Stabilizing Lattice Oxygen Redox via Thermally Driven La-Stratification for Ultra-Stable Li-Rich Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium- and manganese-rich layered oxides (LMR) offer high capacity and low cost for advanced lithium-ion batteries.
• Commercialization is hindered by capacity fading and voltage decay due to irreversible lattice-oxygen loss.

Purpose of the Study:

• To develop a surface-bulk co-engineering strategy to mitigate capacity fading and voltage decay in LMR cathodes.
• To improve the electrochemical performance and cycling stability of LMR materials for next-generation batteries.

Main Methods:

• A thermally driven stratification (TDS) strategy was employed to create a La2O3 surface coating and a bulk La concentration gradient.
• Advanced characterization techniques and Density Functional Theory (DFT) calculations were used to analyze structural and chemical changes.
• Electrochemical testing was performed to evaluate the performance of the optimized LMR-TDS cathode.

Main Results:

• The optimized LMR-TDS cathode exhibited a high initial discharge capacity (287.5 mAh g-1) and initial Coulombic efficiency (88.50%).
• The material retained 90.37% of its capacity after 500 cycles and showed minimal voltage decay (0.967 mV/cycle).
• A pouch cell using the LMR-TDS cathode maintained 84.67% capacity after 1000 cycles.

Conclusions:

• The TDS strategy effectively stabilizes the bulk structure and surface chemistry of LMR cathodes.
• Simultaneous surface and bulk modification significantly enhances cycling stability and reduces voltage decay.
• This surface-bulk co-engineering approach presents a viable pathway for developing high-performance LMR cathodes.