Synergistic interface and structural engineering for high initial coulombic efficiency and stable sodium storage in...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Transition metal sulfides (TMS) are promising anode materials for sodium ion batteries (SIBs) due to high capacity and natural abundance.
• Key challenges include large volume changes, unstable solid electrolyte interphase (SEI), and low initial coulombic efficiency (ICE).

Purpose of the Study:

• To develop a novel surface and interface engineering strategy to overcome the limitations of TMS in SIBs.
• To achieve simultaneous long-term cycling stability and high ICE in TMS-based anodes.

Main Methods:

• A "dual-polar confinement" strategy was employed, coating CoS crystals with TiO2 and embedding them in a sulfur-doped carbon matrix (CoS/TiO2-SC).
• An ether-based electrolyte with optimized solvation properties was used to create a stable SEI.
• Advanced characterization and theoretical simulations were utilized to analyze the electrode's properties.

Main Results:

• The CoS/TiO2-SC electrode demonstrated a high ICE of approximately 96%.
• Surface modification facilitated sodium ion transport, mitigated electrode pulverization, and promoted a robust SEI.
• The electrode exhibited high reversible capacity, superior rate capability, and outstanding cycling stability.

Conclusions:

• The dual-polar confinement strategy effectively enhances the electrochemical performance of TMS anodes for SIBs.
• The engineered electrode offers a promising solution for developing stable and efficient sodium ion batteries.