Experimental study on the electrically-triggered crystallization behavior of supercooled copper foam-based and expanded graphite-based sodium acetate trihydrate

Phase change material is a promising solution to solve the mismatch between the energy demand and supply in solar energy applications. However, the inorganic phase change materials suffer from supercooling and poor thermal conductivity. This study aims at developing an electrically-triggered copper foam-based and expanded graphite-based sodium acetate trihydrate phase change composites to achieve the on-demand regulation of exothermic temperature and time and quick temperature response. First, the copper foam-based and expanded graphite-based sodium acetate trihydrate phase change composites achieving high thermal conductivity were synthesized. Then, a novel electrode with gradient rough structure was fabricated to trigger the crystallization of supercooled phase change composites. The DC voltage was only 1.5 V and the induction time was less than 5 s. The contradictory effects of copper foam and expanded graphite on both thermal conductivity and supercooling degree were simultaneously investigated, and stable supercooled phase change composites with high thermal conductivity were successfully explored. The cloudy dendrite grew instantaneously on the tip of the electrode once the DC voltage was exerted. After that, the electrically-triggered crystallization behaviours of the supercooled phase change composite were investigated. The experimental results indicated that the increase in thermal conductivity would accelerate the crystallization process and achieve a quick heat release and temperature response. These research findings would be useful in the development of intelligently on-demand energy storage technology. •Copper foam- and expanded graphite-based phase change composites were synthesized.•The PCCs achieved high thermal conductivity and stable supercooling properties.•The supercooled PCCs were electrically triggered, achieving controllable heat release.•The behavior of electrically-triggered crystallization of PCCs was investigated.