Synthesis and Characterization of Doped Magnesium Hydroxide for Medium Heat Storage Application

Area of Science:

• Materials Science
• Energy Storage
• Thermochemistry

Background:

• The UK generates substantial waste heat annually, exceeding electricity demand, necessitating efficient recovery technologies.
• Thermochemical energy storage (TCES) offers a promising solution for recovering and storing waste heat across various temperatures.
• Magnesium hydroxide (Mg(OH)2) is a potential TCES material but its high dehydration temperature limits its use in medium-temperature applications.

Purpose of the Study:

• To investigate the effect of potassium nitrate (KNO3) doping on the thermochemical properties of Mg(OH)2.
• To evaluate the potential of doped Mg(OH)2 for medium-temperature waste heat storage applications.

Main Methods:

• Development and characterization of Mg(OH)2 samples doped with 5, 10, 15, and 20 wt% KNO3.
• Evaluation of dehydration temperature and energy storage capacity.
• Assessment of surface topology and thermal stability through non-isothermal testing.

Main Results:

• The Mg(OH)2 sample with 5 wt% KNO3 exhibited optimal performance.
• Dehydration temperature decreased from ~317 °C to 293 °C.
• Energy storage capacity increased from 1246 J/g to 1317 J/g.
• The 5 wt% KNO3 doped sample demonstrated a stable surface topology and thermal stability.

Conclusions:

• Doping Mg(OH)2 with 5 wt% KNO3 effectively lowers its dehydration temperature and enhances energy storage capacity.
• This modified material shows significant potential for medium-temperature heat storage applications (293 °C to 400 °C).
• The findings contribute to advancing waste heat recovery and utilization technologies.