In recent research, scientists have tackled the challenge of leakage in phase change materials (PCMs) by employing waste coffee grounds-based biochar (WCG) as a support material for composite PCMs. The study involved carbonization and chemical modification to enhance the properties of the alkali-modified biochar (OH-WCG). Notably, the OH-WCG demonstrated a significant increase in surface area, measuring 21.9 times that of untreated biochar. The resulting composite PCMs, WCG/Paraffin wax (PW), prepared through the melt impregnation method, exhibited a thermal conductivity boost of 43% compared to pure PW.

Key findings include the development of leak-free composite PCMs (OH-WCG-40), requiring only 40 wt% of modified biochar to prevent paraffin leakage even after 300 cycles. Differential scanning calorimetry (DSC) analysis indicated that OH-WCG-40 displayed a phase transition temperature of 46.28 °C and a melting enthalpy of 97.69 J/g. Importantly, the composite PCMs demonstrated stability with minimal mass change after 300 cycles.

The study underscores the need for optimizing latent heat storage technology, particularly for renewable energy utilization. By addressing the limitations of PCMs, such as poor thermal conductivity and leakage issues, this research contributes to the development of effective thermal energy storage systems. The use of alkali-modified biochar as a support material showcases its potential in enhancing the thermal performance of PCMs, making them suitable for temperature regulation in buildings and solar energy recycling. Additionally, the study highlights the practicality of utilizing waste coffee grounds as a sustainable raw material for biochar production, aligning with environmental conservation and efficient energy practices.