Thermally conductive phase change composites featuring electrospun lignin nanofiber carbon aerogels for efficient solar-thermal energy conversion and storage

Phase change materials (PCMs) have been recently introduced as key thermal energy storage medium in several thermal applications, specifically in solar thermal energy. However, the feasibility of their application in solar thermal storage has been limited by leakiness during solid-liquid phase conversion, low thermal conductivity, and low energy conversion rate. Herein, the poly (ethylene glycol) (PEG)-based PCMs (LNCAs/PEG/E51) were constructed via vacuum impregnation technology, employing the electrospinning lignin nanofiber carbon aerogels (LNCAs) as the supporting materials , heat conduction path and photothermal agent. And the in situ cross-linking epoxy resin (E51) was used to further prevent leakage and enrich the thermal conductive network. The thermal conductivity of LNCAs/PEG/E51 was 0.67 W·m −1 ·K −1 , which was about 3 times higher than that sample without the LNCAs. It also exhibited a high latent heat of fusion (87.95 J·g −1 ), favorable stability over 100 heating-cooling cycles, and thermal stability below 224.78 ℃. The solar-thermal energy conversion and storage efficiency of LNCAs/PEG/E51was higher to 81.72 % owning to efficient non-radiative transition of electrons. For the first time, we used LNCAs as support, thermal conductive and photothermal matrix for PCMs. The study established a channel for simultaneous high-value utilization of lignin and solar energy, which has reference value to some extent.