Mixed Ion/Electron Conductive Li₃N-Mo Interphase Enabling Stable and Ultrahigh-Rate Lithium Metal Anodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium (Li) metal anodes are crucial for high-energy-density batteries but suffer from unstable interfaces and dendrite growth.
• These issues limit the practical application and safety of lithium metal batteries.

Purpose of the Study:

• To design and demonstrate a protective interphase for stabilizing the lithium metal-electrolyte interface.
• To enable dendrite-free and ultrahigh-current-density metallic lithium anodes.

Main Methods:

• A mixed ion/electron conductive Li3N-Mo interphase was synthesized via surface reaction of molten Li and MoN nanosheets.
• Characterization of the interphase's structure, conductivity, and mechanical stability.
• Electrochemical testing of Li3N-Mo/Li anodes in plating/stripping cycles and full cells.

Main Results:

• The Li3N-Mo interphase exhibited high ionic conductivity and mechanical stability, facilitating fast Li-ion diffusion and regulating ion flux.
• Li3N-Mo/Li electrodes showed a stable interface with low overpotential (12 mV) and excellent cyclability (>3200 h).
• Dendrite-free operation was achieved even at high current densities (30 mA cm-2) over 840 h.
• Full cells with LiFePO4 cathodes demonstrated stable cycling (87.9% retention over 200 cycles) and high rate capability (83.7 mAh g-1 at 3C).

Conclusions:

• The Li3N-Mo interphase effectively stabilizes the lithium metal anode, suppressing dendrite growth and enhancing rate capability.
• This strategy offers a viable pathway for developing high-performance, safe lithium metal batteries.