A Rhombic 2D Conjugated Metal-Organic Framework as Cathode for High-Performance Sodium-Ion Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• 2D conjugated metal-organic frameworks (2D c-MOFs) are promising for energy storage but face challenges like low capacity and poor cycling life.
• Existing 2D c-MOFs often suffer from underutilization of active sites, limiting their practical application.

Purpose of the Study:

• To develop a novel 2D c-MOF cathode material for sodium-ion batteries (SIBs) with improved electrochemical performance.
• To investigate the effect of linker design (narrow energy gap) and topology (rhombus) on battery performance.

Main Methods:

• Synthesis and characterization of Cu-TBA, a 2D c-MOF with a rhombus topology and large conjugation units.
• Electrochemical testing of Cu-TBA as a cathode material in SIBs, including capacity, rate capability, and cycling stability measurements.
• Comparison with a hexagonal counterpart (Cu-HHTP) to highlight performance differences.

Main Results:

• Cu-TBA exhibits a high specific surface area (613 m² g⁻¹) and a metallic band structure.
• Cu-TBA demonstrates superior reversible capacity (153.6 mAh g⁻¹ at 50 mA g⁻¹) compared to hexagonal analogs.
• Exceptional cyclability was observed, with minimal capacity decay after 3000 cycles at 1 A g⁻¹.

Conclusions:

• Narrowing the energy gap of organic linkers in 2D c-MOFs is an effective strategy to enhance electrochemical performance for SIBs.
• The rhombus topology and large conjugation units of Cu-TBA contribute to its outstanding performance as a cathode material.
• This work expands the potential applications of 2D c-MOFs in advanced energy storage systems.