Defining an Optimal Boron-Doping Window to Navigate the Trade-Off between Li-Ion Kinetics and Interfacial Stability...

Area of Science:

• Materials Science
• Electrochemistry
• Surface Engineering

Background:

• Lithium manganese iron phosphate (LMFP) cathodes offer high operating voltages but suffer from poor kinetics and interfacial instability.
• Sluggish electron/lithium-ion transport and manganese dissolution limit LMFP cathode performance in batteries.

Purpose of the Study:

• To improve the interfacial kinetics and cycling stability of LMFP cathodes.
• To investigate the effect of boron-doped carbon coatings on LMFP performance.
• To determine an optimal boron-doping window for enhanced battery applications.

Main Methods:

• Surface engineering of LMFP cathodes with boron-doped carbon coatings.
• In situ electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis.
• Cyclability and rate performance testing of coated and pristine LMFP samples.

Main Results:

• The 2% boron-doped LMFP cathode retained 95.66% capacity after 100 cycles at 1 C and 93.20% after 300 cycles at 5 C.
• Boron doping facilitated Li-ion migration by modifying electronic structure and creating defects.
• Coated cathodes showed significantly reduced interfacial charge-transfer resistance compared to pristine samples.

Conclusions:

• Boron-doped carbon coatings effectively enhance LMFP cathode interfacial kinetics and stability.
• An optimal boron-doping window was identified for balancing rate performance and cyclability.
• This surface engineering approach offers a viable strategy for developing high-performance olivine cathodes.