Interface Engineering of Lithium Metal Anodes via a Polysulfide-Phosphosiloxane Additive for Durable Li-S Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur batteries (LSBs) offer high theoretical energy density but suffer from lithium dendrite growth and unstable solid electrolyte interphase (SEI) layers, hindering commercialization.
• Developing stable interfaces for lithium metal anodes is crucial for advancing LSB technology.

Purpose of the Study:

• To introduce a novel electrolyte additive, polyphosphosiloxane polysulfide polymer (LPSP-PDMS), for enhancing lithium metal anode interfaces in LSBs.
• To investigate the in situ formation of a hybrid SEI layer and its impact on dendrite suppression and ion conductivity.

Main Methods:

• Synthesis and characterization of LPSP-PDMS as an electrolyte additive.
• Fabrication and electrochemical testing of lithium symmetrical cells and lithium-sulfur full cells using the additive.
• Analysis of the SEI layer composition and morphology.

Main Results:

• The in situ reaction of LPSP-PDMS forms a hybrid SEI layer comprising inorganic (LiCl, Li-Si-O) and organic components.
• This hybrid SEI acts as a rigid barrier and efficient ion conductor, facilitating dendrite-free lithium deposition.
• Li₃PS_8.5-PDMS demonstrated remarkable stability in a lithium symmetrical cell (1000 h at 1 mA cm^-2, 23 mV overpotential) and improved performance in a full cell (710.5 mA h g^-1 after 300 cycles at 1 C).

Conclusions:

• LPSP-PDMS is an effective electrolyte additive for stabilizing lithium metal anodes in LSBs.
• The formation of a robust hybrid SEI layer is key to achieving dendrite-free lithium deposition and enhanced battery performance.
• This approach offers a promising strategy for designing functional additives for high-performance and safe LSBs.