Brief description of several inorganic ceramic solid electrolytes

Inorganic solid electrolyte has the advantages of non-flammability, wide electrochemical stability window, and large shear modulus. And compared with organic electrolyte, it is safer and has a longer service life. Among various solid electrolytes, inorganic ceramic electrolytes such as garnet, sulfide and NASICON type have attracted much attention.

Garnet type solid electrolyte

The garnet-type solid electrolyte LLZO has the advantages of high ionic conductivity, high stability to Li, high energy density, wide electrochemical window and inhibition of Li dendritic growth. However, compared with other types of solid electrolytes, garnet solid electrolytes are prone to form Li₂CO₃ and LiOH at the interface, resulting in the disadvantage of excessive interface contact resistance.

Currently, garnet solid electrolyte interface modification methods are mainly used to improve the interface performance and reduce the solid-solid interface contact resistance, or ion doping treatment of LLZO to improve the electrochemical performance of the LLZO electrolyte sheet and the stability of the cubic phase at room temperature.

Sulfide solid electrolyte

Sulfide solid electrolyte has high ionic conductivity (0.1-1.0 MS / cm) and wide electrochemical window (> 5.0 V) at room temperature vs.Li/Li +However, due to its extreme sensitivity to oxygen and moisture, it has the disadvantages of poor electrochemical stability and poor air stability.

At present, the air stability of sulfide solid electrolyte materials is improved by substituting or doping oxides Li₂O, P₂O₅, ZnO, Fe₂O₃, Bi₂O₃ and halide LII.

NASICON solid electrolyte

NASICON-type solid electrolyte (LATP) can conduct not only sodium ions, but also lithium ions. This type of electrolyte has high ionic conductivity (close to 1mScm^-1 at room temperature), low density (~2.9g/cm³), and can be used in water and air. It has excellent stability (due to the strong PO bond in the LATP structure) and other advantages. However, when it is in contact with the lithium metal negative electrode, Ti⁴⁺ is easily reduced to Ti³⁺, making the electrolyte material unstable.

In summary, the currently commonly used inorganic ceramic solid electrolytes have relative limitations. However, in recent years, researchers have done a lot of research on key materials of solid electrolytes, by improving the preparation process and modifying the solid electrolyte materials. , A series of inorganic composite solid electrolytes that take into account mechanical properties, ionic conductivity, electrochemical window and stability have been continuously developed, which will help realize the wide application of all-solid-state lithium batteries.