Highly Anisotropic Thermal Transport in LiCoO₂

Area of Science:

• Materials Science
• Solid-State Chemistry
• Battery Technology

Background:

• Lithium cobalt oxide (LiCoO2) is a key cathode material in lithium-ion batteries.
• Its layered crystal structure influences anisotropic ionic and electronic transport.
• Heat transport properties of LiCoO2 remain poorly understood.

Purpose of the Study:

• To investigate the anisotropic thermal conductivity of LiCoO2.
• To understand the role of phonon behavior in heat transport.
• To assess the implications for thermal management in lithium-ion batteries.

Main Methods:

• Analysis of phonon dispersion and lifetimes using anharmonic lattice dynamics.
• Calculation of quantum-chemical force constants.
• Modeling of thermal conductivity at room temperature (300 K).

Main Results:

• Thermal conductivity in the ab plane is approximately 6 times higher than along the c axis at room temperature.
• An upper limit for average thermal conductivity is 38.5 W m⁻¹ K⁻¹, limited by short phonon lifetimes.
• Observed conductivities below 10 W m⁻¹ K⁻¹ are attributed to scattering from grain boundaries in polycrystalline samples.

Conclusions:

• Anharmonic interactions within the CoO2 network significantly limit phonon lifetimes and thus thermal conductivity.
• The anisotropic heat transport must be considered for effective thermal management in LiCoO2-based batteries.
• Understanding these thermal properties is crucial for battery performance and safety.