3D Simulation Study on Thermal Behavior and Thermal Stress of Lithium‐Ion Battery

Abstract

Temperature and thermal stress are crucial factors affecting the working performance and thermal safety of lithium‐ion batteries (LIBs). During the discharge process of the battery, the temperature increases. The thermal expansion stress caused by the entropy heat and the ohmic heat can lead to the battery's lifetime reduction and even thermal safety issues. Herein, based on the coupled electrochemical model, the LIB's thermal behavior and thermal stress distribution at a 1C discharge rate are simulated and analyzed. The results show that the temperature distribution inside the battery is mainly affected by the heat exchange surface and the position of the tabs during the discharging process, in which the localized high‐temperature region occurs in the positive tab. The thermal stress inside the battery enhances rapidly at both the beginning and end of the discharging process while increasing slowly in the middle.

Controlled Synthesis of High-Aspect-Ratio Nitrogen-Doped Nanoporous Graphene Fibers for Stable Lithium–Sulfur Batteries

“…In light of the structure, these NGFs have several structure merits that make them promising in energy storage. (i) In the aspect of electron transport, such NGFs not only offer high conductivity based on sp 2 hybrid carbon atoms; their high aspect ratio also enables orientated long-range conductivity, which is key for high power performance. , (ii) In the aspect of ion transport, the porous structure of NGFs enables effective channels with shortened ion access and fast transport of electrolytes, along with the improved surface properties due to nitrogen doping. , (iii) In the aspect of electrode stability, such one-dimensional nanostructures are constructed from interconnected graphene layers. It could offer long-range structure stability due to the uniform structure and strong tolerance to stress changes during the charge/discharge processes.…”

Methods for Quantifying Expansion in Lithium-Ion Battery Cells Resulting from Cycling: A Review

“…The generated friction during electric flow is entirely transformed into heat. Therefore, the heat production due to Joules heat is completely irreversible and happens during both charging and discharging [56,57]. Differences in the Joule heat production and the thermal expansion due to the different thermal and electrical conductivity exists also in the external interface of the battery cell, the tabs [58].…”

“…Entropy occurs due to the entropy change during electrochemical reactions from Gibbs free energy conversion to electrical energy. Since lithium-ion batteries have high specific energies, the Gibbs energy is high as well [57,59]. Heat generation due to entropy changes occurs exothermically during discharge and endothermically during charge, also contributing to reversible expansion.…”

Methods for Quantifying Expansion in Lithium-Ion Battery Cells Resulting from Cycling: A Review

“…The generated friction during electric flow is entirely transformed into heat. Therefore, the heat production due to joule heat is completely irreversible and happens during both charging and discharging [67,68]. Differences in the joule heat production and the thermal expansion due to different thermal and electrical conductivity exists also in the external interface of the battery cell, which are the tabs [69].…”

“…Entropy occurs due to the entropy change during electrochemical reactions from Gibbs free energy conversion to electrical energy. Since lithium-ion batteries have high specific energies, the Gibbs energy is high as well [68,70]. Heat generation due to entropy changes occurs exothermically during discharge and endothermically during charge, thus also contributing to reversible expansion.…”