A Self-Assembled Single-Ion Membrane via In Situ Neutralization Enables Triple Stability in Ultrahigh-Nickel Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Ultrahigh-nickel layered oxides (Ni ≥ 90%) provide high specific capacity for lithium-ion batteries (LIBs).
• These materials face significant challenges including poor air stability, low thermal stability, and rapid capacity decay.
• Existing strategies struggle to simultaneously overcome these limitations, hindering commercialization.

Purpose of the Study:

• To develop a novel strategy for simultaneously enhancing the air stability, thermal resistance, and electrochemical performance of ultrahigh-nickel layered oxide cathodes.
• To engineer a self-assembling single-ion conductor membrane for integrated interfacial protection.
• To provide a scalable and industrially viable pathway for advanced LIBs.

Main Methods:

• Rational design and engineering of a self-assembling single-ion conductor membrane with hydrophobicity and thermal stability (>445°C).
• Utilizing the N-cyano-sulfonamide group for in-situ neutralization with residual LiOH/Li2CO3 on LiNi0.9Co0.05Mn0.05O2 (NCM9055) cathodes.
• Formation of a self-assembled protective coating via Donnan exclusion against PF6- anions.

Main Results:

• A self-assembled protective coating was formed on NCM9055, enhancing hydrophobicity and anion exclusion.
• A 3.5 Ah NCM9055/Gr pouch battery exhibited 94.97% capacity retention after 500 cycles.
• The onset temperature of thermal runaway was significantly increased from 124.2°C to 158.2°C.

Conclusions:

• The engineered membrane effectively addresses the critical bottlenecks of ultrahigh-nickel layered oxide cathodes.
• This unified interfacial engineering paradigm offers a scalable solution for safe, long-life, high-energy-density LIBs.
• The study presents a promising pathway for the commercial deployment of advanced battery technologies.