Compositionally Sequenced Interfacial Layers for High-Energy Li-Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium-metal batteries (LMBs) offer high energy density but suffer from poor cycling stability due to issues at the anode interface.
• Developing a stable solid electrolyte interphase (SEI) is crucial for improving the reversibility and longevity of Li-metal anodes.
• Electrolyte additives are key to engineering robust SEI layers that can manage Li deposition and electrolyte degradation.

Purpose of the Study:

• To investigate the role of multifunctional electrolyte additives in engineering a hierarchical SEI for LMBs.
• To understand how the designed SEI structure influences Li+ transport, Li deposition, and electrolyte stability.
• To demonstrate the enhanced cycling performance of LMBs with an optimized SEI layer.

Main Methods:

• Fabrication of multilayered SEI structures using electrolyte additives and fluorinated solvents.
• In-depth analysis of SEI composition and morphology, including LiF-rich, P-O, and polymeric species.
• Electrochemical testing of Li||LiNi0.8Co0.1Mn0.1O2 full cells to evaluate cycling stability and performance.

Main Results:

• An engineered hierarchical SEI comprising LiF-rich, P-O, and elastic polymeric species was successfully formed.
• The multilayered SEI facilitated homogeneous Li+ supply, non-localized Li deposition, and reduced electrolyte degradation.
• The outer polymeric SEI layer effectively accommodated anode volume fluctuations, significantly enhancing cycling stability.

Conclusions:

• Electrolyte additives and fluorinated solvents can engineer advanced interfacial layers for LMBs.
• The developed hierarchical SEI promotes stable cycling and high performance in Li-metal anodes.
• This work opens new avenues for high-performance LMB development through electrolyte formulation engineering.