Energy and exergy analyses in battery systems created with different types of phase-change materials

Abstract The use of lithium-ion batteries is extensively common in electronic devices and electric vehicles due to their advantages such as high energy density and fast charging; however, their performance varies depending on temperature. The ideal working temperature of batteries is within the range of 15 °C and 40 °C, and temperature homogeneity must be ensured between modules. Battery thermal management systems (BTMS) are used to maintain batteries within their optimum operating temperature range, and phase-change materials (PCMs) are commonly used in BTMS. This study compares the exergy and energy efficiencies provided by six different types of PCM (RT35HC, RT38, RT42, RT44HC, disodium phosphate dodecahydrate, and lauric acid) at a discharge rate of 5C and four different dead state temperatures. As a result, similar to the results at all other ambient temperatures, the highest entropy production at 15 °C ambient temperature was 0.52 J K −1 and the exergy destruction was 148.94 J, while the lowest entropy production was observed in PCM_5, which has a low heat transfer coefficient and initial melting temperature, at 0.30 J K −1 . It was found that entropy production and, consequently, exergy destruction decreased with increasing ambient temperature. The exergy efficiency value varies depending on entropy production, battery temperature, and the exergy. At 15 °C, the maximum levels of exergy and energy efficiencies were recorded in PCM_5 at 64.9% and 85.1%, while the minimum values were recorded in PCM_6 at 56.3% and 78.9%, respectively.