Shape-stable erythritol composite phase change materials with controlled latent heat release for spatiotemporally thermal energy utilization

Phase change materials (PCMs) have been extensively concerned recently as suitable medium for thermal energy storage due to their absorbing or releasing a large amount of latent heat in the phase change process. However, traditional PCMs usually crystallize spontaneously to release their latent heat in the cooling process, which greatly limits their practical application in thermal energy long-term storage and controllable release. Herein, we designed and synthesized a shape-stable erythritol (ERY)-based composite PCM with attractive performance of latent heat controlled storage and release using a facile aqueous fabrication route. In this composite, calcium ions cross-linked with sodium alginate is introduced to construct strong hydrogen bonding with ERY to increase the activation energy barrier for stabilizing supercooling, thus realizing long-term latent heat stored in supercooling state. The supercooled ERY composite can be maintained at room temperature for 50 days and subsequently controllably releases latent heat by thermal or mechanical trigger method. Meanwhile, the ERY composite exhibits excellent shape stability without any leakage over the phase change temperature. In addition, the crystallization enthalpy can reach 181.2 J/g, which can be maintained even after 80 thermal cycles, showing superior thermal energy storage capacity and repeatability. The crystallization kinetics study reveals that the crystallization mode of the ERY composite is three-dimensional growth spherical diffusion. This work provides an important strategy for the design and synthesis of shape-stable PCMs with controllable latent heat storage and release performance, which is of great prospect for the development of spatiotemporally thermal energy storage technology.