Abstract
Electrically insulating phase change composite materials (PCCMs) with lightweight, good thermal management performance, high stability and high mechanical strength are strongly desired for lithium-ion battery (LIB) thermal management. This research study presents a group of PCCMs based on the integration of reduced graphene-oxide aerogel beads (rGOAB), phase change materials (PCMs) and thermally conductive silicone rubbers (SRs). To demonstrate the thermal management performance, a 3 × 3 square 18650 LIB module was inserted into a SR pack. The temperature reduction (temperature reduction of the battery cells at the hottest point in the SR pack compared with in air) reached 8.6 °C, 13.0 °C and 14.7 °C at 1C, 2C and 3C discharge rate, respectively, at a concentration of 20 wt% PCM beads in SR with thermal conductivity of 0.5 W/mK. The specific energy reduction of above-mentioned pack is only 15.8%, substantially lower than the commercial level (above 30% to 40%). The lowest specific energy reduction in SR pack with thermal conductivity of 0.3 W/mK goes down to 13.4%, indicating its remarkable lightweight and high energy density features. The effects of PCM-encapsulant type, SR matrix thermal conductivity and bead size on LIB temperature reduction were also discussed. The heat transfer mechanism between the matrixes and rGOAB/PCM was thoroughly explained. Mechanical properties and battery thermal management performance of the composites were systematically examined. The rGOAB/PCM@SR composites exhibited more than 10 times of impact strength compared with expanded graphite-based PCCMs and higher compressive toughness above the phase transition point.
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