Low-Density Fluorinated Silane Solvent Enhancing Deep Cycle Lithium-Sulfur Batteries' Lifetime

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium metal anode (LMA) instability and high electrolyte demand hinder lithium metal battery development, especially in lithium-sulfur (Li-S) batteries.
• Conventional high-concentration electrolytes stabilize Li metal but increase battery weight due to high density (>1.4 g mL⁻¹).

Purpose of the Study:

• To develop a novel, low-density electrolyte for stabilizing LMAs in Li-S batteries.
• To reduce lithium inventory and electrolyte weight while enhancing battery cycle life.

Main Methods:

• Formulation of a bifunctional fluorinated silane-based electrolyte with a low density (1.0 g mL⁻¹).
• Evaluation of the electrolyte's ability to form a robust solid electrolyte interface (SEI) and minimize lithium depletion.
• Testing of Li-S pouch cells with the proposed electrolyte under limited lithium conditions and a low electrolyte weight/cell capacity (E/C) ratio.

Main Results:

• The proposed electrolyte reduced the Li loss rate by over 4.5-fold compared to conventional electrolytes.
• Li-S pouch cells using the new electrolyte achieved 103 cycles, significantly outperforming cells with conventional electrolyte (38 cycles) at an E/C ratio of 4.5 g Ah⁻¹.
• The electrolyte demonstrated effective stabilization of the LMA and minimized lithium dendrite formation.

Conclusions:

• The developed low-density electrolyte effectively stabilizes lithium metal anodes in Li-S batteries.
• This approach significantly reduces electrolyte weight and lithium inventory, leading to enhanced cyclic stability and longer battery life.
• The findings pave the way for lighter, more efficient, and sustainable lithium-metal batteries.