MgCl2-MXene based nanohybrid composite for efficient thermochemical heat storage application

Abstract

Thermochemical heat storage is a practical approach for overcoming the challenge in solar energy applications. Herein, we synthesize a novel MgCl2/MXene (Ti3C2Tx) composite sorbent by impregnation method for low-temperature thermochemical heat storage application. Various techniques, including Thermogravimetric coupled with Differential Scanning Calorimetric (TG-DSC), X-Ray, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were applied to characterize the mechanical and thermal properties of MgCl2/MXene composites. The result showed that Ti3C2Tx possess a larger specific surface area and the hydrophilic groups allow maximum MgCl2 adsorption without structural distortion. The TG-DSC studies showed that the fourth DSC peak of MgCl2 (181.33 °C) is shifted in composites MX/Mg 15 % (159.63 °C) and MX/Mg 10 %, (141.67 °C) toward lower dehydration temperature. The cyclicability study demonstrated that in the 10 consecutive rehydration cycles, MgCl2 shows 45 % decrease in the enthalpy, while Mg/MX 10 % and Mg/MX 15 % composites record 4 % and 10 % decrease, respectively. Water uptake kinetics highlighted that at 85 % RH, the highest water sorption was recorded for Mg/MX 15 % where it absorbs 2.21 g/g mass. The energy storage density result reveals that the maximum loading rate of MgCl2·6H2O reaches 97.6 wt% for Mg/MX 15 % showed the highest enthalpy 2227 J/g at 85 % RH. Therefore, all the results indicate that MXene-based salt composites play an important role in thermochemical heat storage application, leading to a potential candidate for long-term heat storage.