Planar Cell Tab Welding for Compact Battery Packs
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Solution Overview
Problem
Existing lithium battery pack assembly methods for vehicles are inefficient due to slow laser welding and costly, bulky designs, with excessive use of intermediate metal terminals and high maintenance requirements for ultrasonic devices.
Innovation Solution
A method for assembling planar cells in series using integrally made terminal tabs, which are directly welded together in an overlapping area, reducing the need for intermediate terminals and minimizing the distance between cells, thereby optimizing space and reducing the number of welds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If laser welding is used to connect terminal tabs, then welding strength is achieved, but production speed is slow and manufacturing cost increases
Solution Approach 1:
The patent merges multiple terminal tabs from different cells into a single common terminal structure. Instead of welding each tab separately to intermediate terminals, multiple tabs are directly connected to shared terminal pieces, reducing the total number of welding operations while maintaining connection strength
Solution Approach 2:
The patent extracts and eliminates the intermediate metal terminals from the assembly process. By directly connecting cell tabs to common terminal pieces, the complex multi-layer terminal structure is simplified, reducing both welding steps and structural complexity
2Reliability
If intermediate metal terminals are used to connect cells, then electrical connection is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes intermediate metal terminals from the cell assembly process. Cells are directly connected to common terminal pieces through their tabs, eliminating the need for separate intermediate terminal components and simplifying the overall structure
Solution Approach 2:
The common terminal pieces serve multiple functions: they act as both connection points for multiple cells and as the final terminal structure. This multi-functional design eliminates the need for separate intermediate terminals and simplifies the assembly process
3Productivity
If ultrasonic welding devices are used, then welding speed improves, but maintenance cost increases due to frequent sonotrode replacement
Solution Approach 1:
By merging multiple tabs into a single common terminal structure, the patent reduces the total number of welding operations required. This decreases both the initial production time and the cumulative wear on ultrasonic welding tools, reducing maintenance frequency
Solution Approach 2:
The patent adopts a design that tolerates the limited lifespan of ultrasonic sonotrodes. By minimizing the number of welds required and using simple tab-to-terminal connections, the system can operate effectively through multiple sonotrode replacement cycles, making the maintenance cost acceptable
4Quantity of substance
If planar pouch batteries with thin sides are used, then energy density is improved, but heat dissipation efficiency decreases
Solution Approach 1:
The patent arranges cells and terminals in a three-dimensional configuration where terminal pieces extend to provide heat dissipation surfaces. This adds thermal management capability in the vertical dimension while maintaining the thin-profile advantage of planar pouch batteries
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 results in a more compact, cost-effective battery pack with reduced production errors and maintenance costs, while simplifying the assembly process and enhancing the structural integrity of the battery pack.
Implementation Method 1
the tabs (6) having the same polarity of two adjacent cells (2), connected in series, are directly welded together
Data Source
Figure 1~2
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AI summary
A method for assembling cells installable in a vehicular battery pack (10); the method including the steps of stacking a plurality of electrodes (3, 4) in such a way that the tabs (6) of each electrode with the same polarity are aligned with each other; arranging a first planar cell (2) and a second planar cell (2) in such a way that the tabs (6) having the same polarity are at least partially facing and at least partially superimposed in correspondence with an overlapping area (7) of each tab (6), distal with respect to the main body (8); welding together, directly, at least one terminal tab (6) belonging to the first planar cell (2) and one terminal tab (6) belonging to the second planar cell (2) in correspondence with said overlapping area (7).