Zigzag-Folded Separator Electrode Stack for Thin Li-Ion Cells
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Solution Overview
Problem
The challenge is to enhance the energy density of lithium secondary batteries while maintaining product quality and preventing short circuits, particularly as the thickness of batteries is reduced and the dimensions of components need to be precisely adjusted.
Innovation Solution
An electrode assembly with a zigzag-folded separator is used, where anode and cathode plates are alternately stacked between folded portions of the separator, and the separator is wound around the outer edge of the stack, with an anode plate at the top and bottom, and fixed to the side surface to prevent protrusion and ensure alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of secondary batteries is reduced to increase energy density, then volumetric energy density is improved, but the risk of short circuit between electrodes increases and product quality control becomes more difficult
Solution Approach 1:
The separator is folded in a zigzag shape (M-folding) along the width direction, transforming the flat 2D separator into a 3D structure with alternating upward and downward folds. This dimensional transformation allows the separator to extend vertically between electrodes while maintaining horizontal spacing, effectively preventing short circuits in the reduced-thickness battery configuration
Solution Approach 2:
The separator is divided into multiple folded sections creating alternating upward and downward portions. Each fold segment acts as an independent barrier between anode and cathode plates, with folded portions providing additional separation at critical interfaces. This segmentation ensures that even if one section fails, other segments maintain electrical isolation
2Manufacturing precision
If the dimensions and spacings of individual components are adjusted to maintain product quality, then alignment precision is improved, but the device complexity increases
Solution Approach 1:
The folded separator performs multiple functions simultaneously: it provides electrical insulation between electrodes, maintains precise spacing through its geometric structure, prevents electrode deformation, and guides component alignment during assembly. The alternating upward and downward folds create self-aligning features that simplify manufacturing while ensuring consistent positioning
Solution Approach 2:
The zigzag folding pattern introduces controlled curvature and three-dimensional geometry to the separator structure. The alternating peaks and valleys of the folds create natural spacing zones that accommodate electrode plates of varying dimensions, providing tolerance for manufacturing variations while maintaining precise alignment
Data Source
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AI summary
An electrode assembly for secondary battery according to an Example of the present application may comprise a plurality of anode plates; a plurality of cathode plates; and a separator disposed between the plurality of cathode plates and the plurality of anode plates, wherein the separator may be folded in a zigzag shape, and the plurality of anode plates and the plurality of cathode plates may be alternately stacked in a section between folded portions of the separator to form a stack, and an anode plate may be disposed on an uppermost portion and a lowermost portion of the stack.