Boosting Sodium Storage in TiO₂ Nanotube Arrays through Surface Phosphorylation

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) are a scalable and low-cost energy storage solution.
• Anode materials for SIBs face challenges with low capacity and poor rate capability.

Purpose of the Study:

• To develop efficient anode materials for SIBs.
• To investigate surface phosphorylated TiO₂ nanotube arrays as potential SIB anodes.

Main Methods:

• Electrochemical anodization of Ti metal in NH₄F solution.
• Phosphorylation using sodium hypophosphite.
• Characterization using in situ X-ray diffraction and transmission electron microscopy.

Main Results:

• Phosphorylated TiO₂ nanotube arrays achieved a reversible capacity of 334 mA h g^-1 at 67 mA g^-1.
• Demonstrated superior rate capability with 147 mA h g^-1 at 3350 mA g^-1.
• Exhibited stable cycling performance over 1000 cycles with excellent structural stability.

Conclusions:

• Surface phosphorylated TiO₂ nanotube arrays are effective anode materials for SIBs.
• The materials display near-zero strain and robust mechanical behavior during sodiation/desodiation.
• This work presents a promising strategy for enhancing SIB anode performance.