Self-healed inorganic phase change materials for thermal energy harvesting and management

Abstract

• First report on giving self-healing property to inorganic phase change materials; • Phase segregation and supercooling were inhibited by hydrogel and graphite; • Low-grade thermal energy harvesting and management were achieved. Inorganic phase change materials, especially for salt hydrate, possess superior energy storage density and thermal conductivity compared with organic phase change materials in low-grade thermal energy harvesting and management fields. More importantly, inorganic phase change materials are safer than that of organic phase change materials in terms of flammability and toxicity. While, supercooling associated with phase segregation and stability of inorganic phase change materials have heavily hindered them from wide practical application. On the other hand, relatively poor shape flexibility is another key drawback that will limit the application scope of inorganic phase change materials. With the aim at making the use of advantages of inorganic phase change materials and avoiding the above-mentioned drawbacks, firstly, sodium acetate trihydrate was used as a thermal energy storage medium, acrylamide and aqueous starch worked corporately, for the first time, to render self-healing (efficiency reach to 75%) and flexible property to the phase change materials composite, and the latent heat of the composite could reach to 134 J/g. In addition, interestingly, we found the addition of carbon material, graphite, could not only efficiently solve the supercooling, but also enhance cyclability of the composite phase change materials. Thanks to the self-healing and flexibility, the as-prepared materials could be used uneventfully in low-grade thermal energy harvesting and management of electronic and wearable device.