A synergetic promotion of surface stability for high-voltage LiCoO₂ by multi-element surface doping: a...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• High-voltage lithium cobalt oxide (LiCoO2) is crucial for increasing lithium-ion battery energy density.
• Structural and interfacial degradation, along with safety concerns, limit the use of high-voltage LiCoO2.
• Surface stability is a key challenge for deeply delithiated LiCoO2.

Purpose of the Study:

• To investigate a synergetic strategy for enhancing the surface stability of LiCoO2 at high voltages.
• To study the effects of Ti-Mg-Al co-doping on the LiCoO2 (104) surface.
• To analyze the impact of co-doping on surface stability, electronic structure, and Li+ diffusion.

Main Methods:

• First-principles calculations were employed to study the LiCoO2 (104) surface.
• Systematic investigation of Ti, Mg, and Al dopant effects on surface properties.
• Analysis of electronic structure and Li+ diffusion kinetics.

Main Results:

• Ti, Mg, and Al dopants were successfully introduced into the Co sites of the LiCoO2 (104) surface.
• Co-doping significantly stabilized surface oxygen in the highly delithiated state.
• Aggregating Ti-Mg-Al dopants in the surface layer dramatically suppressed surface oxygen loss.
• Co-doping enhanced electronic conductivity and inhibited charge deficiency of surface oxygen atoms.
• Negligible improvement in surface Li+ diffusion kinetics was observed.

Conclusions:

• Ti-Mg-Al co-doping is a promising strategy to enhance the surface stability of high-voltage LiCoO2.
• Aggregating dopant distribution in the surface layer is key to suppressing oxygen loss.
• Surface-modified LiCoO2 is expected to show improved electrochemical performance at high voltages.
• This approach offers a pathway to overcome limitations in practical energy density for lithium-ion batteries.