A lithium-ion battery or Li-ion battery is a type of rechargeable battery. Lithium-ion batteries are commonly used for portable electronics, smartphones, and wearables. The lithium-ion technology is a growing tech for energy stores in the military and aerospace industries too. Specially 12V lithium-ion batteries are becoming the future of the latest technology.
Every second we are using smartphones, there’s a chemical reaction, like a baking soda volcano happening inside of it. Inside the battery, there’s chemical a reaction that is continuously running. And without it, your phone would just be dead, which is something we’re all familiar with.
Let’s investigate this lithium-ion battery.
- How does it power your smartphone,
- what happens when you recharge it,
- Why does your battery die earlier and earlier in the day?
To answer these questions, let’s open up this battery and look inside.
How does lithium-ion batteries, power up the smartphone?
All batteries have a positive terminal and a negative terminal to supply power or electricity to our portable devices.
Electricity is essentially a flow of electrons. So as usual, flow from the negative terminal and run through the components like speakers, display and then end up at the positive terminal.
Where does this flow of electrons come from?
Well, this is a lithium-ion battery, so the electrons come from the element lithium.
At the negative terminal (anode); lithium atoms stored between layers of carbon graphite matrix. (Graphite) similar to the graphite in pencils.
Graphite has a crystal structure of layered planes. That allows for the lithium to be wedged in between each of the layers. Graphite functions as a stable storage space for lithium atoms. The technical term for this is intercalation.
One inherent property of the element lithium is that it doesn’t like its outer-most electron, and it wants to give it up. That’s how it can be stable by filling 8 electrons for its last band.
So when there is an available path from the negative terminal to the positive terminal, this electron separates from the lithium and starts heading to the other side. Now lithium becomes positively or +1 charged lithium-ion. When a lot of lithium atoms (electrons) leave the graphite at the same time, a flow of electrons is built up.
Positive Terminal of Lithium-Ion Batteries
Here we have Cobalt, which having [Ar] 3d7 4s2 configuration. And it’s become semi-stable by losing last 4s2 and 2 electrons from 3d. Thus making the Cobalt positive, or +4 charge.
As a result, it wants to gain back an electron. When connecting the negative and positive terminals, the electrons flow from the lithium, which wants to give up an electron, through the circuits and components in the smartphone. And to the Cobalt, which wants to gain an electron.
But now there is a small issue.
With the flow of electrons from the negative to the positive terminal, the cobalt side grows more and more negatively charged, and the other side positively charged.
Yes, the electrons do want to flow in this direction; but at the same time, electrons don’t like to flow to an area that is growing more and more negatively charged. This because of opposite charges attract, and similar charges repel.
To fix this, we give the chance to positively charged lithium ions, that recently left within the graphite matrix, to move to another side. Technically we call this path as Electrolyte. And its functions as media for lithium-ions to migrate to the other.
When lithium gets to the cobalt side, it again intercalates with the cobalt and oxygen to become Lithium Cobalt Oxide. But the lithium isn’t regaining its electron which went to the cobalt earlier.
It just neutralizes the charge build-up and keeps the reaction going.
Chemical reactions inside the Lithium-ion batteries.
C6 + LiCoO2 = LiC6 + CoO2
CoO2 + Li + e = LiCoO2
LiC6 = C6 + Li + e
At the end, almost all of the lithium has left the graphite layers, and joined the cobalt to become lithium cobalt oxide.
And the battery is now running on empty.