Anion-Tailored EDL Induced Triple-Layer SEI on High-Capacity Anodes Enabling Fast-Charging and Durable...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-capacity electrodes suffer from poor cycling stability due to particle fragmentation and continuous solid electrolyte interphase (SEI) formation.
• Developing stable SEI layers is crucial for efficient and long-lasting sodium storage in batteries.

Purpose of the Study:

• To introduce a self-adjusting electrolyte additive for improved SEI formation on high-capacity anodes.
• To achieve stable and fast sodium storage by engineering a novel triple-layer SEI structure.

Main Methods:

• Utilized selenium (Se) as a soluble electrolyte additive to regulate the electric double layer (EDL).
• Investigated the in-situ generation and preferential adsorption of Se_x^2- onto the anode's EDL.
• Analyzed the composition and structure of the resulting triple-layer SEI (Se/inorganic/organic).

Main Results:

• A unique triple-layer SEI (inner: Se; mediate: inorganic; outer: organic) was successfully constructed on FeS₂ anodes.
• The Se-induced SEI significantly reduced electrolyte decomposition and gas evolution.
• The FeS₂ anode demonstrated exceptional cycling stability, retaining 93.1% capacity after 6000 cycles at 10 A g^-1.

Conclusions:

• The anion-tailored EDL approach provides a novel SEI model for stable sodium storage in high-capacity anodes.
• Selenium additives offer a promising strategy for developing advanced battery materials for fast-charging applications.
• The triple-layer SEI formation mechanism is applicable to other high-capacity anodes like SnS₂.