Complex-Concentrated Anion Doping Enables Ultra-Stable Lattice Oxygen and Structural Integrity in Lithium-Rich...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium- and manganese-rich (LMR) layered oxides offer high capacity and energy density for advanced lithium-ion batteries.
• However, LMR cathodes suffer from poor oxygen instability and structural degradation, leading to voltage fade and capacity decay.

Purpose of the Study:

• To enhance the oxygen-redox and structural stability of LMR cathodes.
• To overcome the limitations of intrinsic oxygen instability and structural degradation in LMR materials.

Main Methods:

• Complex-concentrated anion doping using multiple anions (F, Br, S) in the oxygen sublattice.
• Characterization using X-ray absorption spectroscopy and aberration-corrected scanning transmission electron microscopy.
• Electrochemical cycling in a pouch cell configuration.

Main Results:

• Achieved ultra-stable local oxygen coordination environments and inhibited detrimental phase transformations.
• Preserved the LiTM6 transition metal honeycomb ordering after cycling.
• Demonstrated a zero-strain LMR cathode with only 0.63% volume change and ultralow voltage fade (1 mV/cycle).
• Achieved 93% energy retention after 200 cycles.

Conclusions:

• Complex-concentrated anion doping is a broadly applicable strategy for improving chemo-mechanical stability in ceramic intercalation electrodes.
• This approach resolves key failure mechanisms in LMR cathodes, enabling next-generation energy storage.
• The developed LMR cathode exhibits exceptional cycling stability and energy retention.