A Brief Introduction to Solid-State Electrolyte

With the evolution of solid-state lithium batteries from concept to actual products, the technology has also gradually matured. However, there is still a long way to go before achieving large-scale commercialization. The key distinction of solid-state batteries is the use of solid-state electrolytes, unlike the liquid electrolytes in conventional lithium-ion batteries.

Ideally, solid-state electrolytes need to demonstrate both high ionic conductivity and low electronic conductivity. In general, they can be categorized into inorganic, polymer and composite solid state electrolytes.

Inorganic solid state electrolytes are typical all-solid state electrolytes, free of liquid components and exhibiting excellent thermal stability, which fundamentally resolves the safety issues. They possess good processability and can be produced at nanometer-scale thickness, commonly applied in thin film batteries. Structurally, they include NASICON, LISICON and ABO3 perovskite structures.

Solid state electrolytes demonstrate properties like high ionic conductivity, wide electrochemical stability window, ease of film formation, and hold vast application potential. However, oxides have higher stability but lower conductivity, while sulfides show the opposite trend, needing enhancement.

Solid polymer electrolytes composed of lithium salts and polymers can be classified into all-solid-state and gel systems. The polymer lithium batteries discussed today adopt gel polymer electrolytes for their high energy density and safety. But the room temperature conductivity is generally low due to the polymer matrices.

Inorganic-organic composite solid-state electrolytes refer to electrolytes formed by incorporating inorganic fillers into polymer electrolytes. An appropriate amount of active fillers can significantly improve the ionic conductivity.

Current research is focused on developing inorganic and composite solid state electrolytes with excellent conductivity. Industry experts predict solid-state batteries to achieve large-scale commercialization after overcoming challenges like interfacial stability. We look forward to solid-state electrolytes opening up a new chapter in the electric vehicle era.