Biphasic MoO₂/Mo₂C-Passivated Graphite Anodes for Fast-Charging Lithium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Fast charging of lithium-ion batteries degrades performance, especially with thick electrodes.
• This decay stems from kinetic limitations at the graphite anode interface, leading to lithium plating.

Purpose of the Study:

• To engineer a novel biphasic passivation layer for graphite anodes.
• To enhance fast-charging capabilities and long-term cycle durability of lithium-ion batteries.

Main Methods:

• Developed an ultrathin MoO2/Mo2C biphasic layer using a polyelectrolyte-assisted adsorption approach.
• Characterized the layer's properties, including ionic conductivity, surface diffusion, and electrical conductivity.
• Tested the performance of the modified graphite anode under fast-charging conditions.

Main Results:

• The MoO2 outer layer stabilized the solid electrolyte interphase (SEI), suppressing excessive formation and promoting a robust, ionically conductive SEI.
• The Mo2C inner layer facilitated fast lithium-ion intercalation with low adsorption energy and high electrical conductivity.
• The modified anode achieved 80% state of charge in 7.4 minutes and retained 78.3% capacity after 600 fast-charge cycles at 3.2 mAh cm-2.

Conclusions:

• The MoO2/Mo2C biphasic layer effectively addresses interfacial kinetic limitations in graphite anodes.
• This surface engineering approach significantly advances fast-charging performance and cycle durability for high-performance lithium-ion batteries.