Stabilizing the Interphase in an Ultra-High-Nickel Cathode Enabling High-Performance Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-nickel (Ni ≥ 90%) cathodes offer high specific capacity for next-generation lithium-ion batteries (LIBs).
• Residual lithium compounds on cathode surfaces cause high interfacial reactivity, limiting practical application.
• Developing stable electrode-electrolyte interfaces is crucial for high-nickel cathode performance.

Purpose of the Study:

• To enhance the stability and performance of high-nickel cathodes by addressing interfacial reactivity.
• To investigate a simple surface modification method for LiNi_0.9Co_0.06Mn_0.04O₂ (NCM90) cathodes.
• To improve the cycle life and capacity retention of LIBs utilizing NCM90 cathodes.

Main Methods:

• Surface modification of NCM90 cathode material using sulfur (S).
• Employing a dry mixing and low-temperature heat treatment process.
• Characterization of the modified electrode-electrolyte interface and electrochemical performance evaluation.

Main Results:

• Conversion of surface residual lithium compounds into inactive lithium sulfate (Li₂SO₄).
• Formation of a stable, inorganic-enriched electrode-electrolyte interface.
• Significant enhancement in capacity retention for NCM90/Li and NCM90/graphite cells after prolonged cycling.
• Inhibition of side reactions, lattice collapse, and transition metal ion dissolution.

Conclusions:

• Sulfur surface modification effectively stabilizes high-nickel cathodes by creating a protective interface.
• The developed method offers a feasible approach for improving the performance of next-generation LIBs.
• This work provides a new strategy for designing advanced electrode-electrolyte interfaces for high-nickel cathode materials.