Battery Module Compression Pad Structure for Constant Cell Pressure
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Solution Overview
Problem
Secondary battery modules face challenges in maintaining optimal performance and lifespan due to inappropriate pressure application, which can lead to electrode cracking, delamination, capacity reduction, and increased contact resistance.
Innovation Solution
The secondary battery module incorporates a cell stack with unit cells, first and second compression pads made of elastic material, and end plates that are irreversibly deformed to maintain constant pressure and limit maximum deformation, ensuring appropriate pressure is applied and deformation is controlled.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If appropriate pressure is applied to secondary battery cells, then optimal performance and lifespan are achieved, but device complexity increases due to the need for compression pads and end plates
Solution Approach 1:
Compression pads are introduced as intermediary elements between the end plates and battery cells to transmit and distribute pressure uniformly. These pads act as mediators that convert the force from the end plates into appropriate contact pressure on the cells, ensuring optimal performance while protecting the cells from direct mechanical stress
Solution Approach 2:
The end plates are designed with irreversible deformation capability, allowing them to change their physical state from flexible to rigid. This parameter change enables the end plates to maintain constant pressure on the battery cells over time, compensating for cell expansion and contraction while maintaining appropriate pressure levels
2Reliability
If pressure higher than appropriate is applied to secondary battery cells, then contact between electrode plates is improved, but electrode cracking and delamination occur
Solution Approach 1:
Compression pads made of elastic or compliant materials are used to apply pressure to the battery cells. These flexible elements distribute the pressure uniformly across the cell surfaces, preventing localized stress concentrations that would cause electrode cracking or delamination while still ensuring adequate contact between electrode plates
Solution Approach 2:
The compression pads serve as cushioning elements that absorb and distribute mechanical stress before it reaches the battery cells. By placing these protective layers in advance, the system prevents harmful high-pressure spikes from directly impacting the electrode structure
3Object-affected harmful factors
If pressure lower than appropriate is applied to secondary battery cells, then electrode plate damage is prevented, but regions of negative electrodes remain uncharged and contact resistance increases
Solution Approach 1:
Compression pads act as intermediary elements that ensure sufficient pressure transmission to maintain good contact between electrode plates and with current collectors. This intermediary pressure ensures that all regions of the negative electrodes are properly charged while preventing excessive force that could damage the electrode structure
4Object-affected harmful factors
If maximum deformation of secondary battery modules is limited, then interference with pack cases is prevented, but the structure requires additional constraints
Solution Approach 1:
End plates are designed to undergo irreversible deformation, changing their physical state from flexible to rigid over time. This parameter change allows the end plates to maintain constant pressure on the battery cells while limiting the maximum deformation of the entire module, preventing interference with pack cases without requiring additional external constraints
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 effectively limits maximum deformation and maintains constant pressure on the unit cells, enhancing the performance and lifespan of the secondary battery module by preventing electrode damage and ensuring even pressure distribution.
Implementation Method 1
The first compression pad may be configured to be compressed by volume expansion due to a change in a state of charge (SOC) of the plurality of unit cells to prevent the pair of end plates from being deformed
Implementation Method 2
The first compression pad may be made of an elastic material and may be reversibly deformable
Implementation Method 3
The pair of end plates may be made of metal and are configured to be irreversibly deformed by volume expansion due to deterioration of the plurality of unit cells
Data Source
AI summary
A secondary battery module includes: a cell stack including a plurality of unit cells; a first compression pad arranged between adjacent ones of the unit cells; and a pair of end plates facing each other at outer sides of the cell stack.