Influence of Co/Ca Codoping Induced Interlayer Structural Regulation on Sodium Storage of P2-Mn-Fe-Cu-Based Oxide...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• P2-type Mn-Fe-Cu-based materials are promising for sodium-ion batteries (SIBs).
• Challenges include phase transitions, oxygen release, capacity degradation, and poor cycling stability.
• These issues hinder the practical application of these cathode materials.

Purpose of the Study:

• To develop a novel P2-type cathode material with enhanced stability and performance for SIBs.
• To investigate the effects of codoping with Cobalt (Co) and Calcium (Ca) ions.
• To mitigate detrimental phase transitions and oxygen release in Mn-Fe-Cu-based cathodes.

Main Methods:

• Synthesis of a novel P2-Na_0.65Ca_0.05Mn_0.55Co_0.05Fe_0.2Cu_0.2O₂ cathode material via codoping.
• Incorporation of Co³⁺ into Mn sites to mitigate Jahn-Teller distortion and activate anionic redox.
• Substitution of Ca²⁺ into Na sites to enhance Na⁺ pathway stability and suppress layer sliding.

Main Results:

• The codoped material exhibits enhanced Na⁺ diffusion kinetics, improved conductivity, and reduced electrolyte corrosion.
• Demonstrates high initial discharge capacity (125.9 mAh g^-1 at 0.2 C) and excellent rate performance (79.6 mAh g^-1 at 10 C).
• Achieves outstanding long-cycle stability with 73.2% capacity retention after 1000 cycles at 10 C.

Conclusions:

• Co/Ca codoping effectively suppresses phase transitions and oxygen loss in P2-type cathodes.
• The synergistic effects of Co and Ca enhance electrochemical performance and structural stability.
• This codoping strategy offers a promising pathway for developing high-performance SIB cathode materials.