Stabilization of garnet/Li interphase by diluting the electronic conductor.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• High interfacial resistance and lithium dendrite growth impede solid-state lithium battery (SSLB) performance.
• Limited understanding of electronic conductivity's role in dendrite formation hinders SSLB development.

Purpose of the Study:

• To elucidate the correlation between electronic conductivity, lithium dendrite formation, and interfacial resistance in SSLBs.
• To engineer the interphase of aluminum nitride (AlN) interlayers to control these factors.

Main Methods:

• Diluting electronic conductors within the AlN interlayer during annealing to alter interphase properties.
• Investigating the conversion-alloy reaction between AlN and lithium (Li).
• Characterizing the resulting interphase composition and ionic/electronic conductivity.

Main Results:

• Transformed the interphase from mixed ionic/electronic conductive to solely ionic conductive and from lithiophilic to lithiophobic.
• Formed a compact, lithiophobic, and ionic conductive Li3N layer via Li-Al diffusion.
• Achieved ultrahigh critical current densities of 2.6 mA/cm² (time-constant) and 14.0 mA/cm² (capacity-constant).

Conclusions:

• Demonstrated that controlling interphase nature is crucial for suppressing lithium dendrites and reducing interfacial resistance.
• Provided fundamental insights into the interplay between electronic conductivity and dendrite suppression.
• Established guidelines for designing high-performance SSLBs through tailored interphase engineering.