Hexadecylamine@silica nanocapsule with excellent operational reliability for thermal energy storage

Hexadecylamine (HDA) was in situ encapsulated into SiO 2 nanoshells, to obtain the HDA@SiO 2 nanocapsule with excellent thermal reliability during the process of energy release/storage. Closed-pore structured HDA@SiO 2 nanocapsule was successfully synthesized. The latent heats of crystallization and melting for HDA@SiO 2 nanocapsule are 189.3 and 193.8 Jg −1 , with the 91.2 wt% encapsulated HDA in the nanocapsule. The crystallization and melting temperatures ( T C ${\mathit{T}}_{\mathrm{C}}$ and T M ${\mathit{T}}_{\mathrm{M}}$ ) are 33.34 °C and 49.53 °C for HDA@SiO 2 nanocapsule, respectively. After undergoing 200 thermal cycles, the latent heats of HDA@SiO 2 nanocapsule decreased by 0.16% and 0.46% with the unchanged phase transition temperature, indicating HDA@SiO 2 nanocapsule has superior operational reliability. Moreover, the thermal conductivity of HDA@SiO 2 is 0.13 Wm −1 K −1 , an approximately 20% improvement over that of pure HDA. The temperature of degradation and evaporation of HDA@SiO 2 nanocapsule was increased by more than 10 °C compared with that of bulk HDA. The HDA@SiO 2 nanocapsule exploited in this work exhibits excellent operational reliability and high latent heat during the process of energy release/storage, which makes it more suitable and competitive in the recycling and utilization of thermal and solar energy.