Battery Technologies in Electric Vehicles: Improvements in Electric Battery Packs

Restrictions on fossil fuels and related environmental pollution issues motivate many organizations and countries to set their focus on electric vehicles (EVs) rather than conventional internal combustion engine vehicles [1], [2]. EVs require an energy storage system to store converted electric power in another form of energy and then reconvert the stored energy to electric power whenever it is required. The energy stored can be converted to electric energy for various uses, such as movement, lighting, and heating (although accessories are supplied by a 12-V auxiliary battery; the auxiliary battery is supplied by the main battery pack or by recuperative energy). Fortunately, many electrical energy storage technologies are available, with some offered commercially while others are in the research and development stage [3], [4]. Electrochemical energy storage systems use various technologies [5], [6]. Energy storage systems, the heart of EVs, are composed of battery cells, battery modules, and a battery pack. Researchers work on various sections of battery packs to improve their performance [7]. These sections are illustrated in Figure 1. As shown in the figure, some EV battery technology developers are studying chemical materials to increase the capacity, power, energy density, safety, and cell voltage. In the past century, the most common batteries for EV applications were Pb-acid and Ni-based batteries [8]. In current use, Li-ion-based batteries are at the top.