Compositional gradient design and microstructural engineering enable ultra-stable quinary Ni-rich cathodes in...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-voltage nickel-rich cathodes are desirable for high energy density batteries.
• However, high-voltage operation causes strain and surface degradation, limiting cycle life.
• Existing ultrahigh-nickel cathodes face challenges with stability.

Purpose of the Study:

• To develop a stable, high-voltage cathode material with energy density comparable to ultrahigh-nickel counterparts.
• To address strain accumulation and surface degradation issues in high-voltage cathode operation.
• To create a practical synthesis method for gradient cathode materials.

Main Methods:

• In-situ co-precipitation strategy to synthesize a quinary full-concentration-gradient cathode (LiNi0.73Co0.05Mn0.20Al0.01B0.01O2).
• Incorporation of Boron (B) and Aluminum (Al) to mitigate gradient effects and stabilize lattice oxygen.
• Electrochemical testing of the synthesized cathode in pouch-type full cells (2.7-4.5 V).

Main Results:

• The gradient cathode exhibits enhanced surface mechanical strength and stress dissipation.
• Boron and Aluminum incorporation stabilized the lattice oxygen, preventing gas emission and structural distortion.
• Achieved a high capacity of 210.5 mAh g⁻¹ (815.4 Wh kg⁻¹) and 90.1% initial Coulombic efficiency.
• Demonstrated exceptional long-term cyclability, retaining 87.3% capacity after 1700 cycles.

Conclusions:

• The developed gradient cathode design offers a practical approach for high-voltage battery applications.
• This material overcomes key limitations of traditional Ni-rich cathodes, enabling stable high-voltage operation.
• The synthesis strategy provides a pathway for creating advanced cathode materials for next-generation energy storage.