Li-ion battery cells are temperature sensitive devices. Their performance and cycle life are compromised under extreme ambient environment. Efficient regulation of cell temperature is, therefore, a pre-requisite for safe and reliable battery operation. In addition, modularity-in-design of battery packs is required to offset high manufacturing costs of electric vehicles (EVs). However, modularity of battery packs is restricted by flexibility of traditionally used battery thermal management systems. For example, scalability of liquid cooled battery packs is limited by plumbing or piping and the auxiliary equipment used in the system. An alternative thermal management system is, therefore, required for modular EV battery packs. In this paper, state-of-the-art developed to control battery temperature near a pre-specified state is qualitatively reviewed with the intent to identify potential candidate for implementation in a modular architecture. Some of the novel techniques that provide high-scalability in addition to appreciable cost and energy-savings over traditional methods are also evaluated while considering the development state and associated technical risks. It is found that only a hybrid system can meet technical requirements imposed by modular design. Based on the current state, phase change materials and thermoelectric devices are more likely to be part of this next generation thermal management system.