A one-step-assembled three-dimensional network of silver/polyvinylpyrrolidone (PVP) nanowires and its application in...

Creating ultralight monolithic metal foams remains an outstanding challenge despite their important applications, e.g., in electronics, sensors and energy storage. Herein, a facile methodology is developed for one-step fabrication of silver/polyvinylpyrrolidone (PVP) nanowire (AgPNW) hydrogel and high-quality robust ultralight AgPNW aerogel (AgPNWA) on a large scale. The hydrogel is directly formed by in situ assembling hydrothermally-synthesized AgPNWs. The resultant ultralight AgPNWA exhibits very high electrical conductivity. The application of this one-step fabricated AgPNWA to enhance phase change materials (PCMs) for high-efficiency thermal energy storage is investigated. The AgPNWA-paraffin composite (APC) shows ∼350% thermal-efficiency enhancement, ∼463% mechanical hardening, and strong reliability against thermal cycling due to the potentially strong AgPNW-paraffin interfacial interaction. It is also observed that the thickness of the APC shrinks significantly but there is no change in its diameter during thermal cycles. Analytical models of liquid capillary filling of deformable fiber-based 3D networks are derived for the first time and are applied to analyze the thermal-cycling-induced-shape-stabilization behavior of the APC and the vaporization-induced collapse behavior of the AgPNW network. This work provides important insights into designing a facile 3D assembly of nanomaterials, and thermal energy storage materials with high performance and reliability.