A Robust Dual-Layered Solid Electrolyte Interphase Enabled by Cation Specific Adsorption-Induced Built-In...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state lithium metal batteries (SSLMBs) offer high energy density and safety but face challenges from interfacial issues like Li dendrite growth and side reactions.
• These interfacial problems hinder the practical application and long-term stability of SSLMBs.

Purpose of the Study:

• To propose a novel strategy for mitigating interfacial degradation in SSLMBs.
• To enhance the stability and performance of lithium metal anodes by controlling the solid electrolyte interphase (SEI) formation.

Main Methods:

• A cationic built-in electrostatic field was engineered using tributylmethyl-phosphonium bis(trifluoromethanesulfonyl)imide (TMPB) cations.
• The electrostatic field was utilized to drive the formation of an anion-derived, dual-layered SEI on the Li anode.
• The performance of the modified interface was evaluated in Li||Li and Li||LiFePO4 full cells.

Main Results:

• The TMPB cations prevented side reactions between the polyethylene oxide (PEO) electrolyte and the Li anode.
• Anion-derived dual-layered SEI (flexible organic-rich outer layer, Li-ion conductive inorganic-rich inner layer) was successfully generated.
• Li||Li cells showed over 1900 hours of lifespan with reduced polarization; Li||LiFePO4 cells maintained 99.7% efficiency over 200 cycles.

Conclusions:

• The engineered cationic electrostatic field effectively regulates SEI formation, promoting uniform Li deposition and suppressing dendrite growth.
• This approach significantly enhances the cycling stability and lifespan of SSLMBs.
• The findings offer valuable insights for designing advanced solid-state batteries with improved interfacial properties.