Surface Antisite Defect-Induced Three-Dimensional Li⁺ Diffusion Enables Stable and Kinetic-Enhanced LiFe_1-xMn_xPO₄...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Interfacial degradation is a critical issue for lithium iron manganese phosphate (LMFP) cathodes, hindering their performance.
• Traditional surface modifications create a trade-off between interfacial stability and Li+ transport kinetics.

Purpose of the Study:

• To reconcile interfacial stability and electrochemical kinetics in LMFP cathodes.
• To engineer a novel surface modification strategy for improved cathode performance.

Main Methods:

• Constructing a surface-confined Li-Fe antisite defect layer using ferrocene-assisted thermal treatment.
• Characterizing the antisite defect concentration and its impact on surface structure and ion diffusion.

Main Results:

• Achieved a moderate antisite concentration (∼3.2%) that densifies the surface lattice.
• Significantly suppressed Mn and Fe dissolution, enhancing interfacial stability.
• Enabled a transition of Li+ diffusion from 1D to 3D at the surface, improving kinetics.

Conclusions:

• Controlled antisite engineering reconciles interfacial stability with fast ion transport in phosphate cathodes.
• Antisite defects can be beneficial when properly engineered, challenging conventional views.
• The developed surface modification offers a versatile paradigm for advanced battery materials.