Question: what happens when you charge an iPad and how does it work

Jemma Rowlandson answered on 24 Jan 2017:

Awesome question! So your iPad contains something called a lithium-ion battery. Lithium is just a chemical element, and it’s really tiny. A battery is all about creating electrons, which make up electricity, so you can use them to charge your iPad/phone or whatever. A battery is made up of two electrodes, which are connected by a wire, and also has something called an electrolyte sandwiched between them. A great diagram of how charging and discharging a battery works is here, take a look:

When you are using your iPad (discharging the battery) inside the battery at the first electrode (called the anode) lithium looses an electron and travels across the electrolyte to the other side. The electron it has lost cannot cross the electrolyte and so instead it travels around the wire powering your iPad. The lithium and electron then find each other again on the other side in the second electrode (called the cathode). Just like a mini love story. When you charge your iPad the opposite happens. The lithium and electron separate again and move from the cathode back to the anode, where again they find each other. This happens every single time you charge and then discharge your iPad battery.

So you know how batteries get worse with time? Especially phone batteries? This is all down to the lithium and it’s electron too. After a while the materials either side begin to break down, making it more difficult for lithium to escape. With fewer lithium and electrons moving across, your battery holds less charge.