Interlayer Engineering and Prelithiation: Empowering Si Anodes for Low-Pressure-Operating All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Silicon anodes are promising for high-energy all-solid-state batteries (ASSBs) due to the absence of lithium dendrite issues.
• Previous research often used high operating pressures, masking critical electrochemo-mechanical challenges for practical ASSB applications.
• Low-pressure operation is crucial for the real-world viability of silicon-based ASSBs.

Purpose of the Study:

• To overcome the limitations of silicon anodes operating under low pressures in ASSBs.
• To investigate the efficacy of a silver (Ag) interlayer and anode prelithiation for enhancing silicon anode performance.
• To optimize silicon composite electrodes for mechanical stability and electrical conductivity.

Main Methods:

• Fabrication of silicon composite electrodes (Si/polyvinylidene fluoride/carbon nanotubes) with a silver interlayer.
• Introduction of an Ag interlayer between the Li6PS5Cl solid electrolyte and the silicon anode.
• Anode prelithiation using thermal evaporation of lithium metal.
• Performance evaluation under low operating pressure (15 MPa) using operando electrochemical pressiometry and ex situ analyses.

Main Results:

• The Ag interlayer significantly enhances interfacial contacts and battery performance under low pressure (15 MPa), unlike high pressure (70 MPa).
• Ag-coated silicon anodes achieved a higher discharge capacity (2430 mA h g⁻¹) compared to bare silicon anodes (1560 mA h g⁻¹).
• In situ lithiated Ag interlayer provides deformable, adhesive, and protective properties, ensuring robust interfacial contact.
• Prelithiation further improved the cycling stability of the silicon anodes.

Conclusions:

• A silver interlayer is an effective strategy to enable stable and high-performance silicon anodes in all-solid-state batteries under practical low operating pressures.
• The study demonstrates a viable approach to address electrochemo-mechanical challenges in silicon anodes for next-generation ASSBs.
• Optimized interfacial engineering and prelithiation are key for advancing silicon anode technology in ASSBs.