SnO2 anode surface passivation by atomic layer deposited HfO2 improves Li-ion battery performance

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium ion batteries are crucial for energy storage.
• Tin dioxide (SnO2) anodes offer high theoretical capacity but suffer from poor cycling stability.
• Surface passivation is a key strategy to improve anode performance.

Purpose of the Study:

• To investigate the impact of nanoscale hafnium dioxide (HfO2) surface passivation on SnO2-based anodes for lithium ion batteries.
• To understand the mechanism by which HfO2 coatings enhance battery performance.

Main Methods:

• Atomic Layer Deposition (ALD) was used to create HfO2 surface passivation layers on SnO2-based anodes.
• Electrochemical performance was evaluated through capacity measurements at a specific current density over 100 cycles.
• Material analysis was conducted to characterize the HfO2 layers and their interaction with the SnO2 anodes.

Main Results:

• HfO2-coated SnO2 anodes demonstrated significantly improved battery capacity (853 mAhg(-1)) compared to uncoated anodes (548 mAhg(-1)) after 100 cycles at 150 mAg(-1).
• The HfO2 layers were found to be amorphous, conformably coating the SnO2 anodes.
• HfO2 protected the anodes from electrolyte reactions and buffered volume changes during cycling.
• A chemical interaction between HfO2 and SnO2 was observed, contributing to increased capacity despite HfO2's electrochemical inactivity.

Conclusions:

• Nanoscale HfO2 surface passivation via ALD is an effective strategy to enhance the performance of SnO2-based anodes in lithium ion batteries.
• The amorphous nature of the HfO2 layer is crucial, allowing sufficient lithium-ion diffusion for efficient electrochemical processes.
• HfO2 coatings improve capacity retention and battery longevity by preventing side reactions and accommodating volume expansion.