Unique Spindle-Like Bismuth-Based Composite toward Ultrafast Potassium Storage.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Bismuth (Bi)-based materials are promising anodes for potassium ion batteries (PIBs) due to their high theoretical capacity and suitable voltage.
• Developing stable and efficient anodes is crucial for advancing PIBs for practical energy storage applications.

Purpose of the Study:

• To synthesize and characterize a novel spindle-like structured bismuth@nitrogen-doped carbon composite (SPB@NC) for use as an anode in PIBs.
• To investigate the electrochemical performance, potassium storage mechanism, and kinetics of the SPB@NC anode.

Main Methods:

• In-situ carbon thermal reduction method to create interconnected nano-Bi coated with a heteroatom-doped hard carbon layer.
• Electrochemical testing including galvanostatic cycling, rate capability tests, and cyclic voltammetry.
• Ex-situ techniques to analyze the material's structure and composition before and after cycling.

Main Results:

• The SPB@NC composite exhibits a unique porous structure with interconnected Bi nanoparticles and a stable N-doped carbon layer.
• The anode demonstrates high reversible capacity (276.5 mAh g⁻¹ at 30 A g⁻¹) and excellent cycling stability (299.3 mAh g⁻¹ at 5 A g⁻¹ after 2000 cycles).
• A full cell with a potassium vanadate cathode shows potential for practical applications.

Conclusions:

• The SPB@NC composite offers a robust framework for fast and durable potassium storage in PIBs.
• The N-doped carbon layer enhances electrode stability and facilitates rapid ion/electron transfer.
• This study provides valuable insights into Bi-based anodes for high-performance potassium ion batteries.