its energy prompting the user to recharge it.
M.R. Ramos
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