The main issue with batteries, from the perspective of the automakers, is that they require a complex understanding of the interactions between chemical, electrical and thermal effects and these complex parameters must be fully understood and optimized to ensure that the battery temperature is maintained. Not controlling the battery temperature can have serious consequences as even slight deviation from the optimum temperature can result in a dramatically shortened life time and serious safety hazards. Passive thermal management systems using a PCM can control the temperature differentials and maintain temperature uniformity in the Li-ion batteries. This offers a cost effective cooling solution without the need for expensive addition of components such as fans, blowers or pumps.