From Li₂NiO₃ to high-performance LiNiO₂ cathodes for application in Li-ion and all-solid-state batteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Lithium nickel oxide (LiNiO₂) synthesis often results in Ni_Li point defects due to Ni(II) oxidation to Ni(III).
• Point defects in cathode materials can negatively impact battery performance and longevity.

Purpose of the Study:

• To develop a novel synthesis route for low-defect LiNiO₂.
• To investigate the self-coating effect of Li₂O byproduct on LiNiO₂ particles.
• To correlate residual lithium content with cycling performance in thiophosphate-based solid-state batteries.

Main Methods:

• Conversion of overlithiated Li_1+xNi_1-xO₂ (0 ≤ x ≤ 1/3) materials containing Ni(IV) into LiNiO₂.
• High-temperature synthesis to produce coarse-grained particles.
• Analysis of self-coating effect and residual lithium content.

Main Results:

• Successfully synthesized low defect-density LiNiO₂ samples at high temperatures.
• Observed natural self-coating of LiNiO₂ particles with byproduct Li₂O.
• Established a direct correlation between residual lithium content and cycling performance in solid-state batteries.

Conclusions:

• The conversion of Ni(IV) materials offers an effective method for producing high-quality LiNiO₂ with reduced defects.
• The self-coating of Li₂O byproduct plays a crucial role in enhancing the cycling stability of LiNiO₂ in thiophosphate solid-state batteries.