Dynamic ion-buffering gradient bilayer anode realizes 200 Wh kg^-1 dendrite-free sodium battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium battery development faces challenges from dendrite growth and sodium ion loss in anodes.
• These issues limit the practical application and long-term stability of sodium-ion energy storage systems.

Purpose of the Study:

• To engineer a novel anode material that effectively suppresses dendrite formation and compensates for sodium ion loss.
• To enhance the cyclability and energy density of sodium batteries for practical applications.

Main Methods:

• Fabrication of a gradient sodium-tin alloy/sodium bilayer anode using in situ chemical displacement.
• Characterization of the anode's ion-buffering and ion-reservoir properties.
• Testing of symmetric cells and full cells with a high-loading Na3V2(PO4)3 cathode.

Main Results:

• The gradient alloy phase effectively regulated ion transfer and prevented dendrite growth.
• The metallic sodium layer acted as a dynamic ion reservoir, ensuring structural stability.
• Symmetric cells achieved over 7000 hours of cycling at 3 mA cm-2.
• Full cells demonstrated stable cycling for nearly 1000 cycles with an energy density of 200 Wh kg-1.

Conclusions:

• The engineered sodium-tin alloy/sodium bilayer anode provides a viable solution to critical challenges in sodium battery technology.
• This materials design paradigm paves the way for advanced post-lithium battery systems with superior performance and longevity.