Effect of carbon nanoadditives on lithium hydroxide monohydrate-based composite materials for low temperature chemical heat storage

Abstract

Carbon nanospheres (CNSs) and multi-walled carbon nanotubes (MWCNTs) as nanoadditives were used to modify lithium hydroxide monohydrate for low temperature chemical heat storage application. The lithium hydroxide monohydrate particles were well dispersed on the nanoscale level, and the diameter of nanoparticles was about 20-30 nm in the case of the carbon nanospheres and 50-100 nm the case of the MWCNTs, as shown by transmission electron microscopy characterization results. X-ray diffraction results indicated that the LiOH·H2O-carbon nano thermochemical composite materials were successfully synthesized. The thermochemical composite materials LiOH·H2O/CNSs (2020 kJ/kg), LiOH·H2O/MWCNTs (1804 kJ/kg), and LiOH·H2O/AC (1236 kJ/kg) exhibited obviously improved heat storage density and higher hydration rate than pure LiOH·H2O (661 kJ/kg), which was shown by thermogravimetric and differential scanning calorimetric (TG-DSC) analysis. It appears that nanocarbon-modified lithium hydroxide monohydrate thermochemical composite materials have a huge potential for the application of low temperature chemical heat storage.