Boosted Li⁺ transference number enabled via interfacial engineering for dendrite-free lithium metal anodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium metal anodes (LMAs) are crucial for high-energy-density batteries but suffer from dendrite formation, hindering commercialization.
• Dendritic growth leads to short circuits and capacity fading in lithium metal batteries (LMBs).

Purpose of the Study:

• To develop a protective coating for LMAs to suppress dendrite formation and improve the performance of LMBs.
• To enhance the lithium-ion transference number and mitigate electrolyte concentration gradients.

Main Methods:

• Utilized ZIF-67, a metal-organic framework with unsaturated coordinative metal sites, to create a protective layer on Li metal anodes.
• Investigated the immobilization of anions and the creation of ordered ionic diffusion pathways by the ZIF-67 coating.
• Fabricated ZIF-67-Cu@Li symmetric cells and Li-O2 full batteries for performance evaluation.

Main Results:

• The ZIF-67 coating effectively immobilized anions, increasing the lithium-ion transference number (tLi) to 0.57.
• Achieved dendrite-free lithium deposition, leading to stable cycling of ZIF-67-Cu@Li symmetric cells for over 1000 hours.
• Demonstrated a high energy density of 1911.61 W h kg-1 in Li-O2 full batteries utilizing ZIF-67-Cu@Li electrodes.

Conclusions:

• ZIF-67 serves as an effective protective coating for lithium metal anodes, enhancing battery safety and lifespan.
• The developed coating mitigates electrolyte concentration gradients and promotes uniform lithium deposition.
• This approach offers a promising strategy for advancing high-performance lithium metal batteries.