Multiple Potentials of Maximum Entropy for a Na₂Co[Fe(CN)₆] Battery Electrode Material: Does the Electrolyte...

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Efficient energy storage solutions are critical for balancing energy generation and consumption.
• Aqueous sodium-ion batteries (Na-ion) are promising for large-scale energy storage.
• Understanding intercalation mechanisms in Na-ion batteries remains a challenge.

Purpose of the Study:

• To investigate the electrode/electrolyte interface in electrodeposited Na2Co[Fe(CN)6] films within aqueous solutions.
• To explore the electrochemical behavior and interfacial phenomena in these Na-ion battery systems.
• To understand the influence of electrolyte composition on interfacial processes.

Main Methods:

• Fabrication of electrodeposited Na2Co[Fe(CN)6] films.
• Electrochemical characterization in aqueous electrolyte solutions.
• Analysis of interfacial properties using potentials of maximum entropy (PMEs).

Main Results:

• Observed up to three distinct potentials of maximum entropy (PMEs) in the investigated systems.
• The existence of multiple PMEs in electrochemical systems is reported for the first time.
• PMEs are correlated with interfacial water structure and depend significantly on electrolyte anion properties, likely hydration energy.

Conclusions:

• The study reveals novel interfacial behavior in aqueous Na-ion batteries, evidenced by multiple PMEs.
• Interfacial water structure plays a crucial role in mass and charge transfer.
• Electrolyte composition, particularly anion hydration energy, significantly influences interfacial processes, offering insights for battery design.