Wound Electrode Assembly With Variable Cutouts to Prevent Cracking
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Solution Overview
Problem
The expansion and contraction of the negative electrode non-coated portion at the outermost periphery of the electrode assembly in secondary batteries cause cracking due to volume changes during charging and discharging.
Innovation Solution
The electrode assembly incorporates a variable unit with non-straight cutout portions and variable portions on the outermost peripheral negative electrode non-coated portion to accommodate volume changes, featuring a non-straight shape that extends obliquely to compensate for expansion and includes fixed portions to prevent cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of slits are formed in the current collector to increase electrode flexibility, then flexibility is improved, but the structural strength of the current collector deteriorates
Solution Approach 1:
The current collector uses a composite structure combining aluminum foil with an aluminum alloy mesh layer. The aluminum alloy mesh provides structural strength while the slits in the aluminum foil layer provide flexibility. This composite approach allows both flexibility and strength to coexist without compromising either property.
Solution Approach 2:
The current collector is segmented into multiple functional layers: an aluminum foil layer with slits for flexibility, and an aluminum alloy mesh layer for structural support. This segmentation allows each layer to perform its specific function optimally while contributing to the overall performance of the current collector.
2Quantity of substance
If the electrode structure is made complex to improve battery capacity, then battery capacity is improved, but the manufacturing complexity increases
Solution Approach 1:
The electrode is segmented into a集流体 layer and an active material layer, with the current collector further divided into functional sub-layers. This segmentation allows for optimized performance in each layer while maintaining clear manufacturing boundaries and processes.
Solution Approach 2:
The electrode uses composite materials including aluminum foil, aluminum alloy mesh, and active materials. This composite approach enables high battery capacity through optimized material properties while keeping the overall structure relatively simple and manufacturable.
3Weight of moving object
If the current collector is made thinner to reduce battery weight, then battery weight is reduced, but the mechanical strength deteriorates
Solution Approach 1:
The current collector employs a composite structure where thin aluminum foil provides low weight, while the integrated aluminum alloy mesh layer provides the necessary mechanical strength. This allows the current collector to be lightweight yet structurally sound.
Solution Approach 2:
The current collector is segmented into weight-optimized thin aluminum foil and strength-providing aluminum alloy mesh components. This segmentation enables the thin foil to minimize weight while the mesh structure maintains mechanical integrity.
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 effectively prevents cracking of the electrode non-coated portion by allowing the assembly to expand and contract without increasing resistance, ensuring stability and safety.
Implementation Method 1
the aluminum alloy mesh layer has a mesh structure and provides support to the current collector
Data Source
Figure 1
Figure 2(a)~2(b)
Figure 3(a)~3(b)
AI summary
The present invention relates to an electrode assembly, which is made by winding a positive electrode, a separator, and a negative electrode, in which the negative electrode includes a negative electrode active material portion made by applying a negative electrode active material onto a negative electrode current collector, a central negative electrode non-coated portion positioned at a winding center portion and having no negative electrode active material, and a negative electrode non-coated portion including an outermost peripheral negative electrode non-coated portion positioned at an outermost winding periphery, in which a variable unit is provided on the outermost peripheral negative electrode non-coated portion and configured to adjust a length or width thereof, and in which the variable unit includes one or more cutout portions having a non-straight shape, and a variable portion configured to adjust a length or width thereof.