Artificial solid electrolyte interphase for aqueous lithium energy storage systems.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous lithium energy storage systems offer sustainability and safety advantages over nonaqueous systems.
• However, capacity fading during cycling and float charging limits their practical use.
• Developing stable interfaces is crucial for enhancing aqueous battery performance.

Purpose of the Study:

• To introduce and evaluate a graphene-based artificial solid electrolyte interphase (G-SEI) for aqueous lithium batteries.
• To investigate the impact of G-SEI on cycle life, capacity retention, and float charge stability.
• To explore the mechanism by which G-SEI enhances electrochemical performance.

Main Methods:

• Fabrication of graphene films as artificial SEI (G-SEI) on LiMn2O4 cathodes using Langmuir trough techniques.
• Precise control over G-SEI thickness (1-50 nm) and surface area (1 cm² to 1 m²).
• Electrochemical testing including charge-discharge cycling and float charge measurements.

Main Results:

• An aqueous battery with a 10-nm G-SEI achieved 104 mA·hour g⁻¹ after 600 cycles, a 26% improvement over controls.
• Float charge current density was reduced to 1.03 mA g⁻¹ after 1 day, a 54% decrease compared to controls.
• G-SEI suppressed LiMn2O4 Jahn-Teller distortion and conductive carbon oxidation, enhancing stability.

Conclusions:

• Graphene films serve as effective artificial solid electrolyte interphases in aqueous lithium systems.
• The G-SEI enhances cycle life and float charge stability by controlling ion diffusion and gas permeation.
• The demonstrated scalability suggests significant potential for manufacturing and commercial application.