High-Energy-Density and Long-Lifetime Lithium-Ion Battery Enabled by a Stabilized Li₂O₂ Cathode Prelithiation...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-ion batteries (LIBs) face capacity loss due to lithium consumption during solid electrolyte interface (SEI) formation.
• Cathode prelithiation using additives is a promising strategy to mitigate irreversible capacity loss.
• Lithium peroxide (Li₂O₂) offers high theoretical capacity but suffers from poor ambient stability, hindering its use as a prelithiation additive.

Purpose of the Study:

• To develop a surface protection strategy for ambient processing of Li₂O₂ as a cathode prelithiation additive.
• To investigate the impact of protected Li₂O₂ on the electrochemical performance of LIBs.
• To provide guidance for optimizing prelithiation in LIBs for enhanced energy density and cycle life.

Main Methods:

• Electrospinning of poly(methyl methacrylate) (PMMA) nanofibers to encapsulate Li₂O₂, creating P-Li₂O₂ with enhanced ambient stability.
• Incorporation of P-Li₂O₂ into LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) cathodes (NCM-P-Li₂O₂).
• Fabrication and electrochemical testing of full LIB cells using NCM-P-Li₂O₂ cathodes and Si/Graphite anodes.

Main Results:

• PMMA nanofibers effectively confined Li₂O₂, significantly improving its ambient stability.
• PMMA nanofibers remained stable during cathode slurry processing and dissolved in electrolyte, exposing Li₂O₂ for electrochemical oxidation.
• Optimized prelithiation levels in NCM-P-Li₂O₂ cathodes led to improved cell lifetime and energy density in full cells.

Conclusions:

• Surface protection of Li₂O₂ via PMMA nanofibers is a viable strategy for ambient processing and effective prelithiation in LIBs.
• This approach enhances the electrochemical performance of LIBs, addressing irreversible capacity loss.
• The study offers a pathway for optimizing cathode additives to boost LIB energy density and cycle life.