Imaging dendrite growth in solid-state sodium batteries using fluorescence tomography technology

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Dendrite formation in solid-state sodium batteries (SSBs) significantly hinders battery efficiency and lifespan.
• Understanding dendrite growth mechanisms is crucial for developing stable and high-performance SSBs.

Purpose of the Study:

• To develop a 3D imaging technique for visualizing sodium dendrite growth in SSBs.
• To investigate the evolution of dendrites during battery cycling.
• To enhance the cycling stability of SSBs through material design.

Main Methods:

• Designed a fluorescent Eu³⁺-doped Na₃Zr₂Si₂PO₁₂ solid electrolyte (SE).
• Utilized fluorescence tomography (FT) with confocal laser scanning microscopy for 3D imaging.
• Performed charge/discharge cycling tests at 25°C.

Main Results:

• Observed the formation of small sodium islands, evolving into large dendrites (tens of micrometers).
• Identified critical dendrite volumes leading to short circuits or performance degradation.
• Achieved over 1 year (487.5 days) of stable sodium plating/stripping cycling by regulating Eu³⁺ doping.

Conclusions:

• The developed FT method provides unprecedented 3D insights into sodium dendrite growth in SSBs.
• Eu³⁺ doping in SEs is a viable strategy to significantly improve cycling stability.
• This work paves the way for designing advanced solid electrolytes for high-performance SSBs.