Long-Cycle-Life Sodium-Ion Battery Fabrication via a Unique Chemical Bonding Interface Mechanism

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Titanates are promising anode materials for sodium-ion batteries (SIBs).
• Key challenges include limited temperature suitability and cycle life.
• Practical application of titanates is hindered by these fundamental issues.

Purpose of the Study:

• To develop a novel hollow sodium titanate microsphere (H-NTO) with an improved interface for SIBs.
• To enhance the cycle life and low-temperature performance of titanate anodes.
• To investigate the interfacial chemistry critical for stable SIB operation.

Main Methods:

• Synthesis of hollow Na2Ti3O7 microspheres (H-NTO) with a chemically bonded NTO/C(N) interface.
• Theoretical calculations to understand interface stabilization.
• Electrochemical testing in conventional ester electrolytes at varying temperatures.

Main Results:

• The NTO/C(N) interface stabilizes the crystal structure of H-NTO.
• The H-NTO anode achieved 80,000 cycles with negligible capacity loss in ester electrolyte.
• Stable cycling for 200 days at -40°C was observed without capacity degradation.
• A stable solid electrolyte interphase (SEI) was formed due to electrolyte/electrode interface adaptability.

Conclusions:

• The NTO/C(N) interface and adaptable electrolyte/electrode interface are crucial for excellent cycling stability.
• Titanates can adapt to volume changes at low temperatures, especially in ether-based electrolytes.
• This work provides insights into long-cycle mechanisms for titanate anodes in SIBs.