High voltage electrolytes for lithium-ion batteries with micro-sized silicon anodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Micro-sized silicon anodes offer high energy density for lithium-ion batteries but suffer from volume expansion, cracking, and rapid capacity decay due to electrolyte penetration.
• Existing organic-inorganic interphases and silicon particles degrade during cycling, leading to electrode swelling and performance loss.

Purpose of the Study:

• To address the challenges of silicon anode instability in lithium-ion batteries.
• To design a high-voltage electrolyte that forms stable, silicon-phobic interphases.
• To enhance the cycle life and energy density of micro-sized silicon anodes.

Main Methods:

• Design and synthesis of a novel high-voltage electrolyte.
• Fabrication of micro-sized silicon anodes (5 µm) with high loading (4.1 mAh cm⁻²).
• Electrochemical testing of silicon anodes and LiNi₀.₈Co₀.₁₅Al₀.₀₅O₂ pouch full cells.

Main Results:

• The designed electrolyte enabled micro-sized silicon anodes to achieve 99.8% Coulombic efficiency and 2175 mAh g⁻¹ capacity over >250 cycles.
• Full cells demonstrated a high capacity of 172 mAh g⁻¹ over 120 cycles with >99.9% Coulombic efficiency.
• The electrolyte successfully formed silicon-phobic interphases with weak bonding to lithium-silicon alloys, mitigating volume expansion issues.

Conclusions:

• The developed high-voltage electrolyte effectively stabilizes micro-sized silicon anodes by forming silicon-phobic interphases.
• This approach significantly improves cycle life and Coulombic efficiency, overcoming major hurdles for silicon anode commercialization.
• The findings pave the way for next-generation, high-energy-density lithium-ion batteries utilizing micro-sized silicon anodes.