Structural Modulation of Cu-Mn-Fe Prussian Blue Analogs for Practical Sodium Ion Cylinder Cells

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Grid-scale sodium-ion batteries (SIBs) require high-performance, cost-effective cathode materials.
• Prussian blue analogs (PBAs) show promise for SIB cathodes but face challenges in achieving high capacity and long lifespan simultaneously.

Purpose of the Study:

• To develop low-cost ternary PBAs with improved capacity, cycling stability, and temperature adaptability for SIBs.
• To investigate the structural and electrochemical properties of novel PBA materials through structural regulation.

Main Methods:

• Synthesis of a series of low-cost ternary Prussian blue analogs (PBAs).
• Electrochemical characterization, including specific capacity and cycling performance testing.
• In situ techniques and density functional theory (DFT) calculations for in-depth analysis.
• Evaluation of temperature stability across a wide range (-20 to 55 °C).

Main Results:

• CuHCF-3 demonstrated a specific capacity of 132.4 mAh g^-1 with 73.3% retention over 1000 cycles.
• A reversible three-phase transition (monoclinic ↔ cubic ↔ tetragonal) was observed in CuHCF-3, driven by synergistic Mn-Cu interactions.
• Excellent temperature stability and 73.54% capacity retention over 850 cycles in 18650-type cells were achieved.

Conclusions:

• Synergistic Mn-Cu interactions in CuHCF-3 enhance conductivity, operating voltage, and mitigate volume changes, leading to superior performance.
• The developed ternary PBAs offer a promising pathway for durable, high-capacity electrode materials for SIB energy storage.
• This research provides valuable insights for designing advanced electrode materials for grid-scale energy storage applications.