TY  - EJOU
AU  - Zhang, Yi 
AU  - Luo, Bing 
AU  - Li, Haibo 
AU  - Xu, Haigang 
AU  - Zhou, Dan 
AU  - Ding, Weijing 
AU  - Ding, Shuaijie 
AU  - Zhang, Guanmin 

TI  - Hydrogen Storage Materials for Metal Hydride Heat Pump Systems: A Review on Selection, Classification, and Performance Improvement
T2  - Frontiers in Heat and Mass Transfer

PY  - 
VL  - 
IS  - 
SN  - 2151-8629

AB  - Metal hydride heat pumps (MHHPs) are promising for utilizing low-grade renewable thermal energy and waste heat in building heating, cooling, and temperature-upgrading applications. System performance and reliability depend heavily on hydrogen storage materials, particularly on their thermodynamics, kinetics, capacity, thermal conductivity, and resistance to cyclic pulverization. This review systematically examines these materials thermodynamically and kinetically across MHHP cycles: thermodynamics define the pressure-temperature equilibrium and reaction direction, while kinetics govern absorption/desorption rates, ultimately determining thermal power output and system responsiveness. Based on these requirements, selection guidelines are summarized, emphasizing optimal operating pressures, high enthalpy, sufficient capacity, low hysteresis, rapid kinetics, good reversibility, and long cycle life. Four major alloy families (i.e., AB<sub>5</sub>, AB<sub>2</sub>, AB, and A<sub>2</sub>B) are critically analyzed alongside emerging alternatives such as A<sub>2</sub>B<sub>7</sub>-type La-Y-Ni alloys. To overcome performance bottlenecks, two complementary enhancement strategies are discussed: (i) thermal management via conductive additives and reactor design, and (ii) pulverization mitigation through compositional tuning, coatings, porous frameworks, and specialized forms (i.e., slurries, thin films, and amorphous alloys). Meanwhile, their economic feasibility, scalability challenges, and pilot-scale validation are discussed. Finally, future research directions are highlighted, including establishing comprehensive databases, developing high-precision kinetic models, evaluating real-world performance, and exploring novel alloys, all of which are essential for scaling MHHP technology toward sustainable energy deployment.
KW  - Metal hydride heat pump (MHHP); hydrogen storage materials; reaction kinetics; heat and mass transfer; thermal management

DO  - 10.32604/fhmt.2026.089136