Transforming Solid-State Garnet Interfaces into High-Performance Oxyhalide Electrolytes through Low-Temperature Processing

초록

Solid-state batteries (SSBs) offer higher energy density and improved safety compared to conventional lithium-ion batteries. Among various solid electrolytes, garnet-type LLZTO (Li?.₄La₃Zr₁.₄Ta?.?O₁₂) stands out due to its wide electrochemical stability and excellent mechanical properties. However, the rigid interface between LLZTO and cathode materials increases interfacial resistance, mainly due to Li₂CO₃ layers and space charge effects, which hinder ion transport and degrade performance. Existing solutions, such as surface modification and high-temperature sintering, partially address these issues but face challenges related to chemical instability and manufacturing complexity. This study introduces a novel gas?solid reaction method to address interfacial challenges. By reacting NbCl? powder with LLZTO under heat treatment in a tube furnace at ~200°C, Li₂CO₃ layers are transformed into a high-voltage-stable oxyhalide electrolyte (Li?Nb?O?Cl). This low-temperature process offers a simplified approach to interfacial modification, reducing process complexity while minimizing elemental diffusion risks and improving compatibility with cell components. Consequently, this method effectively lowers interfacial resistance and enhances ionic transport. This work presents an energy-efficient strategy to enhance interfacial stability, marking a significant advance in next-generation SSB performance and enabling safer, more efficient energy storage solutions.