Electrolyte Engineering for Rejuvenating Inactive Lithium and Constructing High-Performance Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium metal batteries (LMBs) with gel polymer electrolytes offer high energy density and safety.
• Challenges include inactive lithium accumulation and unstable solid-electrolyte interphase (SEI).

Purpose of the Study:

• To address inactive lithium accumulation and SEI instability in LMBs.
• To improve the cycling performance and capacity retention of LMBs.

Main Methods:

• Incorporation of a small amount of iodobenzene as a source of the triiodine/iodine ion (I3-/I-) redox couple.
• Experimental characterization and theoretical analysis to understand the redox couple's function.
• Fabrication and testing of symmetrical Li batteries and NCM811||Li batteries.

Main Results:

• The I3-/I- redox couple actively regenerates lithium and optimizes SEI composition.
• Formation of a robust LiI-endorsed and LiF-rich SEI layer.
• Symmetrical Li batteries achieved 4000 h of cycling at 0.2 mA cm-2.
• NCM811||Li batteries showed 70.31% capacity retention after 720 cycles at 3C and 75.94% after 650 cycles at 4C.

Conclusions:

• Iodobenzene effectively mitigates inactive lithium issues and SEI instability.
• The engineered electrolyte significantly enhances the long-term cycling stability and performance of lithium metal batteries.