Kinetic Limitations in Single-Crystal High-Nickel Cathodes.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• High-nickel cathodes are crucial for high-capacity, cost-effective lithium-ion batteries.
• Single-crystal cathodes offer an alternative to polycrystals to mitigate intergranular cracking.
• Concerns exist regarding the ionic transport and kinetic properties of single-crystal cathodes.

Purpose of the Study:

• To quantitatively assess the redox reaction kinetics in single-crystal LiNi0.8Mn0.1Co0.1O2.
• To investigate the influence of the state of charge (SOC) on redox kinetics.
• To understand the factors limiting kinetics in single-crystal electrodes.

Main Methods:

• Operando hard X-ray microscopy and spectroscopy were employed to study redox reactions.
• Transport measurements were conducted to evaluate ionic conductivity.
• Finite-element simulations were used to model and corroborate experimental findings.

Main Results:

• Redox kinetics in single-crystal LiNi0.8Mn0.1Co0.1O2 exhibit a strong dependence on SOC.
• Kinetics are sluggish at low SOC but accelerate significantly as SOC increases.
• Sluggish kinetics at low SOC are primarily governed by ionic transport limitations.
• Synergistic integration with polycrystals can alleviate kinetic limitations in single-crystal electrodes.

Conclusions:

• Single-crystal cathodes demonstrate tunable redox kinetics influenced by SOC.
• Ionic transport is a key limiting factor for kinetics in single crystals at low SOC.
• Hybrid electrodes combining single-crystal and polycrystal materials show promise for enhanced battery performance.