**4. Issues of material compatibility with PCMs**

Material compatibility with PCMs is crucial for applications in thermal energy storage and temperature control systems. As PCMs undergo phase transitions between solid and liquid states, absorbing or releasing thermal energy, potential interactions with surrounding materials may cause compatibility issues such as chemical reactions, corrosion, and leakage. Selecting materials that are chemically stable, corrosion-resistant, and can accommodate PCM volume changes is vital for the reliable and efficient operation of PCM-based systems. Proper compatibility ensures enhanced PCM reliability and addresses issues arising from interactions with additives and adjacent materials, preventing PCM degradation and ensuring system longevity [82].

#### **4.1 PCMs with different metals and alloys**

PCMs are strategically paired with different metals and alloys to augment storage capabilities. For instance, paraffin wax is blended with aluminum, preparing composite exhibiting improved thermal conductivity. Eutectic salt mixtures, such as LiCl-KCl, are integrated with copper to enhance thermal conductivity, for efficient heat transfer. For high-temperature TES systems, the combination of calcium sulfate hexahydrate (CaSO4·6H2O) with copper proves invaluable. Copper enhances thermal conductivity, rendering it suitable for elevated temperature application. Additionally, sodium sulfate decahydrate (Na2SO4·10H2O) can be harmoniously merged with copper, ameliorating its thermal properties. Potassium nitrate (KNO3), when paired
