Preparation of Paraffin‐Sodium Alginate Core‐Shell Milli‐Spheres via Electrostatic Spraying and Their Application for Phase Change Energy Storage

ABSTRACT With globally increased demand for energy, the need for efficient energy storage is growing. Phase change materials such as paraffin wax were an effective means to meet the requirement of thermal energy storage. However, the leakage of paraffin wax during the solid–liquid phase transition process limited its application. To solve this problem, milli‐spheres with sodium alginate as the shell and paraffin wax as the core were firstly prepared using an electrostatic spraying technique. These were then chemically cross‐linked with toluene‐2,4‐diisocyanate to prepare PW@SA‐TDI phase change materials. The milli‐spheres were characterized using SEM, FT‐IR, DSC, TGA, and XRD. It was indicated that paraffin wax was successfully encapsulated within sodium alginate to form milli‐spheres, and there was no alteration to its chemical structure or crystal structure. The phase change temperature of milli‐spheres was comparable to pure paraffin. The introduction of SA enhanced the thermal stability, although the latent heat of phase change was slightly decreased relative to pure paraffin. At the ratio of 1.25% SA to 10.0% PW, the milli‐spheres exhibited high encapsulation efficiency with negligible leakage rate. This PW@SA‐TDI phase change material demonstrated favorable thermal property, dimensional stability, and leak resistance, which showed promising applications in energy storage and related fields.