Lithium-ion batteries (LIBs) are widely used for electrical energy storage. The kinetics of charge transport, intercalation, and chemical reactions [1,2] in LIBs are strongly dependent on temperature. These processes, in turn, control cell round-trip efficiency and cycle life. For example, side reactions that irreversibly consume Li ions, for example, electrolyte decomposition, are accelerated at high temperatures. Furthermore, exposure of a battery to elevated temperatures, while beneficial for fast charging, leads to significant safety risks due to the potential for electrolyte decomposition, oxygen release by cathode materials, and if heat cannot be removed at an appropriate rate, thermal runaway. Greater understanding of the thermal properties of battery materials will facilitate advances in the engineering design and thermal management of LIBs is needed to improve safety and performance.The thermal properties of materials used in liquid-electrolyte-based batteries were summarized by Kantharaj et al. at both the device and material levels. [2] An additional level of complexity is created by the fact that the thermal conductivity of cathodes and anodes are known to depend on the state of charge, for example, the thermal conductivities of LiCoO 2 and graphite depend on Li composition. [3] From the cell assembly perspective, interfaces play a significant role in heat transfer. [4] For example, Lubner et al. characterized thermal resistances in a pouch-cell and showed that the thermal resistance of the separator-electrode interfaces accounts for up to 65% of the total thermal resistance within the cell. [4] Solid-state batteries (SSBs) are under intense investigation as safer, more robust, and higher energy-density alternatives to liquid-electrolyte-based LIBs. Similar to their liquidelectrolyte-based counterparts, SSBs also require thermal management strategies for dissipation of heat, especially in large, high-energy cell stacks. [2,5,6] If lithium metal is used as the SSB anode, which is highly attractive due to lithium's low reduction potential (−3.04 V vs standard-hydrogen-electrode) and high specific capacity (3860 mAh g −1 ), [7] temperature control becomes particularly important, as control of internal temperature distributions enhances the homogeneity of Li deposition and suppresses the formation of dendrites. [6] In Thermal management in Li-ion batteries is critical for their safety, reliability, and performance. Understanding the thermal conductivity of the battery materials is crucial for controlling the temperature and temperature distribution in batteries. This work provides systemic quantitative measurements of the thermal conductivity of three important classes of solid electrolytes (SEs) over the temperature range 150 < T < 350 K. Studies include the oxides

No abstract

Thermal resistances from interfaces impede heat dissipation in micro/nanoscale electronics, especially for high-power electronics. Despite the growing importance of understanding interfacial thermal transport, advanced thermal characterization techniques which can visualize thermal conductance across buried interfaces, especially for nonmetal-nonmetal interfaces, are still under development. This work reports a dual-modulation-frequency TDTR mapping technique to visualize the thermal conduction across buried semiconductor interfaces for β-Ga2O3-SiC samples.Both the β-Ga2O3 thermal conductivity and the buried β-Ga2O3-SiC thermal boundary conductance (TBC) are visualized for an area of 200 μm x 200 μm. Areas with low TBC values (≤20 MW/m 2 -K) are successfully identified on the TBC map, which correspond to weakly bonded interfaces caused by high-temperature annealing. The steady-state temperature rise (detector voltage), usually ignored in TDTR measurements, is found to be able to probe TBC variations of the buried interfaces without the limit of thermal penetration depth. This technique can be applied to detect defects/voids in deeply buried heterogeneous interfaces non-destructively, and also opens a door for the visualization of thermal conductance in nanoscale nonhomogeneous structures.

No abstract