Microdefect-Regulated Thermal Transport Mechanisms in Macroporous Metallic Gels for Safe Battery Thermal Management

Rapid charging and high-rate operation generate substantial heat in lithium-ion batteries, and insufficient heat dissipation can cause local heat accumulation and increase the risk of thermal failure. Macroporous metallic gels, represented by high-porosity open-cell metal foams, provide continuous heat transfer pathways and are promising media for battery thermal management. However, surface microdefects inevitably introduced during manufacturing and service can alter their thermal transport properties and consequently affect the accuracy of battery thermal safety prediction. In this study, open-cell aluminum and nickel macroporous metallic gels with spherical protrusions and depressions on the ligament surfaces were investigated. The effects of pore size (1–50 mm), contact angle (0–85°), defect volume fraction (0–10%), defect bottom radius (5–200 μm), and ambient temperature (300–400 K) on conductive, radiative, and total effective thermal conductivity were systematically investigated. The results show that increasing the protrusion content enhances heat conduction, whereas increasing the depression content significantly reduces the total effective thermal conductivity, with the maximum reduction approaching 90% when the defect content reaches 10%. Increasing the defect radius further strengthens the influence of depressions, particularly at smaller pore sizes. The calculated thermal conductivities of aluminum and nickel gels were applied to cylindrical and prismatic battery models to evaluate heating times from 300 to 350 K. Surface depressions slightly shortened the heating time, whereas protrusions generally prolonged it. The largest variation was observed, ranging from 153.415 to 153.500 s for cylindrical cells with nickel gels. These results provide a theoretical basis for defect-aware battery thermal management and safety prediction.