Garnet/polymer solid electrolytes for high-performance solid-state lithium metal batteries: The role of amorphous...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state electrolytes are crucial for lithium battery safety but suffer from low ionic conductivity and lithium dendrite formation.
• Garnet-type Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) is a promising filler for solid polymer electrolytes, yet interfacial resistance remains a challenge.
• Improving interfacial contact and ion transport is key to advancing solid-state lithium metal battery performance.

Purpose of the Study:

• To enhance the performance of solid composite polymer electrolytes (SCPEs) for solid-state lithium metal batteries (SS-LMBs).
• To address the limitations of LLZTO fillers, specifically their large interfacial resistance and impact on ionic conductivity.
• To develop a stable and efficient electrolyte capable of suppressing lithium dendrite growth.

Main Methods:

• Embedding amorphous Li₂O₂ (LO) into LLZTO particles via a quenching process to create LLZTO@LO.
• Fabricating a solid composite polymer electrolyte (SCPE) using PEO with the modified LLZTO@LO filler.
• Evaluating the ionic conductivity, interfacial stability, and cycling performance of the SCPE in Li│SCPE│Li symmetric cells and LiFePO₄//Li full batteries.

Main Results:

• The LLZTO@LO particles formed a stable interfacial layer of amorphous Li₂O₂, promoting Li⁺ ion transference.
• The PEO/10LLZTO@2LO SCPE achieved a high ionic conductivity of 3.2 × 10^-4 S cm^-1 at 40 °C.
• The Li│(PEO/10LLZTO@2LO) │Li symmetric cell demonstrated stable cycling for 1100 hours, and a LiFePO₄//Li full battery showed stable performance for 400 cycles.

Conclusions:

• The developed LLZTO@LO composite effectively enhances interfacial contact and suppresses lithium dendrite growth in SCPEs.
• The PEO/10LLZTO@2LO SCPE exhibits superior ionic conductivity and long-term stability compared to pristine LLZTO-based electrolytes.
• This work represents a significant advancement towards the practical application of solid-state lithium metal batteries.