The Li₂SO₄-Na₂SO₄ System for Thermal Energy Storage

Area of Science:

• Materials Science
• Chemical Engineering
• Energy Storage

Background:

• High-temperature thermal energy storage (TES) is crucial for renewable energy integration.
• Solid-state TES materials offer advantages in stability and safety.
• The Li₂SO₄-Na₂SO₄ system was investigated for its potential in high-temperature TES applications.

Purpose of the Study:

• To evaluate the Li₂SO₄-Na₂SO₄ system as a candidate for high-temperature thermal energy storage.
• To theoretically analyze the system's performance using the Calphad method.
• To experimentally validate theoretical predictions and assess material performance.

Main Methods:

• Theoretical analysis using the Calphad method to determine thermodynamic parameters.
• Experimental synthesis and characterization of Li₂SO₄-Na₂SO₄ compositions (79/21 and 50/50).
• Testing of material reactivity, durability, and energy storage capacity under various conditions.

Main Results:

• Theoretical analysis identified promising compositions (79/21 and 50/50) with high theoretical enthalpies of transformation.
• Experimental enthalpies of reaction were measured as 185 J/g and 160 J/g for the studied compositions.
• The system demonstrated potential for TES, with preliminary cycling tests showing stability up to 20 cycles.

Conclusions:

• The Li₂SO₄-Na₂SO₄ system exhibits potential for high-temperature TES applications via solid-state reactions.
• Experimental results, while showing lower energy densities than predicted, confirm the system's viability.
• Further optimization, potentially through nanocrystallization, may enhance performance and overcome discrepancies between theoretical and experimental findings.