**3.3 Gelling agents in PCMs**

Gelling agents, or thickening agents, are added to PCMs to combat supercooling by altering their physical state to a semisolid or gel-like consistency, enhancing viscosity and cohesiveness. These agents help in stabilizing PCMs, preventing leakage, and improving handling. For instance, adding borax to Glauber's salt significantly reduces its supercooling from 15 to 3–4°C [24]. However, the effectiveness of these agents may decrease over time due to phase separation, agglomeration, or sedimentation. Common gelling agents include organic compounds, polymers, and inorganic materials like silica nanoparticles and clay minerals as given in **Table 2**.
