Stabilizing the electrode-electrolyte interface for high-voltage Li‖LiCoO₂ cells using dual electrolyte additives.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Rechargeable lithium-metal batteries offer high energy density but face challenges like lithium dendrite growth and cathode degradation at high potentials.
• These issues limit the practical application and cycle life of high-performance lithium-metal batteries.

Purpose of the Study:

• To develop an advanced electrolyte system for high-voltage lithium-metal batteries.
• To address the challenges of lithium dendrite formation and cathode degradation using dual electrolyte additives.

Main Methods:

• Formulation of a fluorinated carbonate-based electrolyte with *trans*-4,5-difluoro-1,3-dioxolan-2-one (DFEC) and tri-(trimethylsilyl) phosphite (TMSPi) as dual additives.
• Investigation of the electrolyte's effect on the solid-electrolyte interface (SEI) of the lithium anode and the cathode-electrolyte interface (CEI) of the LiCoO₂ cathode.
• Electrochemical performance testing of Li‖LiCoO₂ cells using the developed electrolyte at a high upper cut-off voltage of 4.6 V.

Main Results:

• DFEC promotes a stable SEI layer on the lithium anode, effectively inhibiting dendrite growth.
• TMSPi facilitates the formation of an inorganic-rich CEI layer on the LiCoO₂ cathode, suppressing cobalt dissolution.
• Li‖LiCoO₂ cells achieved an initial capacity of 211.6 mAh g^-1 and retained 81.6% after 200 cycles at 4.6 V.

Conclusions:

• The proposed electrolyte with DFEC and TMSPi dual additives successfully constructs stable interfaces on both the anode and cathode.
• This advanced electrolyte enables high-voltage operation of Li‖LiCoO₂ batteries with enhanced cycle life and capacity retention.
• The findings offer valuable insights for developing next-generation electrolytes for high-energy and high-voltage lithium-metal batteries.