Controllable Solid Electrolyte Interphase by Ionic Environment Regulation for Stable Zn-Ion Battery

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Artificial solid electrolyte interphase (SEI) layers are crucial for stable aqueous zinc ion batteries.
• Understanding the influence of ionic environments on SEI formation is vital for optimizing battery performance.
• Previous research has not fully explored how different ionic conditions affect SEI properties and battery cycling.

Purpose of the Study:

• To investigate the impact of various ionic environments on the formation and properties of artificial SEI layers.
• To analyze the relationship between ionic environment, reaction spontaneity, and SEI effectiveness.
• To characterize the protective mechanism of the SEI layer on the zinc anode.

Main Methods:

• Utilizing pyromellitic acid (PA) as an organic ligand to coordinate with Zn2+ under diverse ionic conditions.
• Analyzing the spontaneity of reactions within different ionic environments.
• Fabricating and testing PA-Zn symmetric cells and PA-Zn//MVO full cells.

Main Results:

• A PA solution at pH 4, lacking hydroxide ions (OH-), formed a dense, ultrathin SEI layer with effective Zn-PA coordination.
• This SEI layer successfully prevented direct contact between the zinc anode and the electrolyte.
• The organic functional groups in the SEI facilitated a uniform flux of Zn2+, enabling stable cycling for over 3500 hours at 3 mA cm-2 in a symmetric cell.
• The PA-Zn//MVO full cell exhibited excellent electrochemical reversibility.

Conclusions:

• The ionic environment significantly influences SEI generation and effectiveness in aqueous zinc ion batteries.
• Optimizing ionic conditions, such as using PA at pH 4, can lead to superior SEI formation and enhanced battery stability.
• This study provides valuable insights for developing novel SEI strategies for advanced zinc-based energy storage systems.