Ternary Inert Element Co-Doping: a New Approach to Stable 4.7 V LiCoO₂

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium cobalt oxide (LCO) is a key cathode material in portable electronics due to its high energy density.
• Increasing battery voltage for higher capacity is limited by structural degradation in LCO.

Purpose of the Study:

• To develop a strategy for stabilizing LCO structure at elevated voltages.
• To improve the performance and longevity of LCO cathode materials for next-generation batteries.

Main Methods:

• Co-doping LCO with ternary inert elements (Mg and Ni at Li site, Al at Co site).
• Investigating the synergistic effects of Al, Mg, and Ni on structural stability and electrochemical performance.
• Conducting long-term cycling tests at high voltages (4.6 V and 4.7 V).

Main Results:

• Mg and Ni doping stabilize the layered structure in delithiated states and suppress oxygen loss.
• Al doping prevents Co-O octahedra distortion and stabilizes Co layers.
• Co-doping with Al, Mg, and Ni inhibits phase transitions and reduces internal stress, leading to enhanced cycling stability.
• Al-Mg-Ni co-doped LCO achieved 221 mAh g⁻¹ with 65.5% retention after 1500 cycles at 4.6 V.
• At 4.7 V, it delivered 225.8 mAh g⁻¹ with 58.6% retention after 600 cycles.

Conclusions:

• Ternary inert element co-doping is an effective strategy for stabilizing high-voltage LCO.
• This method offers a pathway for improving other layered oxide materials for advanced battery applications.