Engineered interfaces between perovskite La_2/3xLi_3xTiO₃ electrolyte and Li metal for solid-state batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Perovskite La_2/3xLi_3xTiO₃ (LLTO) is a promising solid-state electrolyte for lithium metal batteries (LMBs).
• Challenges include high interfacial resistance, dendrite formation, and instability against Li metal, hindering commercialization.
• Dense LLTO pellets with high ionic conductivity were prepared.

Purpose of the Study:

• To investigate the effect of polymer-based interfacial layers on LLTO solid-state electrolytes.
• To address interfacial resistance and dendrite formation in LLTO-based LMBs.
• To improve the electrochemical performance and stability of LLTO electrolytes.

Main Methods:

• Preparation of dense LLTO pellets with enhanced microstructure.
• Coating LLTO pellets with three polymer-based interfacial layers: pure polyethylene oxide (PEO), PEO-LiTFSI (PL), and PEO-LiTFSI-SN (PLS).
• Evaluation of interfacial resistance, ionic conductivity, and performance in symmetric Li cells.

Main Results:

• The PLS gel layer significantly reduced total LLTO resistance to 84.88 Ω cm^-2 but showed inferior performance in Li cells.
• The PL layer effectively reduced lithium nucleation overpotential.
• The PL layer demonstrated stable voltage profiles over 20 cycles without Li dendrite formation.

Conclusions:

• Dense LLTO electrolytes combined with polymeric interfaces can reduce interfacial resistance.
• Polymeric interfaces, particularly the PL layer, improve chemical stability against Li metal.
• LLTO electrolytes with optimized microstructures and interfacial engineering show potential for advanced LMBs.