Water-Mediated Surface Engineering Enhances High-Voltage Stability of Fast-Charge LiCoO₂ Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium cobalt oxide (LCO) suffers from surface degradation during rapid charging and high-voltage operation due to side reactions and cobalt dissolution.
• Existing surface modification methods often fall short in addressing these stability issues under demanding conditions.

Purpose of the Study:

• To develop a water-mediated surface modification strategy for LCO to enhance its stability and cycling performance.
• To investigate the mechanism of surface passivation and its impact on electrochemical properties.

Main Methods:

• A water-mediated etching and cation exchange process was employed to modify the LCO surface.
• The modified LCO was characterized for its structural and surface properties.
• Electrochemical performance was evaluated through cycling tests at high current densities and elevated temperatures in full-cell configurations.

Main Results:

• The water-mediated strategy created a passivating layer on LCO, enhancing surface hydrophobicity and structural stability.
• Modified LCO showed 2.5 times better capacity retention than pristine LCO after 100 cycles at 1000 mA g⁻¹ (∼6C) and 4.5 V.
• Impressive cycling stability was maintained even at 45 °C and 500 mA g⁻¹ (∼3C).

Conclusions:

• The water-mediated approach offers a simple yet effective method for stabilizing LCO cathode materials.
• This strategy demonstrates broad applicability for surface modification of cathode materials in high-energy-density lithium-ion batteries.
• The findings provide valuable insights for designing more stable and durable LIBs.