Suppressed Degradation in Semiconducting Lithium-Rich Oxide Cathode Materials via Phase Structure Engineering

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-rich oxides (LROs) offer high discharge capacity (>300 mAh·g⁻¹) for lithium-ion batteries (LIBs) due to anionic oxygen redox.
• Irreversible oxygen redox in LROs causes voltage/capacity degradation and low initial Coulombic efficiency, limiting their practical application.

Purpose of the Study:

• To address the cycling degradation issue in LROs.
• To enhance the electrochemical performance and stability of LRO cathode materials through phase structure engineering.

Main Methods:

• Phase structure engineering (PSE) of Li-rich C2/m and R3̅m phases by modifying transition metal (TM) composition.
• Fabrication of composite-phase LRO nanocrystals (N20, N50, N60, N75, N80) by incorporating various NCM compositions (NCM111, NCM262, NCM523, NCM622, Ni_0.75Co_0.25, NCM811) with Li₂MnO₃.

Main Results:

• The fabricated composite-phase LROs exhibit an increased midpoint voltage (∼3.8 V) and improved cycling stability.
• N75 demonstrated suppressed voltage fade (88.07% retention) with a low fade rate (1.12 mV/cycle).
• N75 achieved 63.68% energy density retention after 400 cycles at 1C (2.0-4.8 V), indicating enhanced long-term stability.

Conclusions:

• Phase structure engineering via TM composition modification is an effective strategy to improve LRO cathode performance.
• The developed composite-phase LROs offer a promising pathway towards high-energy-density and long-lifespan LIBs.
• This research provides valuable insights for designing advanced LRO materials for next-generation energy storage.