Cylindrical Battery Winding Insulation for Uncoated Tab Short Prevention
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Solution Overview
Problem
Cylindrical secondary batteries face the risk of short circuits due to expansion or movement of the negative electrode mixture portion, which can occur during repeated charging and discharging, leading to potential contact between the positive and negative electrode uncoated portions.
Innovation Solution
An insulating part is applied to the cutting area formed by removing portions of the first and second uncoated areas adjacent to the center of the winding, using an insulative material to prevent contact between the positive and negative electrode uncoated portions, with a thickness of 0.1 to 0.7 mm and a circular ring shape, and integrated into the battery structure to enhance insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no insulating part is provided in the cutting area, then the battery structure is simpler and manufacturing is easier, but short circuit may occur between the positive electrode uncoated portion and the negative electrode mixture portion due to expansion or movement of the negative electrode mixture portion
Solution Approach 1:
An insulating part is introduced as an intermediary element between the positive electrode uncoated portion and the negative electrode mixture portion. This insulating part, formed by applying insulative material to the cutting area, acts as a mediator that prevents direct contact and potential short circuit between the positive and negative electrodes, while allowing the battery to maintain its functional requirements.
Solution Approach 2:
The insulating part is formed in advance during the manufacturing process by applying insulative material to the cutting area before the battery is assembled and put into service. This preliminary application of insulation ensures that the protective function is already in place before any expansion or movement of the negative electrode mixture portion can occur, preventing short circuit proactively rather than reactively.
2Reliability
If the insulative material thickness is increased to ensure insulation, then short circuit prevention is improved, but the battery volume increases and capacity is reduced
Solution Approach 1:
Instead of uniformly increasing insulation thickness throughout the battery, the insulative material is applied locally only to the cutting area where the positive electrode uncoated portion is exposed. This localized application provides insulation exactly where needed to prevent short circuit, while minimizing the overall volume of insulative material and preserving maximum battery capacity.
Solution Approach 2:
The insulative material is applied with a thickness of 0.1 to 0.7 mm, which is sufficient to provide effective insulation in the critical cutting area without excessive material usage. This partial action approach applies insulation only to the extent necessary for safety, rather than uniformly throughout the entire battery structure, thereby optimizing the balance between reliability and capacity.
3Reliability
If the insulating part is applied to the cutting area, then short circuit prevention is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The formation of the insulating part is merged with the existing cutting process. The insulative material is applied to the cutting area in an integrated manner that combines the cutting and insulation steps, reducing the need for separate, complex insulation application processes and simplifying the overall manufacturing workflow.
Solution Approach 2:
The insulative material is applied with controlled parameters (thickness of 0.1 to 0.7 mm, radial distance of 2 to 5 mm from the center of the winding) that can be precisely managed during manufacturing. These defined parameters allow for consistent and reliable insulation application without requiring complex process control, making the manufacturing process manageable and scalable.
Data Source
AI summary
Disclosed is a cylindrical secondary battery including an electrode assembly including a first electrode plate having a first active material layer and a first uncoated portion free of the first active material layer, a second electrode plate having a second active material layer and a second uncoated portion free of the second active material layer, and a separator interposed between the first electrode plate and the second electrode plate, the electrode assembly being wound in a cylindrical shape to form a winding, an insulating part provided on one side of each of the first and second uncoated portions, a cylindrical can accommodating the electrode assembly, and a cap assembly coupled to one side of the can. A part of each of the first and second uncoated portions adjacent to the center of the winding is removed to form a cutting area. The insulating part is provided in the cutting area.