CuSe₂ Nanocubes Enabling Efficient Sodium Storage.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) are a promising alternative to lithium-ion batteries (LIBs).
• Copper selenides are potential anode materials for SIBs, offering high theoretical capacity and conductivity.
• Challenges for copper selenides in SIBs include poor rate performance and capacity fading.

Purpose of the Study:

• To synthesize single-crystalline CuSe2 nanocubes (CuSe2 NCs) for SIB anodes.
• To evaluate the electrochemical performance of CuSe2 NCs in SIBs.
• To investigate the mechanism behind the enhanced electrochemical performance.

Main Methods:

• Solvothermal synthesis of single-crystalline CuSe2 NCs.
• Electrochemical testing of CuSe2 NCs as SIB anodes.
• Ex situ X-ray diffraction (XRD) analysis.
• Density functional theory (DFT) calculations.

Main Results:

• CuSe2 NCs exhibited nearly 100% initial Coulombic efficiency.
• Outstanding long cycle life was achieved: 380 mA h g⁻¹ after 1700 cycles at 10 A g⁻¹.
• Unprecedented rate performance of 344 mA h g⁻¹ at 50 A g⁻¹ was demonstrated.
• XRD revealed crystalline transformations during cycling.
• DFT suggested fast ion diffusion kinetics contributes to performance.

Conclusions:

• Single-crystalline CuSe2 NCs are highly effective anode materials for SIBs.
• The synthesized material overcomes the limitations of poor rate performance and capacity fading.
• The study provides a theoretical basis for the practical application of copper selenides in SIBs.