Wound Electrode Assembly Overhang Layout for Battery Height Uniformity
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Solution Overview
Problem
Existing secondary batteries, particularly cylindrical batteries, face issues with height uniformity of the electrode assembly, which affects capacity uniformity and assembly compatibility with housing, leading to potential lithium plating and reduced energy density.
Innovation Solution
The electrode assembly design includes specific overhang distances and deviations in the negative and positive coated areas, with controlled ranges for Lp and Ln, along with standard deviations in winding turns and separators, to enhance height uniformity and prevent lithium plating, ensuring consistent assembly and improved energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the electrode assembly uses conventional stacking and winding without controlled overhang distances, then the manufacturing process is simpler, but the height uniformity of the electrode assembly deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the overhang distances (Lp: 0.3-1.7mm at upper end, Ln: 0.8-2.2mm at lower end) of the negative coated area relative to the positive coated area. These specific parameter ranges ensure that the electrode assembly maintains consistent height after winding, improving height uniformity without requiring complex additional structures.
2Productivity
If the electrode assembly has poor height uniformity, then the manufacturing process is faster, but the capacity uniformity of the battery deteriorates
Solution Approach 1:
The patent implements preliminary action by pre-controlling the overhang distances of the negative coated area during the electrode assembly manufacturing process. By establishing the correct Lp and Ln values before winding, the electrode assembly automatically achieves uniform height and consistent capacity without requiring additional post-processing or quality adjustment steps, thus maintaining high productivity.
3Reliability
If the electrode assembly lacks controlled overhang distances, then the manufacturing process is more straightforward, but lithium plating occurs reducing safety
Solution Approach 1:
The patent prevents lithium plating by optimizing the overhang distance parameters (Lp: 0.3-1.7mm, Ln: 0.8-2.2mm) of the negative coated area. These parameter changes ensure proper electrolyte distribution and prevent local current density hotspots that cause lithium plating, thereby improving battery safety without requiring complex additional safety structures.
4Adaptability or versatility
If the electrode assembly has inconsistent height, then the manufacturing process is less constrained, but the assembly compatibility with housing deteriorates
Solution Approach 1:
The patent achieves consistent electrode assembly height by controlling the overhang parameters (Lp and Ln) of the negative coated area. This parameter control ensures that all electrode assemblies have uniform dimensions, enabling them to fit standardized housings and improving assembly compatibility without requiring complex adaptive mechanisms.
Data Source
AI summary
A secondary battery is provided, including an electrode assembly which includes a negative pole sheet, a first separator, a positive pole sheet, and a second separator stacked and wound in sequence. The negative pole sheet includes a negative coated area and a negative tab protruding from the negative coated area. The positive pole sheet includes a positive coated area and a positive tab protruding from the positive coated area. The negative tab and the positive tab are respectively located on two opposite sides of the electrode assembly, and a direction from the negative tab to the positive tab is a height direction. Along the height direction, an upper end of the negative coated area overhangs an upper end of the positive coated area. Along a direction away from the height direction, a lower end of the negative coated area overhangs a lower end of the positive coated area.