Electric Vehicle Batteries

This introductory chapter deals with electric vehicle (EV) and its components. It mainly focuses on electric vehicle batteries. The operation of an EV is similar to that of an internal combustion vehicle. The major components of the EV are as follows—namely, an electric motor; an electronic control module (ECM); a traction battery; a battery management system; a smart battery charger; a cabling system; a regenerative braking system; a vehicle body; a frame; EV fluids for cooling, braking, etc.; and lubricants. A battery cell consists of five major components: (1) electrodes—anode and cathode; (2) separators; (3) terminals; (4) electrolyte; and (5) a case or enclosure. Battery cells are grouped together into a single mechanical and electrical unit called a battery module. These modules are electrically connected to form a battery pack, which powers the electronic drive systems. Traditional batteries include lead-acid (Pb-acid), nickel–cadmium (NiCd), and others that have used a liquid electrolyte. In many of the advanced batteries, the electrolyte is a gel, paste, or resin, including advanced sealed Pb-acid, nickel–metal hydride (NiMH), and Lithium (Li)-ion batteries. It is important to understand a variety of battery characteristics to evaluate battery suitability for unique applications, including the energy/power relationship (Ragone Plot), battery and cell impedance as a function of temperature, pulse discharge capability as a function of both temperature and load, and battery charge/discharge characteristics. The chapter also discusses the basics of fuel cell technology and developments in this technology. In case of the fuel cell, the energy is stored outside the electrodes. Thus, there is no physical limit to the amount of fuel stored.