Diffusion Along Dislocations Mitigates Self-Limiting Na Diffusion in Crystalline Sn

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Physics

Background:

• Alloying anodes in batteries face self-limiting diffusion (SLD) due to compressive stresses, hindering ion penetration and limiting performance.
• SLD reduces battery rate capability and prevents full anode material usage.
• Tensile residual stresses at the interface can mitigate SLD, improving battery performance.

Purpose of the Study:

• To compare Li-Si and Na-Sn systems to understand how diffusion kinetics influence SLD and battery rate performance.
• To elucidate the mechanisms behind SLD mitigation in specific anode systems.

Main Methods:

• Comparative experimental study of lithium-silicon (Li-Si) and sodium-tin (Na-Sn) systems.
• Analysis of stress evolution and diffusion mechanisms at the anode-electrolyte interface.

Main Results:

• Sodium diffusion into tin (Sn) crystals induces tensile stresses near the interface.
• Tensile stresses promote high-density dislocation nucleation, facilitating dislocation pipe diffusion.
• Dislocations alleviate SLD, enabling ultrafast sodium diffusion rates in crystalline Sn anodes.

Conclusions:

• Understanding diffusion kinetics and stress evolution is crucial for mitigating SLD in alloying anodes.
• Crystalline Sn is a promising anode material for fast-charging batteries due to alleviated SLD.
• This study provides guidelines for selecting anode materials with enhanced rate performance and energy capacity.