Performance management of EV battery coupled with latent heat jacket at cell level

Abstract

This numerical study evaluates the cell level performance management of an Electric Vehicle (EV) battery with Latent Heat (LH) jacket (as passive cooling). In this regard, a battery cell is conjugated with Phase Change Material (PCM) is assessed under continuous cycles of discharging and re-charging. This study is validated with numerical and experimental data with less than 1% deviation captured from literature for a Panasonic 18650 PF Lithium-ion (Li-ion cell). The thermal and electrical performance of key parameters is assessed with and without the existence of a PCM under various climatic conditions including extreme winter −20 °C, winter 0 °C, ambient 25 °C, hot summer 40 °C, and extreme hot/desert 55 °C temperatures. In addition, the choice of PCMs and circumferential jacket thicknesses around the battery (1 mm, 3 mm, 5 mm, and 7 mm) is evaluated in terms of thermal performance for multiple discharge/charge cycles under safe manufacturer operating conditions. Initially the PCM is in a solid state and results indicate that the conjugated thermo-chemical and electrical system is stable whilst LH is active however once fully melted, Sensible Heat (SH) dominates. This study shows, passive cooling maintains the thermal performance of the battery cell for longer, i.e., a 3 mm jacketed PCM as passive cooling results in a 340% thermal performance improvement in the number of consecutive discharge/charge cycles at ambient weather, 25 °C. At higher ambient temperatures (40 °C and 55 °C) improvement in thermal performances of up to 275% and 440% are achieved, respectively. At lower ambient temperatures at −20 °C and 0 °C thermals stability up to 162% and 160% with PCM respectively as opposed without for consecutive cycling. It is therefore concluded that efficient passive management is a feasible approach in reducing the harmful effects of overheating, including thermal runaway, thus improving the safety and performance of the electrical energy storage system (EES) in Electric Vehicles (EVs) and Hybrid Electric Vehicles (HEVs).