Redox mediators as charge agents for changing electrochemical reactions

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Redox mediators (RMs) are crucial for electrochemical systems but are less studied than other components.
• Understanding RMs is key to advancing energy storage and conversion technologies.

Purpose of the Study:

• To comprehensively review the effects of RMs on electrochemical systems.
• To elucidate the underlying redox mechanisms and reaction kinetics of RMs.
• To discuss the classification and properties of RMs in various applications.

Main Methods:

• Experimental and theoretical analysis of RMs.
• Review of RMs in lithium-ion batteries, Li-O2 batteries, Li-S batteries, decoupling electrolysis, supercapacitors, and microbial fuel cells.
• Classification of RMs based on their active reaction regions.

Main Results:

• RMs significantly enhance performance by decreasing electrode reaction polarization.
• RMs can be categorized into bulk, solid-solid interfacial, solid-liquid interfacial, and cell-unit types.
• Effective RMs offer improved charge transfer with minimal side-effects.

Conclusions:

• RMs fundamentally alter electrochemical system chemistry for improved efficiency.
• Further research into developing RMs with optimal charge transfer and reduced side-effects is warranted.
• This review provides a foundation for understanding and applying RMs in diverse electrochemical applications.