Polypyrrole coated carbon nanotube aerogel composite phase change materials with enhanced thermal conductivity, high solar-/electro- thermal energy conversion and storage.

Phase change materials (PCMs) have been widely investigated as promising thermal management materials due to their high thermal storage capacity, satisfactory heat transfer rate and multi-responsive energy conversion and storage characteristics. In this work, a shape-stabilized solar-/electro- responsive thermal energy capture and storage system is proposed involving polypyrrole (PPy)-deposited carbon nanotubes (CNT) heterogeneous porous aerogel as a supporting matrix and the paraffin wax (PW) as a PCM. The composite PCMs obtained via integration of PW into aerogel supports present a relatively high thermal storage density of 160.9 J/g and outstanding phase transition stability even after 100 heating-cooling cycles. Furthermore, great enhancement of thermal conductivity (0.64 W/m·K, 2.56 times that of PW) is achieved in the composite PCMs by inducing PPy coating as a binder in the gap between CNTs. The mechanism of heat transport enhancement is explored by molecular dynamics simulation. It concludes that the in-situ polymerization of PPy through the vapor deposition method on the CNT aerogels effectively builds additional thermal transfer channels and enhances the heat transport between CNT by coordinating the carbon atom vibration. Herein, this reported stratagem may shed light on preparing composite PCMs with high thermal conductivity and multi-energy utilization functions.