Performance analysis of a thermochemical energy storage system for battery preheating in electric vehicles

For a sustainable future, electric vehicles (EVs) are expected to offer a superior alternative to conventional fossil fuel-based vehicles. However, the performance of lithium-ion batteries used in EVs is known to deteriorate at low temperatures. Hence, preheating of EV batteries becomes imperative in cold climates. In the present paper, a potassium carbonate salt hydrate-based Thermochemical Energy Storage System (TESS) is proposed for battery preheating. The Energy Storage Bed (ESB) is a reactor of this system in which hydration-dehydration reactions take place. The ESB is envisioned as a modular design that presents the advantage of scalability for different EV variants and ambient conditions. A 2-D model of ESB is developed and its performance is analysed by various parametric studies. The proposed TESS achieves cycle efficiency of 47.1 %, volumetric energy storage density of 153.4 kWh m- 3, and specific heating power of 88.6 W kg- 1. Further, the analysis is extended to study the temporal variation in the battery temperature of an electric car by the addition of the proposed TESS to the existing heating architecture. The effect of various parameters associated with the heating circuit, on the evolution of battery temperature is also studied. Using the proposed TESS, a heating rate of 0.43 degrees C min- 1 can be achieved for battery preheating of a typical electric passenger car.