Lithium-ion batteries: How do they work? NARRATOR: The lithium ion battery is the power source for modern electric vehicles. These days, everyone's heard of lithium ion batteries. But what makes them so special? First of all, each battery is made up of many smaller batteries called cells. Let's take a closer look at one to see how it works. The electrical current reaches the cells via conductive surfaces. In this case, aluminum on one side and copper on the other. And just as in every other battery, there's a positive and negative electrode called the cathode and the anode. The cathode, or positive electrode, is made of a very pure lithium metal oxide. The more uniform its chemical composition, the better the performance and the longer the battery life is. As you'd expect, the anode, or negative electrode, is located on the other side. It's made of graphite, a form of carbon, with a layered structure. The battery is filled with a transport medium, the electrolyte, so that the lithium ions carrying the battery's charge can flow freely. This electrolyte must be extremely pure and as free of water as possible in order to ensure efficient charging and discharging. To prevent a short circuit, there's a layer placed between the two electrodes, the separator. To the tiny lithium ions, the separator's actually permeable. The experts call this property micro-porosity. Let's take a look at what happens when a battery is charged. The positively-charged lithium ions pass from the cathode through the separator into the layered graphite structure of the anode where they're stored. Now the battery is charged. When the battery discharges, that is when energy is removed from the cell, the lithium ions travel via the electrolyte from the anode through the separator back to the cathode. The motor converts the electrical energy into mechanical energy, making the car go. The amount of energy available and how long the batteries last is closely related to the quality of the materials used. To sum it all up, higher quality, purer materials, along with customized formulations, lead to longer battery life and better battery performance. BASF-- the chemical company.