Boosting the Ultrastable High-Na-Content P2-type Layered Cathode Materials with Zero-Strain Cation Storage via a...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• P2-type layered transition-metal (TM) oxides (NaTMO₂) are promising cathode materials for sodium-ion batteries (SIBs) due to their high rate capability and cost-effectiveness.
• However, inherent issues like Na⁺/vacancy ordering and multiple phase transitions during cycling lead to poor voltage stability in P2-NaTMO₂.

Purpose of the Study:

• To enhance the structural stability and electrochemical performance of P2-type layered oxides for SIBs.
• To investigate the effects of high Na content and Li dual-site substitution on cathode material properties.

Main Methods:

• Synthesized a novel P2-type layered oxide Na_0.80Li_0.024[Li_0.065Ni_0.22Mn_0.66]O₂.
• Employed high Na content and Li dual-site substitution strategies.
• Characterized structural stability, Na-ion storage capability, and electrochemical performance using various techniques.

Main Results:

• The combined strategies facilitated Mn oxidation to a higher valence state, improving the local environment of TM and Na ions.
• Achieved nearly zero-strain (ΔV = 0.7%) operation and a solid-solution reaction during cycling.
• Demonstrated exceptional rate performance (87% retention at 10 C vs. 0.1 C) and ultrastable cycling (73% retention at 2 C after 1000 cycles).

Conclusions:

• High Na content and Li dual-site substitution effectively enhance structural stability and Na-ion storage in P2-type cathodes.
• The developed material exhibits promising potential for high-performance and long-lasting sodium-ion batteries.
• Provides insights into the electronic and structural chemistry for designing ultrastable cathode materials with zero-strain Na-ion storage.