Axially coordinated single-atom interface mitigates isolated K toward highly reversible anode-free K metal batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Potassium (K) metal anodes face challenges in practical anode-free batteries due to uncontrolled solid electrolyte interphase (SEI) evolution and isolated K accumulation.
• Systematic investigations into K stripping behavior and isolated K formation are crucial but lacking.

Purpose of the Study:

• To develop a novel current collector modification for anode-free potassium metal batteries.
• To promote uniform K deposition and reversible K stripping.
• To address SEI instability and isolated K formation.

Main Methods:

• Development of axially coordinated single-atom iron (Fe) anchored on hollow carbon bowls (FeN4O2 moiety).
• Utilizing cryo-transmission electron microscopy (cryo-TEM), X-ray photoelectron spectroscopy (XPS) depth profiling, and theoretical calculations.
• Fabrication and testing of anode-free K metal full cells.

Main Results:

• The FeN4O2 moiety optimized K adsorption/desorption, regulated FSI- decomposition, and suppressed isolated K formation.
• The carbon-bowl scaffold mitigated volumetric strain and preserved interfacial integrity.
• Enhanced deposition uniformity and stripping reversibility were observed.
• The anode-free K metal full cell achieved nearly 100 mAh/g over 200 cycles at 200 mA/g.

Conclusions:

• The developed material provides bidirectional regulation for enhanced K anode performance.
• This approach offers a promising strategy for constructing practical and high-performance anode-free potassium metal batteries.
• The findings rival state-of-the-art counterparts in terms of cycling stability and capacity retention.