Secondary Battery Cell Case Bottom Geometry for Double-Seam Cooling
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Solution Overview
Problem
The cooling efficiency of secondary battery cell cases is compromised by double seams projecting out from the container ends, which hinder effective contact with cooling devices or thermal pads, especially in battery modules with multiple cells, leading to reduced cooling performance.
Innovation Solution
The cell case design features a can bottom with a convex structure, where a specific area of the bottom is positioned relative to the double seam to enhance contact with cooling surfaces, with area ratios S1 and S2 of 50% or more, and a sheet thickness of 0.20 mm or less, allowing improved thermal conductivity and structural strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double seam structure is used to join the can bottom to the can body, then the hermeticity and sealing performance are improved, but the cooling efficiency deteriorates due to the projecting double seam hindering contact with cooling devices
Solution Approach 1:
A thermal pad is introduced as an intermediary component between the battery cell and the cooling device. The thermal pad compensates for the irregular surface created by the double seam, ensuring continuous thermal contact while maintaining the hermetic sealing provided by the double seam structure.
Solution Approach 2:
The thickness and thermal conductivity parameters of the thermal pad are optimized to compensate for the double seam projection height. By adjusting these parameters, the thermal contact is improved without compromising the sealing integrity of the double seam joint.
2Temperature
If the can bottom sheet thickness is reduced to improve cooling efficiency, then the thermal conductivity is improved, but the structural strength deteriorates
Solution Approach 1:
The can bottom is constructed using composite material structure with optimized thickness that balances thermal conductivity and structural strength. The double seam reinforcement compensates for the reduced material thickness, maintaining strength while improving heat dissipation.
Solution Approach 2:
The thermal pad acts as a mediator that compensates for the reduced can bottom thickness. It provides the necessary thermal contact and distributes heat effectively, allowing the use of thinner can bottom material without compromising either strength or cooling efficiency.
3Strength
If a three-piece can structure is used to increase structural strength, then the can body strength is improved, but the device complexity increases compared to two-piece can structures
Solution Approach 1:
The can structure is segmented into three pieces (can body, can bottom, and can lid) to concentrate strength at the critical joint areas where double seams are formed. This segmentation allows for optimized reinforcement at connection points without unnecessarily complicating the entire structure.
Solution Approach 2:
The thermal pad serves as an intermediary that simplifies the thermal management interface despite the three-piece structure. It provides a uniform thermal contact surface that masks the complexity of the multi-piece construction from the cooling system perspective.
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 design enhances cooling efficiency by ensuring effective contact between the cell case and cooling devices or thermal pads, while also increasing the structural strength of the cell case compared to traditional two-piece can structures, thereby improving overall thermal management and performance.
Implementation Method 1
a sheet thickness of 0.20 mm or less, allowing improved thermal conductivity
Data Source
AI summary
A cell case of a secondary battery having a rectangular tube-shaped can body, a can bottom double seamed to a bottom end of the can body, and a can lid double seamed to a top end of the can body, in which cell case of a secondary battery, an area ratio S1 of part of the can bottom, including a portion 1 between a plane vertical to the can body a distance of 0.5 mm above a bottom end of a double seam of the can body and the can bottom and a plane vertical to the can body a distance of 1.0 mm below the bottom end of the double seam, with respect to a cross-sectional area of the can body at the bottom end of the double seam is 50% or more, and a battery module having a plurality of such cell cases are provided.