Cylindrical Electrode Assembly Insulation for Bent Electrode Ends
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Solution Overview
Problem
Cylindrical batteries face issues with internal short circuits due to potential electrical contact between positive and negative electrodes, which can lead to heat generation or explosion, and existing insulation coatings are compromised during bending, increasing internal resistance.
Innovation Solution
An electrode assembly design with uncoated portions and insulation layers that cover specific areas, allowing for bending without damaging the insulation and maintaining electrical separation, along with a gap to prevent contact between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulation coating is applied to electrode ends to prevent electrical contact, then short circuit prevention is improved, but the insulation coating is destroyed or separation film is deformed during bending, curtailing the insulation effect
Solution Approach 1:
The patent applies insulation coating to the electrode ends before the bending process. By performing the insulation coating operation in advance, the coating is already in place and protected during subsequent bending operations, preventing the coating from being destroyed or the separation film from deforming during bending.
Solution Approach 2:
The patent uses a separation film as a flexible insulating barrier between the positive and negative electrodes. This thin film structure provides insulation while accommodating the bending of the electrode assembly, maintaining both the insulation effect and flexibility during the bending process.
2Productivity
If uncoated portions are bent to improve electrolyte impregnability, then electrolyte access is improved, but electrical contact between electrodes may occur reducing safety
Solution Approach 1:
The patent introduces an insulation layer as an intermediary element between the uncoated portions of the positive and negative electrodes. This insulation layer allows the uncoated portions to be bent for improved electrolyte impregnability while simultaneously preventing electrical contact between the electrodes, maintaining both productivity and reliability.
3Use of energy by moving object
If insulation layer is made thinner to reduce resistance, then electrical performance is improved, but insulation effectiveness is reduced
Solution Approach 1:
The patent applies insulation layers selectively at specific locations where electrical contact risk exists, rather than uniformly throughout. This localized insulation approach minimizes the total insulation thickness and associated resistance while maintaining insulation effectiveness at critical points where electrodes may come into contact.
Data Source
AI summary
An electrode assembly in which a first electrode and a second electrode having a sheet shape and a separation film interposed therebetween are wound based on an axis to define a core and an outer circumference is provided. The first electrode and the second electrode respectively includes an uncoated portion not coated with an active material layer on a longer edge end; and a coated portion having an active material layer coated on a region excluding the uncoated portion. The first electrode includes an insulation layer that covers at least a portion of the uncoated portion and at least a portion of the coated portion along a winding direction. The uncoated portion may be bent in a radial direction of the electrode assembly, and the bending point may be spaced apart from the axial end of the insulation layer.