Experimental study of novel nickel foam-based composite phase change materials for a large-capacity lithium-ion power battery module

Thermal management strategies play an important role in the thermal safety of a power battery. Phase change material (PCM) cooling is considered the most competitive passive heat dissipation mode. In this paper, a novel nickel foam/paraffin (PA)/expanded graphite (EG) composite PCM (CPCM) is proposed for large-capacity prismatic lithium-ion battery modules. First, different proportions of nickel foam-based CPCMs were prepared. Second, the effects of different components of high thermally conductive additive EG on the thermal conductivity, thermal physical properties, thermal stability, and mechanical properties of the composites were studied in depth. Moreover, the fundamental reasons for the aforementioned property changes were analyzed from the microscopic point of view. The results showed that when the content of EG was 4 wt%, the thermal conductivity of the CPCMs approached the peak, which was 1.66 W/(m·K). The peak tensile strength and bending strength of the CPCMs were 2.75 and 6.59 MPa, respectively. The comprehensive analysis showed that adding 4 wt% of EG in the CPCMs was an optimum strategy. Eventually, these compound CPCMs were applied to a large-capacity prismatic lithium-ion power battery module. The experimental results demonstrated that compared with the natural air-cooling module and forced air-cooling module, the peak temperatures (Tmax) of the CPCM cooling module were decreased by 19.52% and 5.79%, and the peak temperature differences (Tmax − Tmin) were decreased by 38.15% and 35.41%, respectively. It is worth noting that even at a 1.5C high-rate uninterrupted charge/discharge cycle repeated five times, the highest temperature is always maintained below the safe temperature (55 °C), and the peak temperature difference is less than 5 °C, showing the dual advantages of the excellent temperature-controlling and temperature-equalizing abilities. The relevant outcomes will provide new ideas and theoretical value for the heat dissipation modes of large-capacity lithium-ion power batteries, ultimately promoting thermal safety performance.