Sequential Additive Engineering Enables Uniform Carbon Coating and Enhanced Interfacial Properties in LiFe_1-xMn_xPO₄...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium manganese iron phosphate (LiFe_1-xMn_xPO₄, LMFP) cathodes show promise for batteries but suffer from poor electron transport and unstable interfaces.
• Surface carbon coating is common, but its effectiveness depends on precursor assembly, which is often uncontrolled.

Purpose of the Study:

• To investigate the impact of additive sequence on the interfacial carbon architecture of LMFP cathodes.
• To develop a method for creating high-quality carbon shells to improve electrochemical performance.

Main Methods:

• Synthesizing LMFP cathodes using a novel carbon coating method involving sequential addition of poly(ethylene glycol) (PEG) and glucose.
• Characterizing the carbon shell structure and interfacial properties.
• Evaluating the electrochemical performance (capacity, cycling stability, conductivity, Li+ diffusivity) of the modified cathodes.

Main Results:

• Sequential addition of PEG before glucose formed a coordinated adsorption layer, guiding uniform precursor assembly.
• This resulted in a dense, ordered carbon shell, enhancing interfacial integrity and electronic connectivity.
• The modified LMFP cathodes exhibited a high initial discharge capacity (161 mAh/g at 0.1 C), excellent cycling stability (113 mAh/g at 1 C after 400 cycles), and significantly improved electronic conductivity and Li+ diffusivity.

Conclusions:

• Reaction sequence is a critical, tunable parameter for engineering interfacial carbon structures in LMFP cathodes.
• This generalizable approach can improve surface chemistry and boost performance in various carbon-coated electrode materials.