Computational and Experimental Study of Li-Doped Ionic Liquids at Electrified Interfaces

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Ionic liquids are promising electrolytes for energy storage devices.
• Understanding the electric double layer (EDL) structure and dynamics is crucial for optimizing performance.
• The effect of Li-salt doping on ionic liquid EDL properties requires further investigation.

Purpose of the Study:

• To investigate the influence of Li-salt doping on the dynamics, capacitance, and structure of three ionic liquid electrolytes.
• To analyze the properties of the electric double layer (EDL) at the electrode-electrolyte interface.
• To correlate computational findings with experimental capacitance measurements.

Main Methods:

• Molecular dynamics simulations with polarizable force fields.
• Calculation of EDL formation rates, energy storage capacities, and differential capacitance.
• Experimental capacitance measurements on glassy carbon electrodes.

Main Results:

• EDL formation rates are in the hundreds of picoseconds, minimally affected by Li-salt.
• Li-salt doping reduces asymmetry in differential capacitance profiles, aligning computational and experimental data.
• Li+ ions induce disorder in the EDL due to strong anion binding, localizing in the second molecular layer.

Conclusions:

• Li-salt doping significantly impacts ionic liquid electrolyte capacitance and EDL structure.
• Computational and experimental results provide insights into electrode-electrolyte interactions and energy storage mechanisms.
• Predicted specific energy at ideal graphite electrodes based on computed capacitance and electrochemical windows.