Electrolyte Design Enabling a High-Safety and High-Performance Si Anode with a Tailored Electrode-Electrolyte...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Silicon anodes offer high capacity for lithium-ion batteries but suffer from poor cyclability due to volume expansion and solid-electrolyte interphase (SEI) instability.
• Traditional carbonate electrolytes exacerbate SEI degradation, limiting silicon anode performance.

Purpose of the Study:

• To improve the cyclability and stability of silicon anodes in lithium-ion batteries.
• To investigate the use of a nonflammable ether-based electrolyte with dual additives for enhanced performance.

Main Methods:

• Utilized a nonflammable ether-based electrolyte with fluoroethylene carbonate and lithium oxalyldifluoroborate dual additives.
• Investigated the formation of a robust SEI layer rich in fluoride (F) and boron (B) species.
• Tested Si/Li cells and full cells with commercial cathodes (LiFePO4 and LiNi0.5Mn0.3Co0.2O2).

Main Results:

• Achieved a high initial Coulombic efficiency of 90.2% in Si/Li cells.
• Demonstrated a low capacity-fading rate of 0.0615% per cycle, retaining 2041.9 mAh g-1 after 200 cycles.
• Full cells showed extended service life: 150 cycles with LiFePO4 and 60 cycles with LiNi0.5Mn0.3Co0.2O2 cathodes.

Conclusions:

• A nonflammable ether-based electrolyte with dual additives effectively regulates the Si/electrolyte interphase.
• This approach leads to superior cyclability and extended cycle life for silicon anodes in lithium-ion batteries.
• Offers a scalable strategy for developing high-performance silicon-based batteries.