A lithium iron phosphate battery is like a really cool juice box that can store electricity instead of juice. The battery has three parts: a positive side, a negative side, and an electrolyte in the middle. Think of the positive side as the straw you drink the juice from, and the negative side as the bottom of the juice box where you push the straw through.
This battery uses lithium and iron phosphate to store energy, and they are both like special types of fruit that the juice box uses to make its juice super powerful. The juice inside the battery is made of a special kind of salt water that helps the lithium and iron phosphate move around and make electricity.
When you plug a device into the battery, like a phone, the energy flows from the positive side of the battery to the device through a wire. The more juice the device needs, the more energy flows out of the battery. When the battery is all out of juice, you can plug it into a wall outlet to recharge it, just like how you refill your juice box with more juice.
The cool thing about lithium iron phosphate batteries is that they are really good for the environment, kind of like how it's good to recycle your juice box instead of throwing it away. These batteries last a really long time and don't use any poisonous materials, so when they're old and need to be replaced, it's not as harmful to the Earth.