Overcoming the Interfacial Limitations Imposed by the Solid-Solid Interface in Solid-State Batteries Using Ionic...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Li-garnets are promising solid electrolytes for lithium metal batteries due to their stability.
• Brittleness and stiffness of Li-garnets lead to high interfacial resistance, hindering ionic mobility.
• Poor electrode-electrolyte contact is a major challenge in solid-state batteries.

Purpose of the Study:

• To improve interfacial contact and reduce resistance in Li-garnet solid electrolytes.
• To enhance the electrochemical performance and stability of lithium metal batteries.
• To suppress lithium dendrite growth during battery operation.

Main Methods:

• Utilizing ionic liquid electrolyte (ILE) thin interlayers at electrode/electrolyte interfaces.
• Fabricating and testing symmetric Li/Li cells with ILE modification.
• Assembling and evaluating Li/LLZO/LFP cells in monopolar and bipolar configurations.

Main Results:

• ILE interlayers significantly reduced interfacial resistance at both positive and negative electrodes.
• Homogeneous lithium deposition and suppressed dendrite growth were observed at high current densities (0.3 mA cm⁻²).
• Overpotential in symmetric Li/Li cells decreased from 1.35 V to 0.35 V.
• Bipolar cells achieved high voltage (≈8 V), specific capacity (145 mAh g⁻¹), and coulombic efficiency (>99%).

Conclusions:

• Ionic liquid electrolyte interlayers are effective in overcoming interfacial barriers in Li-garnet solid electrolytes.
• The strategy significantly enhances lithium metal battery performance, stability, and safety.
• ILE modification offers a promising approach for developing high-performance solid-state batteries.