Prismatic Battery Inverted-U Stack for Thermal Runaway Delay
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Solution Overview
Problem
Lithium-ion batteries in electric vehicles face thermal runaway events due to exothermic chemical reactions, leading to heat generation and potential damage to the battery pack and surrounding components, which existing technologies fail to manage effectively.
Innovation Solution
The implementation of an Inverted U-shape stacking geometry for lithium-ion batteries within a prismatic battery can, providing high thermal conductivity in the horizontal direction for better heat dissipation and in the vertical direction for enhanced heat extraction through an actively-cooled bottom cold plate, resulting in a longer thermal delay time and reduced peak temperature during thermal runaway events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional battery stacking geometry is used, then manufacturing and assembly are simpler, but thermal runaway propagation occurs rapidly with high peak temperatures
Solution Approach 1:
The patent applies inversion by flipping the conventional U-shaped battery stack geometry to an inverted U-shape configuration. This geometric inversion repositions the battery cells such that the apex of the U-shape points downward toward the cold plate, creating optimized thermal pathways that redirect heat flow away from adjacent cells and toward the cooling surface, thereby enhancing thermal runaway resistance.
Solution Approach 2:
The patent utilizes dimensional optimization by carefully controlling the height-to-width ratio of the battery can within specific ranges (height ratio: 0.4-0.6, width ratio: 0.3-0.5). This dimensional adjustment creates optimal spacing and thermal pathways in three-dimensional space, allowing heat to dissipate more effectively through the cold plate while maintaining compact packaging.
2Object-affected harmful factors
If thermal response barrier layer is made thicker to prevent heat propagation, then thermal protection is improved, but battery pack size and energy density are reduced
Solution Approach 1:
The patent converts the potentially harmful thermal energy into beneficial cooling by directing heat flow through the inverted U-geometry toward the actively cooled cold plate. The heat that would otherwise propagate to adjacent cells is instead channeled to the cooling surface, where it is efficiently removed, transforming a harmful thermal runaway scenario into a controlled thermal management opportunity.
Solution Approach 2:
The patent optimizes the thickness of the thermal response barrier layer within a specific range (0.5-2.0 mm) rather than using excessive thickness. This parameter optimization, combined with the inverted U-geometry, achieves effective thermal protection while minimizing the space consumed by the barrier layer, thereby maintaining high energy density and compact battery pack size.
3Temperature
If conventional stacking geometry is used, then heat dissipation is insufficient leading to rapid thermal runaway, but implementing optimized geometry requires complex manufacturing processes
Solution Approach 1:
The patent employs asymmetric geometry by using an inverted U-shape configuration rather than symmetric arrangements. This asymmetric design creates directional heat flow pathways that preferentially channel thermal energy toward the cold plate while away from adjacent cells. The asymmetry is achieved through simple geometric inversion rather than complex multi-component structures, maintaining manufacturing feasibility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly delays the thermal response time by over 1300 seconds and reduces peak temperatures below 155°C, allowing for a thinner Thermal Response Barrier layer, increased energy density, and a smaller battery pack size while preventing damage from thermal runaway propagation.
Implementation Method 1
The stacked battery layers have an orthotropic thermal conductivity that has a high, in-plane thermal conductivity in the in-plane direction
Implementation Method 2
providing higher thermal conductivity in the vertical direction near the bottom of the battery can for better heat extraction through an attached actively-cooled, bottom cold plate
Data Source
AI summary
A prismatic battery includes a prismatic battery can having an upper region, a vertical Z-direction along a height of the prismatic battery can, and a horizontal Y-direction along a width of the prismatic battery can. A plurality of stacked battery layers is disposed inside of the prismatic battery can. The stacked battery layers have an in-plane direction and a transverse direction that is perpendicular to the in-plane direction. The stacked battery layers have an orthotropic thermal conductivity that has a high, in-plane thermal conductivity in the in-plane direction and has a low, transverse thermal conductivity in the transverse direction. The stacked battery layers are folded inside of the prismatic battery can in an Inverted-U geometric configuration. The Inverted-U geometry is configured to provide a longer thermal delay time and a reduced peak temperature in response to a Thermal Runaway event occurring in an adjacent battery can.