Stress-Dispersed Nanoconstruction of CoMoP Anode: Improved Na-Storage Stability and Reversibility

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Metal phosphide anodes suffer from poor reversibility and volume expansion, leading to low initial Coulombic efficiency (ICE) and capacity degradation in sodium-ion batteries.
• Existing materials struggle with structural instability during electrochemical cycling.

Purpose of the Study:

• To fabricate a novel three-dimensional ordered porous (3DOP) bimetallic phosphide (CoMoP) anode material.
• To address the poor reversibility and volume variation issues in metal phosphide anodes for sodium-ion batteries.

Main Methods:

• Fabrication of 3DOP CoMoP nanoconstruction.
• In situ and ex situ characterizations.
• Electrochemical measurements including galvanostatic cycling and rate capability tests.

Main Results:

• 3DOP CoMoP demonstrated a reduced Gibbs free energy change for the redox reaction and improved conductivity compared to CoP and MoP.
• The 3DOP architecture effectively dispersed stress and reduced strain, enhancing structural stability.
• Achieved a high ICE of 58% at 0.1 A g⁻¹, enhanced reaction dynamics, and excellent cycling stability with 0.04% capacity decay per cycle at 1 A g⁻¹ after 1000 cycles.

Conclusions:

• The developed 3DOP CoMoP material offers a promising solution for reversible sodium storage.
• This work provides a new strategy to overcome the challenges of redox chemistry reversibility and volume expansion in secondary batteries.