Stack/Folding Electrode Assembly Symmetrical Winding Start Point
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Solution Overview
Problem
Conventional electrode assemblies, such as jelly-roll and stack types, face issues with stress accumulation, deformation, and reduced productivity due to complex manufacturing processes, which affect battery performance and safety, especially in large-sized battery modules for devices like electric vehicles.
Innovation Solution
A stack/folding type electrode assembly is developed where full cells with a cathode/separator/anode structure are overlapped with a continuous separator sheet, with a unit electrode or bi-cell at the center acting as the winding start point, allowing for symmetrical arrangement and simplifying the manufacturing process by eliminating the need for alternating electrode orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the jelly-roll type electrode assembly is manufactured by densely winding long-sheet type cathodes and anodes, then the space utilization is improved, but stress accumulates in the electrode assembly during charge and discharge, causing deformation and potential internal short circuits
Solution Approach 1:
The electrode assembly is segmented into multiple discrete full cells (cathode/separator/anode units) that are stacked and folded, rather than using continuous long sheets. This segmentation allows stress to be distributed across multiple independent units, preventing cumulative stress deformation while maintaining high space utilization through compact stacking.
Solution Approach 2:
The invention transitions from the traditional 2D winding approach to a 3D stacked and folded architecture. By stacking full cells in layers and then folding the entire assembly, the design achieves superior space utilization in three dimensions while the layered structure provides stress relief pathways that prevent deformation.
2Ease of manufacture
If the stack type electrode assembly is manufactured by sequentially stacking unit cathodes and anodes, then the manufacturing process is simplified, but additional transfer processes are required and productivity is lowered
Solution Approach 1:
The invention merges the cathode and anode manufacturing into a single full cell unit with the separator already positioned between them. This integration eliminates the need for separate transfer processes for cathodes and anodes, as complete full cells are handled as single units during stacking and folding, thereby simplifying the process and improving productivity.
Solution Approach 2:
The full cells are pre-assembled with cathodes, separators, and anodes configured in the correct sequence before the stacking and folding operations. This preliminary configuration of complete functional units eliminates the need for complex in-line assembly during the main manufacturing process, streamlining production and enhancing efficiency.
3Productivity
If conventional stack/folding type electrode assemblies are manufactured, then productivity is improved, but the manufacturing process requires alternating electrode orientations which increases process complexity
Solution Approach 1:
The invention employs asymmetric full cell design where the cathode and anode are configured in a fixed orientation (cathode/separator/anode sequence) that eliminates the need for alternating orientations during stacking. This asymmetric configuration simplifies the manufacturing process by allowing all full cells to be stacked and folded in the same orientation, reducing process complexity while maintaining high productivity.
Data Source
AI summary
Disclosed herein is an electrode assembly constructed in a structure in which a plurality of electrochemical cells, formed of full cells having a cathode/separator/anode structure, as basic units, are overlapped, and a continuous separator sheet is disposed between the overlapped electrochemical cells, wherein a unit electrode surrounded by the separator sheet is located at a middle of the overlapped electrochemical cells, which is a winding start point, and the full cells disposed above and below the unit electrode are symmetrical to each other about the unit electrode in the direction of electrodes of the full cells. The electrode assembly is manufactured with high productivity while the electrode assembly exhibits performance and safety equal to those of a conventional stack/folding type electrode assembly.