Crystal Phase Ionic Liquids for Energy Applications: Heat Capacity Prediction via a Hybrid Group Contribution...

Area of Science:

• Thermodynamics
• Materials Science
• Chemical Engineering

Background:

• Heat capacity is crucial for designing ionic liquids (ILs) for applications like thermal energy storage.
• Existing models predict liquid phase heat capacity, but none exist for the solid crystal phase of ILs.
• Solid phase heat capacity is vital for ILs used in solid-state thermal energy storage.

Purpose of the Study:

• To develop and validate a predictive model for the crystal phase heat capacity of ionic liquids.
• To address the gap in existing literature regarding solid-state IL properties.
• To facilitate the design of ILs for solid-phase applications.

Main Methods:

• A hybrid group contribution model (GCM) was extended and modified from a liquid phase model.
• A comprehensive database of over 5000 data points from 71 unique crystal phase ILs was utilized.
• The model incorporates anion/cation core effects, subgroup contributions, and indirect parameters for branching and distribution.

Main Results:

• The developed hybrid GCM reliably predicts crystal phase heat capacity.
• The model achieved a mean absolute percentage error of 6.78% in predictions.
• The model accounts for anion core, cation core, and subgroup effects, plus branching and distribution.

Conclusions:

• The study successfully developed the first predictive model for crystal phase heat capacity of ionic liquids.
• The model's accuracy (6.78% MAE) supports its reliability for practical applications.
• This research enables informed design of ILs for thermal energy storage and other solid-phase applications.