A Dendrite-Resistant Sodium/Porous-Carbon Anode for Solid-State Batteries: Strategies and Challenges for Low-Pressure...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium solid-state batteries (Na-SSBs) offer a promising alternative to lithium-ion batteries due to sodium's abundance.
• However, Na-SSBs often fail under practical conditions due to dendrite formation, necessitating high stack pressures.
• Developing stable sodium metal anodes for Na-SSBs at mild conditions is crucial for practical applications.

Purpose of the Study:

• To investigate the use of a porous carbon interfacial layer to enable stable sodium cycling in Na-SSBs at milder pressures.
• To understand the interfacial evolution between the sodium metal anode, porous carbon layer, and solid electrolyte.
• To demonstrate the performance of a quasi-solid-state full cell utilizing this interface.

Main Methods:

• Symmetric cell testing of sodium metal anodes with a porous carbon interface on Na-β″-Al2O3 solid electrolytes (BASE).
• Evaluation of cycling performance at various current densities and temperatures (25 °C and 60 °C).
• Cryogenic ion milling and cross-sectional imaging to analyze interfacial changes.

Main Results:

• Stable sodium cycling achieved in symmetric cells up to 10 mA cm⁻² at 25 °C and 1 mAh cm⁻² at 1 mA cm⁻² and 60 °C.
• Interfacial analysis revealed void formation, sodium extraction, and delamination depending on conditions, yet dendrite resistance was maintained.
• A quasi-solid-state full cell demonstrated an areal capacity of ~2.7 mAh cm⁻² at 0.125 mA cm⁻².

Conclusions:

• The porous carbon interfacial layer effectively enables stable sodium metal cycling in Na-SSBs under milder pressures.
• Understanding interfacial evolution is key to optimizing performance and longevity.
• This approach presents a viable strategy for developing practical Na-SSBs without excessive stack pressure.