Enhanced thermal performance of lithium nitrate phase change material by porous copper oxide nanowires integrated on folded meshes for high temperature heat storage

Abstract

Lithium nitrate has been highlighted as a high temperature phase change material with the melting temperature of similar to 256 degrees C for the applications of thermal energy storage. However, low thermal conductivity and corrosive property of lithium nitrate needs to be improved for wide applications. This report experimentally investigates thermal properties of a phase change composite consisting of lithium nitrate and porous copper oxide nanowires integrated on folded meshes. Specifically, porous copper oxide nanowires vertically aligned on the folded copper meshes with desired shapes are synthesized by carrying out chemical solution growth and subsequent heat treatment. Then, lithium nitrate is infiltrated in the network of the thermal conductive fillers under vacuum conditions. Our platform can provide a flexible geometrical configuration to enhance thermal performance by modifying the folded geometries to the target objects. As a result, the fabricated phase change composites with 7 vol% of filling materials exhibit the 6.7 times higher thermal conductivities than pure lithium nitrate, showing the excellent thermal transport by the fillers in the composite. Moreover, the porous copper oxide nanowires exhibit excellent anti-corrosive properties to lithium nitrate for stable operation under repeated phase change processes. Finally, the phase change composite heat storages exhibit the 1.3 times faster thermal charging and discharging characteristics than pure lithium nitrate ones.