Enhancing Li-Ion Transport in Solid Electrolytes by Confined Water

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Developing high-performance solid-state lithium-ion batteries requires advanced solid electrolytes with fast ion transport and electrochemical stability.
• Hydrate materials, though common, are underutilized as solid electrolytes due to concerns about water limiting electrochemical stability.

Purpose of the Study:

• To investigate the potential of confined water in hydrate materials to enhance lithium-ion transport without compromising electrochemical stability.
• To demonstrate the viability of Li-H-Ti-O quaternary compounds as novel solid electrolytes for solid-state lithium-ion batteries.

Main Methods:

• Synthesis of three Li-H-Ti-O quaternary compounds with varying amounts of confined water.
• Comparative analysis of ionic conductivity and electrochemical stability of the synthesized compounds.
• Fabrication and testing of a solid-state battery utilizing the most promising compound as the solid electrolyte.

Main Results:

• The Li-H-Ti-O compound with structural pseudo-water exhibited ionic conductivity 2-3 orders of magnitude higher than water-free Li4Ti5O12.
• The enhanced ionic conductivity was achieved with a comparable electrochemical stability window.
• The fabricated solid-state battery demonstrated good rate and cycling performance.

Conclusions:

• Confined water can significantly enhance Li-ion transport in solid electrolytes, challenging the notion that water compromises stability.
• Li-H-Ti-O quaternary compounds represent a promising new class of solid electrolytes for solid-state lithium-ion batteries.
• Confinement of water within solid crystal structures offers new design strategies for advanced ceramic materials in various engineering fields.