Cation/Anion Co-Doping Enhances Oxygen Redox Reversibility and Structural Stability in Single-Crystal Li-Rich...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Li-rich Mn-based cathode materials (LRMs) offer high energy density for next-generation Lithium-ion batteries.
• LRMs face challenges like voltage decay, poor rate capability, low cyclability, and capacity loss at low temperatures due to oxygen release and structural degradation.

Purpose of the Study:

• To enhance the electrochemical performance of LRMs at both room and low temperatures.
• To improve oxygen redox reversibility and structural stability in LRMs.

Main Methods:

• Co-doping of Al and F into novel single-crystal Li_1.2Mn_0.54Ni_0.13Co_0.13O₂.
• Investigation of oxygen redox couple and manganese electronic structure.

Main Results:

• The Al and F co-doped electrode (LRMAF) retained more lattice oxygen (O²⁻) and Mn⁴⁺ after cycling.
• LRMAF demonstrated high energy density (1185 Wh kg⁻¹), initial discharge capacity (329 mAh g⁻¹ at 0.1C), excellent rate capability (155 mAh g⁻¹ at 5.0C), and 88% capacity retention after 100 cycles.
• Remarkable electrochemical performance was observed at -20 °C.

Conclusions:

• Al and F co-doping effectively promotes oxygen redox reversibility and enhances structural stability in LRMs.
• The combination of single-crystal morphology and cation/anion co-doping leads to superior electrochemical performance across a wide temperature range.