Designing a Silicon/Iron Selenide Heterojunction as Liquid and All‐Solid‐State Lithium‐Ion Battery Anodes Displaying Excellent Performances

Why It Matters

The breakthrough addresses silicon anodes’ volume‑expansion problem, paving the way for higher‑energy, longer‑life lithium‑ion batteries across electric vehicles and grid storage.

Key Takeaways

• Heterojunction Si@FeSe@C achieves 1092 mAh g⁻¹ capacity.
• Maintains >99.6% Coulombic efficiency over 500 cycles.
• Works with liquid and all-solid-state electrolytes.
• Fe–Se–Si bonding reduces Li⁺ diffusion barrier.
• In‑situ XRD/Raman confirm reversible phase changes.

Pulse Analysis

Silicon’s theoretical capacity makes it a coveted anode material, yet its >300% volume expansion during lithiation has long limited commercial adoption. Conventional carbon coatings often delaminate, creating high‑impedance interfaces that accelerate capacity fade. By introducing a chemically bonded Fe–Se–Si heterojunction, researchers create a mechanically resilient scaffold that tightly integrates silicon particles while preserving electronic pathways, a strategy that directly tackles the root causes of degradation.

The Si@FeSe@C architecture couples the heterojunction with an outer carbon layer, delivering 1,092.8 mAh g⁻¹ after 100 cycles at modest current and maintaining >99.6% Coulombic efficiency for 500 cycles at higher rates. Density functional theory reveals that the Fe–Se interface lowers the activation energy for Li⁺ migration, while in‑situ XRD and Raman data confirm reversible phase transitions without pulverization. This dual‑phase design simultaneously enhances ion transport and buffers mechanical stress, resulting in a performance envelope that rivals, and in some metrics exceeds, state‑of‑the‑art silicon composites.

Beyond laboratory metrics, the heterojunction anode’s compatibility with both liquid electrolytes and emerging all‑solid‑state electrolytes signals broad market relevance. Solid‑state batteries demand stable, low‑impedance interfaces; the Fe–Se–Si bond provides exactly that, potentially accelerating the rollout of high‑energy density packs for electric vehicles and stationary storage. As manufacturers seek scalable solutions, the heterojunction concept offers a versatile platform that could be adapted to other alloy‑type anodes, fostering a new generation of durable, high‑capacity lithium‑ion technologies.