Good Solid-State Electrolytes Have Low, Glass-Like Thermal Conductivity.

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Physics

Background:

• Effective thermal management is vital for lithium-ion battery safety, reliability, and performance.
• Understanding the thermal conductivity of battery materials is key to controlling battery temperature and distribution.

Purpose of the Study:

• To systematically measure the thermal conductivity of three major classes of solid electrolytes (SEs).
• To investigate the temperature dependence of thermal conductivity in SEs within the range of 150 K to 350 K.

Main Methods:

• Quantitative measurements of thermal conductivity were performed on various oxide, sulfide, and halide solid electrolytes.
• The temperature dependence of thermal conductivity was analyzed across a range of 150 K to 350 K.

Main Results:

• Sulfide and halide SEs exhibited thermal conductivities between 0.45-0.70 W m⁻¹ K⁻¹.
• Oxide SEs, Li₆.₄La₃Zr₁.₄Ta₀.₆O₁₂ and Li₁.₅Al₀.₅Ge₁.₅(PO₄)₃, showed thermal conductivities of 1.4 W m⁻¹ K⁻¹ and 2.2 W m⁻¹ K⁻¹, respectively.
• Most SEs displayed a glass-like temperature dependence, with thermal conductivity increasing with temperature.

Conclusions:

• The low, glass-like thermal conductivity of SEs is linked to complex crystal structures and atomic-scale disorder.
• Measured thermal conductivities align with minimum thermal conductivity calculations, suggesting phonon mean-free-paths near atomic spacing.
• These findings are critical for designing advanced solid-state batteries with improved thermal management.