Lithium Ion Battery
Lithium iron Phosphate battery (LiFePO4) has a nominal voltage of 48VDC. It is comprised by 16 cells of 3.2V each. The internal structure of LiFePO4 battery cell is shown in the figure on the right. Shown is the olivine structure of LiFePO4 as the positive electrode of cell. Aluminum foil functions as current collector of positive pole. A polymer membrane separates positive and negative electrodes of the cell. The electron (e-) can't pass through the polymer separator but Li+ can pass through it freely. The negative electrode which consists of graphite is shown in the figure on the right. Copper foil is the current collector of negative electrode. There is organic electrolyte in the cell which is sealed by Al-plastic composite film.