Sub-20 nm Carbon Nanoparticles with Expanded Interlayer Spacing for High-Performance Potassium Storage

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Carbon materials are ideal anodes for potassium-ion batteries (PIBs) due to conductivity and cost, but suffer from volume changes and slow ion diffusion.
• These limitations hinder the practical application of carbon-based materials in high-performance PIBs.

Purpose of the Study:

• To synthesize nitrogen and phosphorus codoped ultrafine carbon nanoparticles (NP-CNPs) as advanced anode materials for PIBs.
• To address the challenges of volume expansion and sluggish kinetics in carbon anodes for potassium-ion batteries.

Main Methods:

• Density functional theory (DFT) guided synthesis of N/P-codoped ultrafine carbon nanoparticles (≤20 nm) via a solvent-free method.
• Electrochemical characterization including cyclic voltammetry, rate capability tests, and long-term cycling.
• In situ Raman spectroscopy and ex situ X-ray diffraction (XRD) to investigate the potassium storage mechanism and volume expansion.

Main Results:

• Synthesized NP-CNPs exhibit expanded interlayer distance, enhanced electrical conductivity, and improved potassium ion adsorption.
• Achieved a high capacity of 270 mA h g⁻¹ at 0.2 A g⁻¹, remarkable rate capability (157 mA h g⁻¹ at 5.0 A g⁻¹), and ultralong cycle life (190 mA h g⁻¹ at 1.0 A g⁻¹ after 4000 cycles with 86.4% retention).
• Demonstrated low volume expansion during cycling, confirming the stability of the NP-CNPs.

Conclusions:

• N/P-codoped ultrafine carbon nanoparticles are a promising high-performance anode material for potassium-ion batteries.
• The developed material overcomes critical limitations of carbon anodes, offering high reversible capacity, excellent rate performance, and long-term cycling stability.
• This work presents a novel strategy for designing advanced carbon nanostructures for energy storage applications.