Pressure-Activated Binding Material for Battery Cell Fixing
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Solution Overview
Problem
Lithium-ion secondary batteries face issues during drop tests, such as top sealing bursts, electrolyte leakage, separator wrinkling, and internal short circuits, which conventional adhesive tapes fail to address effectively without compromising energy density.
Innovation Solution
An electrochemical energy storage device with a binding material comprising a first adhesive layer on the cell and a second functional layer that adheres to the package only under pressure, allowing for secure connection without initial adhesive interference, thus preventing separator wrinkling and internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional double-sided adhesive paper is used to fix the cell to the package, then the cell is securely fixed and drop test problems are resolved, but the cell becomes difficult to insert into the package due to both surfaces being adhesive
Solution Approach 1:
The binding material is segmented into two distinct functional layers: a first adhesive layer for bonding to the cell and a second functional layer for bonding to the package. This segmentation allows each layer to perform its specific function independently, enabling easy insertion while ensuring reliable fixation.
Solution Approach 2:
Different layers of the binding material have different local qualities - the first adhesive layer has adhesive properties for cell attachment, while the second functional layer has non-adhesive properties during insertion that become adhesive under pressure for package attachment. This local quality differentiation resolves the contradiction between ease of insertion and fixing reliability.
2Reliability
If adhesive tape is used to tie the cell or enlarge the top sealing region, then top sealing burst and electrolyte leakage are prevented, but energy density decreases
Solution Approach 1:
The invention extracts the sealing and fixation function from the top sealing region and electrode structure, relocating it to the binding material positioned between the cell and package. This allows the top sealing region to be minimized for high energy density while the binding material provides the necessary sealing and fixation functions.
Solution Approach 2:
The binding material acts as an intermediary element between the cell and package, providing sealing and fixation functions without requiring enlargement of the top sealing region or modification of the electrode structure. This intermediary approach maintains high energy density while ensuring sealing reliability.
3Reliability
If the second functional layer is made adhesive from the beginning, then the cell is firmly fixed to the package, but the cell cannot be easily inserted into the package
Solution Approach 1:
The second functional layer transitions from a non-adhesive state during assembly to an adhesive state under pressure during fixation. This dynamic property change allows easy insertion during assembly while ensuring strong fixation when pressure is applied, resolving the contradiction between ease of assembly and fixing strength.
Solution Approach 2:
The cell is inserted into the package first when the second functional layer is non-adhesive, and then pressure is applied to activate the adhesive property of the second functional layer for firm fixation. This preliminary action sequence resolves the contradiction by separating the insertion and fixation steps.
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 ensures the lithium-ion secondary battery can be easily inserted into the package and withstands drop tests without top sealing bursts or internal short circuits, maintaining energy density and cycle life performance.
Implementation Method 1
The first adhesive layer is directly adhered and positioned on an outer surface of the cell
Implementation Method 2
the second functional layer is not adhered to the package before a pressure is applied on the electrochemical energy storage device, and the second functional layer is adhered to the package after the pressure is applied
Data Source
Figure 1~2
Figure 3~7
AI summary
An electrochemical energy storage device comprises a cell (1), an electrolyte and a package (2). The electrochemical energy storage device further comprises a binding material (3) positioned between the cell (1) and the package (2). The binding material (3) comprises a first adhesive layer (31) and a second functional layer (32). The first adhesive layer (31) is directly or indirectly adhered and positioned on an outer surface of the cell (1); the second functional layer (32) is positioned on a side of the first adhesive layer (31) opposite to a surface of the first adhesive layer (31) directly or indirectly adhered on the cell (1), the second functional layer (32) is not adhered to the package (2) before a pressure is applied, and the second functional layer (32) is adhered to the package (2) after the pressure is applied.