Optimized Porous KTi₂(PO₄)₃@N-Doped Carbon Electrode for Enhanced Sodium/Potassium-Storage and Accelerated Activation...

Porous KTi₂(PO₄)₃ nanoparticles are synthesized via a solvothermal method and subsequently modified with nitrogen-doped carbon layers by using polydopamine as the carbon source. The resultant KTi₂(PO₄)₃@N-doped carbon composite (KTP@NC) exhibits a preserved porous structure with abundant pores, facilitating ion diffusion and electrolyte infiltration. Various characterizations, including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy, reveal the successful formation of an interconnected nitrogen-doped carbon network. Theoretical calculations and experimental results demonstrate that the nitrogen-doped carbon layer significantly enhances the electronic conductivity of the material and increases the adsorption energy for the sodium and potassium ions. As an electrode for sodium-ion batteries, the KTP@NC composite shows a reversible capacity of 88.4 mA h g^-1 at 30C and retains 97.3% of its capacity after 400 cycles at 5C, with only 10 activation cycles required. Additionally, it displays outstanding cycle stability at 50 °C. For potassium-ion batteries, the KTP@NC electrode provides a specific capacity of 98.9 mA h g^-1 at 0.5C and maintains 92.9% capacity retention after 150 cycles at 1C. The enhanced electrochemical performance of the KTP@NC electrode can be attributed to the improved reaction kinetics and electronic conductivity enabled by the nitrogen-doped carbon coating.