Designing a Silicon/Iron Selenide Heterojunction as Liquid and All-Solid-State Lithium-Ion Battery Anodes Displaying...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon anodes offer high capacity for lithium-ion batteries but suffer from volume expansion and poor interfacial stability.
• Conventional coatings on silicon anodes show limited adhesion, causing performance degradation and inefficient ion/electron transport.

Purpose of the Study:

• To develop a stable and efficient silicon anode for lithium-ion batteries using a heterojunction strategy.
• To enhance ion and electron transport while mitigating volume expansion issues in silicon anodes.

Main Methods:

• Fabrication of a Si@FeSe@C heterojunction anode with robust Fe-Se-Si bonding and carbon coating.
• Electrochemical testing of anode performance in full cells with liquid and solid-state electrolytes.
• In situ X-ray diffraction, in situ Raman spectroscopy, and density functional theory (DFT) calculations to analyze structural and electrochemical properties.

Main Results:

• The Si@FeSe@C anode achieved a capacity of 1092.8 mAh g⁻¹ after 100 cycles at 0.2 A g⁻¹.
• Maintained over 99.6% Coulombic efficiency for 500 cycles at 1.0 A g⁻¹.
• Demonstrated excellent cycling performance in both liquid and all-solid-state full cells, with DFT confirming reduced Li⁺ diffusion energy barriers.

Conclusions:

• The heterojunction design in Si@FeSe@C anodes significantly improves structural stability and electrochemical performance.
• This approach offers a viable strategy for developing high-performance secondary battery systems.
• The robust interfacial bonding and efficient transport characteristics are key to enhanced battery longevity and capacity.