Battery Module Cell Stack Structure for Stable Pressing Force
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Solution Overview
Problem
Existing battery modules face challenges in reliably applying a pressing force to plate-shaped cells due to the reduction in pressure from pressure-curable adhesives spreading during curing, leading to increased contact resistance and reduced cell performance.
Innovation Solution
A battery module design incorporating a frame-shaped protruding portion on each cell with a filler that fills the inner space, where the filler's volume exceeds the space volume, ensuring a consistent pressing force is applied by limiting the filler's spread and maintaining the adhesive effect even after curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pressure-curable adhesive is used to bond plate-shaped cells, then the cells are bonded together in the stacking direction, but the adhesive spreads during curing which reduces its thickness and the pressing force it can apply
Solution Approach 1:
The adhesive bonding system is segmented into two functional parts: a thin adhesive layer for bonding and a separate filler material for maintaining pressing force. The filler is placed in a frame-shaped protruding portion that is distinct from the adhesive application area, allowing each material to perform its optimized function without interfering with the other.
Solution Approach 2:
The filler material acts as an intermediary between the adhesive and the cell surfaces. It transmits and maintains the pressing force that the adhesive applies to the cells, compensating for the adhesive's inability to maintain high force after spreading during curing.
2Area of stationary object
If the adhesive layer thickness is reduced due to spreading, then the bonding area increases, but the pressing force applied to the cells decreases
Solution Approach 1:
The system separates the bonding function (performed by the thin adhesive layer with large area) from the force application function (performed by the filler material). This segmentation allows the adhesive to spread and increase bonding area without compromising the pressing force, as the filler independently maintains the required force.
Solution Approach 2:
The design changes the physical state and placement of the filler material to maintain constant pressing force. The filler is placed in a confined frame-shaped portion and has a larger volume under atmospheric pressure, ensuring it maintains sufficient pressure on the cells despite the adhesive's spreading.
3Reliability
If the cell stack is pressed from both sides, then contact resistance between electrode plates is reduced, but the adhesive may spread more during pressing
Solution Approach 1:
The filler material serves as an intermediary that maintains the pressing force during and after the pressing operation. While the cell stack is pressed to reduce contact resistance, the filler in the frame-shaped protruding portion ensures the adhesive force is maintained, preventing the adhesive from spreading excessively even under pressing conditions.
Data Source
AI summary
A battery module includes a cell stack in which a plurality of plate-shaped cells is stacked such that each main surface, which is a surface of each of the plate-shaped cells in a cell thickness direction, faces one another.