Electrolyte Chemistry Modulation Toward High-Performance and Ultralow-Temperature Silicon Anode

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Silicon anodes offer high capacity but suffer from poor cycle life and low efficiency in conventional electrolytes due to volume expansion and unstable solid electrolyte interphase (SEI).
• Poor electrode kinetics at subzero temperatures limit the practical application of silicon-based batteries.

Purpose of the Study:

• To design a novel electrolyte that enhances the stability and electrochemical kinetics of silicon anodes at both room and ultralow temperatures.
• To overcome the limitations of silicon anodes in terms of capacity decay and low-temperature performance.

Main Methods:

• A rational electrolyte design strategy was employed, combining two ether-based solvents: cyclopentylmethyl ether and tetrahydrofuran.
• The electrolyte was optimized to tune solvation chemistry and interfacial behavior for improved performance.

Main Results:

• The optimized electrolyte facilitated high cation conductivity, a low Li-ion desolvation barrier, and the formation of a robust LiF-elastic polymer SEI.
• Silicon anodes exhibited extended cyclability with over 80% capacity retention after 200 cycles at -20 and -35 °C.
• At -40 °C, the silicon electrode delivered a high reversible capacity of 2157.0 mAh g⁻¹, with 68.5% capacity retention relative to room temperature.
• Full cells (Si||LiFePO₄ and Si||LiNi₀.₈Co₀.₁Mn₀.₁O₂) showed no capacity degradation over 180 and 120 cycles, respectively, at -20 °C.

Conclusions:

• The developed electrolyte significantly enhances the interfacial stability and electrochemical reaction kinetics of silicon anodes.
• This electrolyte design enables high-performance silicon-based batteries that operate effectively across a wide temperature range, including ultralow temperatures.
• The findings pave the way for advanced silicon anode materials in next-generation energy storage devices.