CHAPTER EIGHTEEN - Safety of Lithium-Ion Batteries for Hybrid Electric Vehicles

Abstract

This chapter focuses on the safety concerns related to the use of Lithium–ion (Li–ion) batteries in hybrid vehicles. Lithium–ion (Li–ion) technology as an energy storage chemistry for hybrid and electric vehicles is developing rapidly, although presently the chemistry of choice in commercially available hybrid vehicles is still nickel metal hydride (NiMH). The consequences of a failure in a Li–ion battery tends to be more severe compared to other rechargeable battery chemistries as they have a higher energy density that results in the generation of more heat by the chemical reaction between the positive and negative electrodes. They also use a flammable organic solvent as the electrolyte that ignites and releases additional heat when exposed to the air. Often, a Li–ion cell fails in a manner that makes it inoperable; such a way makes them unable to be charged and/or discharged. In some instances, a Li–ion cell fails exothermically and the thermal runaway of a Li-ion cell occurs when the heat generated within the cell exceeds the heat dissipation by the cell. The use of adequate safeguards in the form of redundant protection circuits, well designed thermal management systems, and robust manufacturing processes coupled with battery designs can also minimize the risk of safety-related failure modes.