Self-discharge refers to the loss in stored charge of a battery without connection between its electrodes as a consequence of internal chemical reactions. Self-discharge processes can be tested in a loadfree state for a fixed time. Two self-discharge reactions are possible in a Li-ion cell: one is chemical and the other electrochemical. Because of their reactivity, charged cells can undergo side reactions, and factors such as purity of the active material or electrolyte, the specific surface area of the electrodes, conductors, binders or separators can have effect on the self-discharge performance. These reactions are mostly irreversible while electrochemical reactions can be reversible. For example, lithium re-intercalation can lead to self-discharge of Li-ion batteries, as has been demonstrated by many researchers who have studied the different factors that could affect self-discharge of