Battery functional principle
During charging, the lithium-ions migrate through the electrolytes to the negative electrode. At the negative electrode, the lithium-ions react to form lithium atoms. This reaction takes place with the help of the electrons that are transported to the electrode via the outer current path. The lithium atoms insert themselves in the layers of the negative electrode material.
The reverse process occurs during discharging. The lithium atoms change into lithium-ions by releasing an electron. These migrate through the separator back to the positive electrode. At the positive electrode, the lithium-ions react with the electrons to form lithium atoms. The lithium atoms insert themselves in the structure of the positive electrode material.
The separator separates the positive and negative electrodes in order to avoid an internal short circuit. Simultaneously, it is permeable for the lithium-ions, so that the chemical reactions during charging and discharging can take place in the cell.