Dual-Structural-Unit-Designed Bismuth Titanium Oxides: -70 to 80°C Ultra-Wide Temperature Adaptability and...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries are cost-effective for large-scale energy storage but require high-performance anode materials.
• Bismuth (Bi)-based anodes offer high theoretical capacity but suffer from poor cycle life, rate capability, and operating temperature range.

Purpose of the Study:

• To develop an innovative Bi-based anode material for sodium-ion batteries.
• To improve cycle life, rate capability, and operating temperature range of Bi-based anodes.

Main Methods:

• Integration of bismuth (Bi) as the sodium storage unit with a robust Ti-O framework.
• Systematic investigation of different compounds, synthesis, and modification methods.
• Optimization of crystal structure, size, morphology, and conductivity of the anode material.

Main Results:

• The optimal Bi₄Ti₃O_12-x anode demonstrated a reversible capacity of 330 mAh g^-1 at 0.5 C.
• Exceptional performance was observed at high rates (132 mAh g^-1 at 150 C) and ultra-wide temperatures (-70°C to 80°C).
• High capacity retention (97% at 25°C, 61% at -40°C) over 24,000 cycles was achieved, with 151 mAh g^-1 at -55°C.

Conclusions:

• The proposed design of alloy materials within a stable host framework is a promising strategy for practical sodium-ion battery electrodes.
• This approach effectively addresses limitations in low-temperature and fast-charging performance for energy storage applications.