As discussed in Chapter 14, lithium-ion batteries can be classified based on the electrolyte used as lithium-ion batteries (liquid electrolyte), polymer lithium-ion batteries (gel polymer electrolyte), and solid lithium-ion batteries (solid electrolyte). Of course, batteries can also be classified according to the capacity or size into large, general-purpose, and micro batteries. Large batteries are meant for large machines or devices such as electric vehicles (EVs), aerospace, and load leveling. General-purpose batteries are used for common electronics such as mobile phones, portable computers, videos, and digital cameras. Micro batteries are used in microelectromechanical systems (MEMSs), such as tiny scouts or drones, or micromotors. On the other hand, batteries can also be classified based on their positive or negative electrode materials, and models [1]. In the following discussion of lithium-ion battery applications, they will not be treated separately.