High-Performance Phase Change Materials Based on Nanotextured Cu Foam and Paraffin for Efficient Thermal Energy Storage

While phase change materials (PCMs) possess high energy storage capacities, they suffer from long charging/discharging cycles due to poor thermal conductivity. Existing solutions integrate PCMs with thermally conductive porous matrices but often compromise the energy storage capacity of the PCM composites. To overcome the trade-off between energy storage capacity and power density of PCM composites, this work proposes a facile solution by synthesizing Cu(OH)₂ nanowires on Cu foam to produce a nanotextured Cu matrix. Benefiting from the uniform distribution of Cu(OH)₂ nanowires and their large surface area, the adhesion between the metal foam and PCM and the charging/discharging rates were obviously improved, which resulted in the nanotextured Cu foam-PCM composite only requiring half the time to change phase compared to pure PCM, indicating outstanding heat conductance of the nanotextured Cu foam. Additionally, the nanotextured Cu foam-PCM composite performed 96% better than pure PCM in terms of temperature uniformity. As such, utilization of the nanotextured Cu foam drastically increased the power density of the composite PCM without compromising its storage capacity. It was also observed, for the first time, that the nanotextured Cu foam induces fast propagating dendrites that allow the PCM to quickly charge and discharge its thermal energy. This work demonstrates the potential of employing nano- and microstructures to enhance the performance of latent heat thermal energy storage systems.