Constructing a Stabilized Interface in Ultra-High Nickel Single-Crystal LiNi_0.90Co_0.05Mn_0.05O₂ by a Long-Time...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Nickel-rich layered oxide cathode materials (Ni-rich NCM) are crucial for electric vehicles due to their high capacity and low cost.
• Electrochemical cycling causes phase transitions and lattice distortion in Ni-rich NCM, leading to microcracks and performance degradation.
• The H2-H3 transformation is a key detrimental phase transition affecting Ni-rich NCM stability.

Purpose of the Study:

• To develop an ultra-high nickel cathode material with enhanced stability and cycle performance.
• To investigate the effect of an in situ stable rock-salt layer on Ni-rich NCM.
• To suppress anisotropic lattice distortion and microcrack formation during electrochemical cycling.

Main Methods:

• Synthesis of single-crystal LiNi0.9Co0.05Mn0.05O2 (NCM90-S) with an in situ NiO rock-salt surface layer.
• Electrochemical cycling and performance testing of NCM90-S compared to polycrystalline NCM90-P.
• Analysis of structural stability and capacity retention after prolonged cycling.

Main Results:

• The in situ NiO rock-salt layer effectively protects the cathode material from electrolyte contact.
• Single-crystal NCM90-S, with dispersed primary particles, avoids anisotropic stress changes.
• NCM90-S demonstrated superior capacity retention (80.2% vs. 60.3%) after 300 cycles at 1C compared to NCM90-P.

Conclusions:

• The developed NiO rock-salt surface layer is effective in stabilizing ultra-high nickel cathode materials.
• Single-crystal design combined with the protective layer significantly suppresses microcrack formation and enhances cycle life.
• This approach offers a promising strategy for improving the performance of next-generation batteries for electric vehicles.