Si Single-Atom Sites Anchored Carbon Anode Achieving the Zero-Strain Feature and Superior Li⁺ Storage Performance

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Silicon anodes face significant volume expansion challenges, limiting their practical application in lithium-ion batteries.
• The strain in silicon anodes is inversely proportional to their particle size, necessitating strategies to mitigate this effect.

Purpose of the Study:

• To design atomic silicon (Si) sites that exhibit a zero-strain feature, overcoming the volume expansion problem in silicon anodes.
• To investigate the lithium-ion storage mechanism and electrochemical performance of these novel atomic Si sites.

Main Methods:

• Design of atomic Si sites utilizing the ultimate size effect to achieve zero-strain.
• Analysis of the lithium-ion storage mechanism, identifying solid-solution reactions instead of alloying.
• Evaluation of cycling stability and electrochemical reaction kinetics through electrochemical testing.

Main Results:

• Atomic Si sites demonstrated a zero-strain feature due to solid-solution reactions, unlike conventional alloying reactions.
• The ligand structure of atomic Si sites remained stable during cycling, leading to excellent cycling stability.
• Exposed atomic Si sites improved electrochemical kinetics, resulting in outstanding rate performance.
• The anode maintained a low working voltage (~0.21 V) and high specific capacity (~2300 mAh/g).

Conclusions:

• Atomic Si sites offer a novel pathway for designing low/zero-strain anodes for high-performance lithium-ion batteries.
• The solid-solution reaction mechanism and stable ligand structure are key to the observed zero-strain behavior and stability.
• This approach effectively leverages the benefits of silicon anodes while overcoming their primary limitation.