A Ceramic Network for Hybrid Solid Electrolyte Lithium Metal Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Hybrid solid electrolytes (HSEs) combine inorganic and organic materials for advanced lithium metal batteries.
• The tortuosity within the polymer phase of HSEs is critical for ion transport and dendrite suppression.
• Current ceramic fillers in HSEs present challenges in understanding ion hopping and optimizing morphology.

Purpose of the Study:

• To investigate an in-plane aligned ceramic fiber network structure for HSEs using Li_6.6La₃Zr_1.6Ta_0.4O₁₂ (Ta-LLZO) fillers.
• To compare the morphological characteristics of this network structure with conventional LLZO fillers.
• To evaluate the impact of tortuosity and network alignment on ionic conductivity, dendrite blocking, and cycling stability.

Main Methods:

• Fabrication of HSEs with an in-plane aligned Ta-LLZO ceramic fiber network.
• Computational simulations to analyze tortuosity and ion transport pathways within the polymer phase.
• Electrochemical testing of symmetric lithium metal cells and full cells with LiFePO₄ cathodes.
• Post-mortem microscopy analysis to confirm dendrite blocking mechanisms.

Main Results:

• The aligned network structure exhibits high tortuosity, effectively blocking lithium dendrite growth.
• Achieved ionic conductivity of 0.44 mS cm^-1 at 60°C with the aligned network HSE.
• Demonstrated long cycling lifetime (>1100 h) in symmetric lithium metal cells at 0.1 mA cm^-2 and 60°C.
• The ceramic network HSE showed superior performance in terms of ionic conductivity, low resistance, and cycling life.

Conclusions:

• The in-plane aligned ceramic fiber network HSE offers a superior morphology for lithium metal batteries.
• Optimizing filler characteristics, particularly tortuosity and alignment, is key to enhancing HSE performance.
• This approach facilitates the development of safer and more durable lithium metal battery technologies.