Folded Lithium Metal Electrode Assembly for Stress-Stable Stacking
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Solution Overview
Problem
Conventional electrode assemblies face issues with stress accumulation due to electrode expansion and contraction, leading to deformation and internal short circuits, especially when using lithium metal as a negative electrode, and have low productivity due to complex manufacturing processes.
Innovation Solution
A novel stackable-foldable electrode assembly structure with a negative electrode interposed between two separating films, divided into stack and folding portions, and wrapped by non-overlapping wrapping portions to minimize lithium metal processing and improve assembly efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a jelly-roll electrode assembly is wound tightly to create a compact structure, then the battery achieves a cylindrical or elliptical cross-section with high energy density, but stress accumulates during charge and discharge causing electrode deformation and potential internal short circuits
Solution Approach 1:
The electrode assembly is divided into multiple electrode units, each comprising a positive electrode, negative electrode, and separating film. These segmented units are stacked sequentially rather than wound into a tight jelly-roll structure, allowing each unit to expand and contract independently during charge-discharge cycles, thereby reducing stress accumulation and deformation while maintaining compact overall battery design
Solution Approach 2:
The invention transitions from the traditional two-dimensional winding (jelly-roll) approach to a three-dimensional stacked configuration. By stacking electrode units in the thickness direction of the battery, the structure achieves compactness without the severe radial compression stresses that cause deformation in wound designs, effectively distributing mechanical stress across multiple dimensions
2Stability of the object's composition
If a jelly-roll electrode assembly is wound with long sheets of positive and negative electrodes, then the battery achieves continuous electrode structure, but it becomes difficult to maintain constant spacing between electrodes quickly, resulting in decreased productivity
Solution Approach 1:
The continuous electrode structure is segmented into discrete electrode units with predetermined dimensions. Each unit is pre-assembled with fixed spacing between positive and negative electrodes, allowing rapid stacking without the need for complex winding and spacing control mechanisms, thereby maintaining spacing uniformity while significantly improving productivity
Solution Approach 2:
The electrode units are prepared in advance with predetermined spacing and configuration before stacking. This preliminary preparation of modular units with fixed geometry enables quick assembly through simple stacking operations, eliminating the time-consuming winding and spacing adjustment processes required in traditional jelly-roll manufacturing
3Adaptability or versatility
If a stackable electrode assembly uses sequential stacking of multiple positive and negative electrode units, then the battery achieves modular structure, but the separate pole plate transfer process and sequential stacking require a lot of time and effort, resulting in low productivity
Solution Approach 1:
The invention combines the positive electrode, negative electrode, and separating film into a single integrated electrode unit that includes both electrodes and the separating structure. This merging of components into pre-assembled units eliminates the need for separate pole plate transfer processes and reduces the number of sequential stacking steps, thereby maintaining modular adaptability while significantly improving manufacturing efficiency
Data Source
AI summary
An electrode assembly including a negative electrode structure and a plurality of positive electrodes is provided. The negative electrode structure includes first and second separating films, and a negative electrode including a lithium metal layer interposed between the first and second separating films. The negative electrode structure is divided into a plurality of stack portions, a plurality of folding portions, and first and second wrapping portions according to their positions in the electrode assembly. In the negative electrode structure, the plurality of stack portions and the plurality of folding portions are positioned in an alternating manner between the first and second wrapping portions. The electrode assembly has a configuration wherein the exterior in the thickness direction and the longitudinal direction is defined by the first and second wrapping portions, or is defined by the first and second wrapping portions and at least one outermost stack portion.