Efficient Li⁺ Transport through a Single-Ion-Conducting Protective Layer for Stable Lithium-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Metallic lithium anodes offer high capacity but suffer from unstable solid electrolyte interphase (SEI), lithium dendrite growth, and side reactions.
• These issues severely limit the cycling performance and safety of lithium-metal batteries.

Purpose of the Study:

• To develop a protective layer that enhances the cycling lifetime and safety of lithium-metal batteries.
• To mitigate common problems associated with metallic lithium anodes.

Main Methods:

• A hybrid single-ion-conducting protective layer (SPL-20) was designed and applied to lithium anodes.
• Electrochemical measurements and simulations were used to evaluate the layer's performance.
• Testing was conducted under various conditions, including extreme temperatures (-25 °C).

Main Results:

• The SPL-20 layer effectively suppressed lithium dendrite formation and surface side reactions.
• Anode-free batteries (LiFePO4/SPL-20@Cu) showed 59% capacity retention after 50 cycles at 0.5 mA cm⁻².
• Full cells (NCM811/SPL-20@Li) demonstrated high specific capacities of 172 mAh g⁻¹ at 25 °C and 143.1 mAh g⁻¹ at -25 °C after 100 cycles.

Conclusions:

• The single-ion-conducting protective layer (SPL-20) significantly improves the stability and safety of lithium-metal batteries.
• This interfacial modification strategy offers a promising solution for overcoming challenges in high-performance lithium-metal battery applications.