Li-Ion Battery Module Elastic Plastic Film Compression
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Solution Overview
Problem
Existing methods for mechanically fixing and thermally contacting Li-ion cells, such as those used in thin pouch cells and prismatic metal case cells, face challenges in maintaining consistent pressure and thermal conductivity due to variations in cell thickness and surface unevenness over the battery's lifespan, as well as fluctuations in the production process.
Innovation Solution
A method utilizing an elastically plastic film, which can yield plastically to compensate for cell thickness changes and provide consistent pressure, combined with excellent thermal conductivity using expanded graphite for improved temperature control, ensuring even loading and thermal connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical compression is used for fixing and thermal contacting, then cells are mechanically fixed and thermally contacted, but pressure consistency deteriorates due to cell thickness variations and surface unevenness
Solution Approach 1:
The patent changes the physical state of the compression element from rigid to elastically plastic, allowing it to deform and adapt to varying cell dimensions. This parameter change enables the compression element to maintain consistent pressure despite manufacturing variations in cell thickness and surface flatness.
Solution Approach 2:
The patent employs a composite structure combining rigid housing components with an elastically plastic compression element. This composite approach integrates the structural support function of rigid materials with the adaptive pressure distribution function of elastically plastic materials, resolving the contradiction between mechanical fixation reliability and pressure consistency.
2Strength
If rigid compression elements are used, then structural support is provided, but adaptation to cell thickness variations is lost
Solution Approach 1:
The compression element's material parameter is changed from rigid to elastically plastic, enabling it to undergo permanent deformation that adapts to cell thickness variations while maintaining sufficient structural support capability.
Solution Approach 2:
The compression element transitions from a static rigid structure to a dynamic elastically plastic component that can deform and redistribute stress, providing both structural support and adaptability to dimensional variations.
3Temperature
If high compression force is applied, then thermal contact is improved, but cell stress increases affecting service life
Solution Approach 1:
The elastically plastic compression element changes from a high-stress rigid contact to a lower-stress adaptive contact that deforms to achieve thermal contact, reducing peak stresses on the cell while maintaining thermal coupling.
Solution Approach 2:
The elastically plastic material acts as a cushioning element that absorbs and distributes compression forces before they reach the cell, preventing stress concentration and protecting the cell from excessive stress while maintaining thermal contact.
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 approach maintains consistent pressure and thermal performance across the battery's lifespan, accommodating thickness variations and surface irregularities, while allowing for robust and cost-effective manufacturing processes.
Implementation Method 1
an elastically plastic film, which can yield plastically to compensate for cell thickness changes
Implementation Method 2
The breathing of the cell, the swelling and shrinking of the cell thickness when charging and discharging the cell, is compensated for by the elastic component
Implementation Method 3
the expanded graphite has excellent thermal conductivity and thus has a positive effect on the temperature control of the cell
Data Source
Figure 1a~2
Figure 3
AI summary
The invention creates a method for producing Li-ion battery modules (B), which comprises the following steps: placement of an elastic plastic device (F; F'; E) between at least two cells (Z) of a battery module (B); displacement-controlled compression of the at least two cells (Z) of the battery module (B) and of the elastic plastic device (F; F'; E) arranged between the at least two cells (Z). The invention also creates a corresponding Li-ion battery module (B).