Rigid and Flexible Wedge Compensation for Prismatic Cell Swelling
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Solution Overview
Problem
The existing solutions for compensating the swelling of electrochemical cells in batteries, such as using deformable foams or metal springs, fail to provide sufficient rigidity and controlled compression, leading to potential deformation or short-circuits and thermal conductivity issues in prismatic lithium-ion batteries.
Innovation Solution
A battery design that incorporates a rigid wedge with a hardness of at least 90 Shore A and a flexible wedge with a hardness up to 60 Shore A, both being electrically insulating, to maintain constant distance between cells and absorb swelling, with the flexible wedge capable of exerting controlled pressure to prevent deformation and thermal isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a deformable foam or polyurethane piece is used between cells to compensate swelling, then the swelling compensation function is provided, but the assembly rigidity is insufficient and compression force is not controlled
Solution Approach 1:
The compensation device is divided into two distinct segments: a rigid wedge providing structural support and rigidity, and a flexible wedge providing swelling compensation. This segmentation allows each component to specialize in its function without compromising the other.
Solution Approach 2:
The invention changes the physical parameters of the compensation material by selecting specific hardness ranges (rigid wedge: 60-90 Shore A, flexible wedge: 30-60 Shore A) to achieve different functional characteristics. This parameter-based differentiation resolves the contradiction between rigidity and flexibility.
2Adaptability or versatility
If a metal spring is used between cells to compensate swelling, then the swelling compensation function is provided, but short-circuit risk increases and thermal conductivity problems occur
Solution Approach 1:
The invention introduces polymeric wedge materials as intermediary elements between adjacent electrochemical cells. These polymers serve as mediators that provide mechanical compensation while simultaneously ensuring electrical insulation, thus eliminating the short-circuit risk associated with metal springs.
Solution Approach 2:
The invention changes the material composition parameter from metallic to polymeric, which fundamentally alters both the electrical conductivity (to insulating) and thermal conductivity properties, resolving the reliability and thermal management issues.
3Volume of stationary object
If cells are tightly packed in a rigid grouping box to maintain compactness, then space utilization is improved, but swelling-induced pressure causes box deformation or damage
Solution Approach 1:
The invention implements beforehand cushioning by placing compliant polymeric wedges between cells during assembly. These wedges are pre-positioned to absorb and distribute swelling pressures, cushioning the rigid grouping box from deformation or damage before it occurs.
Solution Approach 2:
The invention changes the mechanical parameter of the interface between cells from rigid-to-rigid contact to rigid-to-compliant contact, allowing the compliant polymer to deform and absorb pressure while maintaining compact overall dimensions.
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
The solution effectively maintains the constant length of the battery, prevents deformation of the grouping box, and ensures thermal isolation between cells, while ensuring compression of electrodes to preserve the active material strength, thereby addressing the swelling issue and maintaining battery integrity.
Implementation Method 1
the increase in thickness of the cell being associated with a reduction in thickness of the flexible wedge
Implementation Method 2
separated by a rigid wedge having a hardness greater than or equal to 90 Shore A according to the standard ASTM D 2240
Implementation Method 3
the rigid wedge and the flexible wedge being electrically insulating
Implementation Method 4
the flexible wedge comprises a material whereof the thermal conductivity is less than or equal to 0.5 W/(m·K)
Data Source
AI summary
The invention resolves the problem of swelling of sealing electrochemical cells of prismatic format when they are assembled side by side in a grouping box by proposing a battery comprising at least two electrochemical cells (1a, 1b) of prismatic format, wherein the electrochemical cells are separated by a rigid wedge (2) having a hardness greater than or equal to 90 Shore A according to the standard ASTM D 2240 and by a flexible wedge (3) having a hardness of up to 60 Shore A according to the standard ASTM D 2240, the rigid wedge and the flexible wedge being electrically insulating.