High-Electron-Insulating Li₂O-Assisted Li₃N for Highly Stable SEI Formation in High-Performance Li-S Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium metal anodes are crucial for high-energy-density batteries but suffer from dendrite formation and interfacial instability.
• The solid electrolyte interphase (SEI) plays a critical role in regulating ion transport and preventing side reactions.
• Optimizing SEI composition to enhance Li+ conductivity while suppressing electron conduction is key to stable lithium metal anodes.

Purpose of the Study:

• To develop an interwoven SEI architecture for lithium metal anodes using in situ coconstruction of Li3N and Li2O.
• To investigate the formation mechanism and electrochemical properties of the modified lithium anode.
• To improve the cycling stability and electrochemical performance of lithium metal batteries.

Main Methods:

• In situ coconstruction of Li3N and Li2O within the SEI using 3-nitro-1,2,4-triazole as a precursor.
• Density functional theory (DFT) calculations to guide material design.
• In situ Raman spectroscopy to elucidate the SEI formation mechanism.
• Electrochemical characterization using symmetric Li||Li cells.

Main Results:

• The Li3N/Li2O-modified anode exhibited a significantly enhanced Li+ transference number (0.403) compared to bare Li (0.234).
• Interfacial charge-transfer resistance was reduced to 53.85 Ω, lower than Li3N-Li (77.73 Ω) and bare Li (94.69 Ω).
• Li||Li symmetric cells demonstrated an extended cycling lifetime of 800 h at 0.5 mA cm-2, over 11 times longer than bare Li.

Conclusions:

• The interwoven Li3N/Li2O SEI architecture effectively enhances Li+ transport and suppresses electron conduction.
• The modified lithium anode exhibits superior interfacial stability and electrochemical performance.
• This strategy offers a promising pathway for developing high-performance and long-lasting lithium metal batteries.