Synergistic Effect of Anionic-Tuning and Architecture Engineering in BiPO₄@C Anode for Durable and Fast Potassium...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Bismuth-based materials are promising for potassium-ion batteries (KIBs) due to high capacity but suffer from structural degradation and poor conductivity.
• Volume expansion and structural collapse during alloying/dealloying limit the practical application of traditional bismuth anodes in KIBs.

Purpose of the Study:

• To engineer carbon-coated nanosized BiPO₄ rods (BiPO₄@C) to overcome the limitations of bismuth-based anodes in KIBs.
• To improve structural stability, ionic conductivity, and overall electrochemical performance for advanced potassium storage.

Main Methods:

• Fabrication of carbon-coated nanosized BiPO₄ rods using architecture engineering and anionic-tuning strategies.
• Electrochemical characterization including specific capacity, cycling stability, and rate performance testing.
• In-situ/ex-situ X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and kinetic tests to elucidate the reaction mechanism.

Main Results:

• BiPO₄@C nanorods exhibit high specific capacity (310.3 mAh g^-1 at 500 mA g^-1) and excellent cycling stability (over 700 cycles).
• Superior rate performance was achieved, with 137.8 mAh g^-1 at 1000 mA g^-1, demonstrating efficient charge transport.
• Revealed a "conversion-multistep alloying" reaction and "battery-capacitance dual-mode" potassium storage mechanism.

Conclusions:

• The developed BiPO₄@C nanostructure effectively mitigates volume expansion and enhances ionic/electronic conductivity in KIB anodes.
• The anionic-tuning strategy with PO₄^3- promotes the formation of K₃PO₄, improving ionic transport and structural integrity.
• Thick electrodes demonstrated significant potential for next-generation potassium-ion batteries, highlighting practical applicability.