A Novel TiZrHfMoNb High-Entropy Alloy for Solar Thermal Energy Storage.

Huahai Shen,Yiwu Mao,Haiyan Xiao,Xiaosong Zhou,Jutao Hu,Jianwei Zhang,Xiaotao Zu,Jinchao Zhang

doi:10.3390/nano9020248

Abstract

An equiatomic TiZrHfMoNb high-entropy alloy (HEA) was developed as a solar thermal energy storage material due to its outstanding performance of hydrogen absorption. The TiZrHfMoNb alloy transforms from a body-centered cubic (BCC) structure to a face-centered cubic (FCC) structure during hydrogen absorption and can reversibly transform back to the BCC structure after hydrogen desorption. The theoretical calculations demonstrated that before hydrogenation, the BCC structure for the alloy has more stable energy than the FCC structure while the FCC structure is preferred after hydrogenation. The outstanding hydrogen absorption of the reversible single-phase transformation during the hydrogen absorption–desorption cycle improves the hydrogen recycling rate and the energy efficiency, which indicates that the TiZrHfMoNb alloy could be an excellent candidate for solar thermal energy storage.

Highlights

Metal hydrides have been considered to be one of the most important solar thermal energy storage materials due to their advantages of high energy density, reversibility and thermal stability [1,2,3,4]
The solar energy is stored through the dissociation of metal hydride into its components and the heat energy is released again during the hydrogen adsorption of the metal [1,2,3,5]
The development of novel metal hydride materials with high storage capacity [6], good thermal stability [7,8] and reversible phase transformation during the hydrogen absorption–desorption cycle [9] is crucial for enhancing the applications of solar thermal energy

Summary

Introduction

Metal hydrides have been considered to be one of the most important solar thermal energy storage materials due to their advantages of high energy density, reversibility and thermal stability [1,2,3,4]. The development of novel metal hydride materials with high storage capacity [6], good thermal stability [7,8] and reversible phase transformation during the hydrogen absorption–desorption cycle [9] is crucial for enhancing the applications of solar thermal energy. The low oxidation resistances of Ti-H [9] and Zr-H [14] systems, the severe lattice expansion during hydrogenation and the disproportionation phenomenon of ZrCo-H restrict their applications in solar thermal energy storage. The hydrogenation performance and the phase transformation property of this new TiZrHfMoNb alloy were studied

Materials and Methods

Hf Hf

Before Hydrogenation

DSC TG