Trinitarian Design of Gradient Artificial Interphase Enables Colossal Granular Li Deposits for Stable Li-Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium-metal batteries (LMBs) face limited cycle life due to unstable solid electrolyte interphase (SEI) and lithium dendrite formation.
• Developing artificial SEI layers is crucial for overcoming these challenges and enabling practical LMB applications.

Purpose of the Study:

• To design and investigate a novel trinitarian gradient interphase for lithium-metal anodes (LMAs).
• To enhance the stability and cycling performance of LMBs by suppressing dendrite growth and improving ion flux.

Main Methods:

• Fabrication of a composite coating comprising magnesium fluoride (MgF2), N-hexadecyltrimethylammonium chloride (CTAC), and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) on LMAs.
• Characterization of the SEI composition, morphology, and electrochemical properties.
• Testing the performance of the modified LMAs in Li||LFP, Li||NCM811, and Li||S full cells.

Main Results:

• The MgF2/CTAC/PVDF-HFP coating formed a LiF-rich SEI and a lithiophilic Li-Mg alloy substrate.
• The Li-Mg alloy homogenized electric field distribution and reduced internal resistance.
• The LiF/PVDF-HFP SEI provided fast ion conduction and mechanical flexibility, while CTAC mitigated dendrites via electrostatic shielding.
• Dendrite-free LMAs with stable cycling performance were achieved in various full cell configurations.

Conclusions:

• The synergistic effect of the trinitarian gradient interphase effectively protects the LMA.
• This artificial SEI design promotes uniform lithium deposition and enhances battery cycle life.
• The study offers a promising strategy for advanced artificial SEI engineering in alkali-metal batteries.