Designable ultra-smooth ultra-thin solid-electrolyte interphases of three alkali metal anodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Dendrite growth in alkali metal anodes severely limits battery lifespan during charge/discharge cycles.
• Achieving stable and long-lasting alkali metal batteries requires effective suppression of dendrite formation.

Purpose of the Study:

• To develop near-perfect alkali metal anodes (lithium, sodium, potassium) with enhanced cycling stability.
• To investigate the role of ultra-smooth, ultra-thin solid-electrolyte interphase (SEI) layers in preventing dendrite growth.

Main Methods:

• Electrochemical polishing to create defect-free metal anode surfaces.
• Atomic Force Microscopy (AFM) force probing for surface characterization.
• X-ray Photoelectron Spectroscopy (XPS) for in-depth analysis of SEI layers.

Main Results:

• Electrochemical polishing resulted in ultra-smooth, ultra-thin SEI layers on lithium, sodium, and potassium anodes.
• The SEI layer exhibited a multi-layered structure with coupled rigidity and elasticity.
• Lithium anodes demonstrated over 200 cycles at 2 mA/cm² with 100% depth of discharge, showing significantly improved stability.

Conclusions:

• An ultra-smooth, ultra-thin SEI layer is crucial for suppressing dendrite growth in alkali metal anodes.
• Electrochemical polishing provides a viable method for creating robust SEI layers, enhancing battery performance.
• This approach offers a promising initial protection strategy for next-generation high-energy-density batteries.