Unlocking Deep and Fast Potassium-Ion Storage through Phosphorus Heterostructure

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Potassium-ion batteries (KIBs) are a sustainable alternative to lithium-ion batteries for grid-scale storage.
• Elemental phosphorus (P) offers high theoretical capacity but suffers from sluggish kinetics, limiting performance.
• The slow potassiation of P hinders the formation of the final K3P product, impacting reversible capacity and rate capability.

Purpose of the Study:

• To improve the kinetics of elemental phosphorus anodes in KIBs.
• To enable the reversible formation of K3P as the final potassiation product.
• To enhance the overall performance of phosphorus-based KIB anodes.

Main Methods:

• Rational design of black/red phosphorus heterostructures.
• Density functional theory (DFT) calculations to investigate K-ion adsorption and diffusion.
• Electrochemical testing to evaluate capacity, rate capability, and cycling performance.

Main Results:

• The black/red P heterostructure significantly improved K-ion adsorption, injection, and immigration.
• DFT calculations confirmed fast K-ion kinetics at the heterostructure interface.
• Achieved a reversible specific capacity of 923 mAh g⁻¹ at 0.05 A g⁻¹, with 335 mAh g⁻¹ at 1 A g⁻¹.
• Demonstrated excellent cycling stability with 83.3% capacity retention after 300 cycles at 0.8 A g⁻¹.

Conclusions:

• The rational design of black/red P heterostructures successfully unlocks K3P as a reversible potassiation product for elemental P anodes.
• This approach significantly enhances KIB performance, offering a pathway for sustainable and high-performing energy storage.
• The findings provide a strategy to overcome limitations in other sluggish and irreversible battery chemistries.