Enhancing Cycle Stability in LiNiO₂ with Phase transition suppression via Crystalline Disordered Surface Layer.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Nickel-rich layered oxides are key cathode materials for lithium-ion batteries (LIBs).
• These materials suffer from poor structural stability, limiting their performance and cycle life.
• Current stabilization strategies include doping and surface modification, often used together.

Purpose of the Study:

• To investigate a crystalline disordered surface layer as a stabilization strategy for Ni-rich layered oxides.
• To demonstrate control over the disordered surface layer thickness during synthesis.
• To evaluate the impact of this surface modification on electrochemical performance and stability.

Main Methods:

• Synthesis of single-crystal LiNiO₂ with controlled crystalline disordered surface layers.
• Characterization of the surface layer structure and thickness.
• Electrochemical testing in full cells to assess capacity retention and voltage decay.

Main Results:

• Successfully controlled the thickness of the crystalline disordered surface layer during synthesis.
• Demonstrated that the formation rate of the layered structure dictates the disordered surface layer.
• Achieved 84% capacity retention after 500 cycles with significantly reduced voltage decay.
• A thicker disordered layer led to a slight capacity reduction but enhanced overall stability.

Conclusions:

• A well-controlled crystalline disordered surface layer can effectively suppress structural changes in Ni-rich layered oxides.
• This surface modification provides simultaneous surface protection and mitigation of bulk structural changes.
• The findings offer a new pathway for developing highly stable and durable cathode materials for advanced LIBs.