Electrode Assembly Bi-Cell Monocell Folding Structure
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Solution Overview
Problem
Conventional electrode assemblies, such as jelly-roll and stacked/folded types, face issues with stress accumulation, non-uniformity, and reduced productivity due to complex winding and stacking processes, leading to suboptimal energy density and safety concerns in battery cells.
Innovation Solution
The electrode assembly features a bi-cell and monocells folded on a continuous separation film, where the bi-cell has same-type electrodes and monocells have different electrodes, with monocells being n times the width of the bi-cell, allowing for increased capacity and reduced electrode tabs, enhancing energy density and weldability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If jelly-roll type electrode assembly is used, then battery capacity can be increased, but stress accumulation occurs and electrode assembly may deform
Solution Approach 1:
The electrode assembly is divided into multiple unit cells (monocells) that are stacked and folded together. Each unit cell contains a limited number of electrode sheets (e.g., 3-5 pairs), preventing excessive stress accumulation that occurs in long-sheet wound structures. The segmentation allows stress to be distributed across multiple smaller units rather than concentrating in a single large wound structure.
Solution Approach 2:
Multiple unit cells are nested within a common outer packaging case, with each unit cell containing folded electrode sheets and separators. The unit cells are arranged in a compact nested configuration, allowing the battery to achieve high capacity through multiple stacked units while maintaining structural integrity and preventing deformation through the nested organization.
2Manufacturing precision
If stacked type electrode assembly is used, then manufacturing precision can be improved, but productivity decreases due to complex stacking process
Solution Approach 1:
Electrode sheets and separators are pre-assembled into complete unit cells with proper alignment before stacking. Each unit cell is prepared as a complete, self-contained module with electrodes and separators already positioned correctly, eliminating the need for complex real-time alignment during the stacking process and improving manufacturing efficiency.
Solution Approach 2:
The electrode assembly structure changes from continuous long sheets to discrete unit cells with standardized dimensions. This parameter change allows for easier handling, stacking, and assembly using automated equipment, significantly improving productivity while maintaining precise alignment through the standardized module design.
3Quantity of substance
If number of electrode sheets is increased, then battery capacity increases, but number of electrode tabs increases and welding complexity increases
Solution Approach 1:
Multiple electrode sheets within each unit cell are electrically connected through internal tab arrangements, merging multiple electrode connections into fewer external tabs per unit cell. The folded structure allows electrodes to be connected in series or parallel configurations within the unit cell, reducing the number of external welding points needed while maintaining high capacity through multiple stacked units.
Data Source
AI summary
Disclosed herein is an electrode assembly configured to have a structure in which a bi-cell and two or more monocells are folded in a state in which the bi-cell and the two or more monocells are arranged on a continuous separation film. The bi-cell includes electrodes in the form of at least one cathode and at least one anode stacked so that a separator is disposed between the cathode and the anode, the bi-cell having a first dimension in a first direction substantially equal to w. The two or more monocells each include electrodes in the form of at least one cathode and at least one anode stacked so that a separator is disposed between the cathode and the anode, each cathode and each anode of each monocell having a first dimension in the first direction substantially equal to 2 times the first dimension w of the bi-cell.