Ubiquitous in consumer electronics and emergent in transportation and stationary applications, lithium-ion batteries (LIB) are the state-of-the-art energy storage technology due to their energy density, roundtrip efficiency, and cycle life.^1,2 While the past decade has seen a steady decline in battery price and concomitant increase in energy density due to a combination of materials development, manufacturing advances, and market scale,^3,4 current LIBs are still unable to meet the often incongruous power and energy requirements of newer applications (e.g., fast charging of energy-dense batteries).^5,6 In addition, these more extreme operating environments challenge battery longevity and safety, necessitating responsive balance-of-plant systems which include thermal management systems that control cell temperatures using heat transfer media. At elevated temperatures, accelerated solid-electrolyte interphase growth and component decomposition may lead to capacity/power fade,^7,8 and, in the worst cases, thermal runaway and hazardous releases. Within the battery cell, temperature gradients lead to non-uniform electrode reaction distribution, and subsequently reduced cell performance and cycle life.⁸ Thus, typical LIB operating temperature ranges are constrained between 20 ℃ and 40 ℃, with minimal temperature differences across the cell. Most current thermal management systems rely on heat exchange through the surface or tab of the cell with a cooling media (air, liquid, phase-change materials, etc.).^9,10 While generally sufficient under many of today’s applications (low C-rates), this approach can be challenged by newer applications, such as those that require high power input/output (EV fast charging, electric aviation), or need large battery formats (stationary storage systems).

In this presentation, we will describe a novel concept of thermal management through forced convection of the electrolyte through the porous electrodes and separator. By leveraging battery simulation and dimensional analysis, we demonstrate that: (1) electrolyte convection provides efficient heat removal capability by carrying the generated heat out of the cell through the flowing medium; (2) the elimination of electrolyte concentration gradient by flow, and the resulting smaller ohmic resistance, concentration and activation overpotentials, help prevent cell temperature rise through reduced heat generation rate. Compared to current thermal management systems, this approach offers several important potential advantages, including (1) reduced internal temperature gradient, (2) rapid response time to temperature regulation, (3) simplifications to manufacturing, and ultimately, and (4) reduced system costs and improved battery safety.

References:

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