Modification of the Ni-Rich Layered Cathode Material by Hf Addition: Synergistic Microstructural Engineering and...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Ni-rich layered oxide cathode materials, such as lithium nickel cobalt aluminum oxide (LiNiCoAl_1-O₂), are crucial for high-energy lithium-ion batteries.
• However, their practical application is hindered by rapid capacity decline due to microcracks and surface degradation during cycling.

Purpose of the Study:

• To improve the electrochemical performance and cycling stability of Ni-rich LiNi_0.9Co_0.08Al_0.02O₂ (NCA90) cathode materials.
• To investigate the effects of hafnium (Hf) doping on the microstructure and crystal structure of NCA90.

Main Methods:

• A hafnium (Hf) doping strategy was employed to synthesize LiNi_0.895Co_0.08Al_0.02Hf_0.005O₂ (NCA90-Hf0.5).
• Microstructural analysis was performed to observe changes in particle morphology and arrangement.
• Electrochemical cycling tests were conducted to evaluate capacity retention and stability.

Main Results:

• Hf-doping refined primary particles into short rods, increasing secondary particle toughness and reducing porosity.
• The Hf-doped material exhibited a stabilized layered structure with suppressed side reactions due to robust Hf-O bonding.
• NCA90-Hf0.5 demonstrated a superior reversible capacity retention of 95.3% after 100 cycles at 1 C, compared to 82.0% for pristine NCA90.

Conclusions:

• Hf-doping is an effective strategy for microstructural engineering and crystal structure enhancement in Ni-rich layered cathodes.
• This approach significantly improves cycling stability and mitigates capacity fading, paving the way for advanced lithium-ion batteries.