Wound Cell Electrode Assembly Without Tab Grooves
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Solution Overview
Problem
Current middle-tab cells face issues with lithium precipitation, uneven thickness, and low energy density due to tab groove structures, particularly in narrower cells, leading to poor cycling performance and increased thickness from additional protection layers.
Innovation Solution
The cell design incorporates uncoated foil areas on flat sections of the electrode plates without active substance layers, with tabs connected to these areas, and a single insulation layer to cover burrs, avoiding overlapping grooves and allowing for reduced thickness and increased energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a tab groove structure is provided in the electrode plate to accommodate tabs, then tabs can be fixed and electrical connection is achieved, but lithium precipitation occurs at groove positions and cycling performance deteriorates
Solution Approach 1:
The patent removes the harmful groove structure from the electrode plate and extracts only the essential function of tab fixation. Instead of grooves, the patent uses a flat electrode plate structure where tabs are fixed at the edges without creating localized uncoated areas that cause lithium precipitation.
Solution Approach 2:
The patent converts the potential harm of groove structures by eliminating them entirely and replacing with a flat structure. This prevents lithium precipitation while maintaining tab fixation functionality, thereby improving cycling performance.
2Reliability
If multiple insulation adhesive layers are provided on the anode tab to prevent lithium precipitation, then lithium precipitation is prevented, but the cell thickness increases
Solution Approach 1:
The patent removes the need for multiple insulation adhesive layers by eliminating the groove structure that causes lithium precipitation in the first place. This extracts the harmful element (grooves requiring protection) while preserving the essential function (lithium precipitation prevention).
Solution Approach 2:
Instead of adding protective layers to prevent lithium precipitation (adding solution), the patent inverts the approach by removing the groove structure that causes precipitation (removing the problem source). This reduces cell thickness while maintaining reliability.
3Ease of manufacture
If tab groove positions are arranged in narrow cells, then tabs can be accommodated, but groove positions overlap and cell thickness becomes uneven
Solution Approach 1:
The patent removes the groove structure that causes overlapping issues in narrow cells. By extracting the harmful groove element and replacing it with a flat electrode plate structure, tab accommodation is achieved without creating thickness non-uniformity.
Solution Approach 2:
The patent applies local quality by providing the active substance layer selectively: the electrode plate has a flat structure with active substance layers at specific regions (excluding tab fixation areas), ensuring both uniform thickness and proper tab accommodation.
4Ease of manufacture
If the tab groove width is larger than the fixed end of the tab, then tabs can be fixed, but the uncoated area causes lithium precipitation in corresponding cathode areas
Solution Approach 1:
The patent removes the excessive uncoated area problem by eliminating grooves entirely. The flat electrode plate structure with selectively applied active substance layers ensures tab fixation without creating wide uncoated regions that would cause lithium precipitation in cathode areas.
Solution Approach 2:
The patent applies local quality by precisely controlling where the active substance layer is applied: it is provided on the electrode plate except in specific regions corresponding to tab fixation areas. This localized approach prevents lithium precipitation while maintaining tab fixation functionality.
Data Source
AI summary
A cell includes an electrode assembly. The electrode assembly includes: a first electrode plate including a first current collector, a first active substance layer provided on a surface of the first current collector, and a first uncoated foil area without the first active substance layer; a second electrode plate; and a separator disposed between the first electrode plate and the second electrode plate. The electrode assembly is formed by winding the first electrode plate, the separator, and the second electrode plate in sequence. In a winding direction of the electrode assembly, each layer from the second layer to the second outermost layer of the first electrode plate includes a first flat section, and a first bent section and a second bent section provided on two sides of the first flat section respectively.