Silicon dioxide-enhanced composite phase change materials for the thermal management of retired lithium-ion batteries

Abstract

Lithium-ion batteries (LIBs) have been regarded as the hearts of electric vehicles (EVs). However, the thermal safety of LIBs is considered to be a common and crucial technical issue, especially for large-scale retired LIBs. In this study, a novel composite phase change material (CPCM) based on paraffin (PA)/cubic boron nitride (CBN)/silicon dioxide (SiO2) was proposed and further utilized for decommissioned battery modules. First, CPCMs with different SiO2 ratios were prepared by employing a physical mixing melting method. Then the effects of different ratios of SiO2 on the thermal properties, thermal conductivity, thermal stability, mechanical strength, electrical insulation properties, and flow properties of the CPCMs were studied from macroscopic and microscopic perspectives. Eventually, the CPCM possessing 5 % SiO2 was used in the battery module for thermal management evaluation. The corresponding results indicated that even under the severe conditions of high temperature (40 °C) and a 1.5C higher discharge rate uninterrupted charge–discharge cycle, the maximum temperature and maximum temperature difference of the CPCM battery module were reduced by 8.45 and 5.40 °C, respectively compared with forced air cooling (FAC). This outcome can provide fundamental data and theoretical support for the thermal management strategy and thermal safety improvement of high energy density power systems.