Wound Electrode Assembly Layout to Reduce Separator Stress
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Solution Overview
Problem
Conventional secondary batteries face stress concentration on separators due to external impacts, leading to potential breakage and short circuits at exposed current collector portions.
Innovation Solution
A secondary battery design with shifted and differently dimensioned insulating members covering exposed portions of the positive electrode, reducing stress concentration on separators by aligning insulating member ends and material layer ends in the circumferential direction, thereby minimizing step portions and improving close contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If insulating member ends are arranged to be aligned in the thickness direction of the positive electrode, then current collection is simplified, but stress concentrates on separator local portions causing breakage risk
Solution Approach 1:
The patent applies asymmetry by intentionally misaligning the insulating member ends relative to each other in the thickness direction of the positive electrode. The first insulating member end is positioned at a different location than the second insulating member end, creating an asymmetric configuration that prevents stress concentration on the separator and eliminates the risk of separator breakage during battery assembly and operation.
Solution Approach 2:
The patent applies local quality by creating different positioning relationships for the insulating member ends with the positive electrode material layer ends. The first insulating member end is positioned differently relative to the first positive electrode material layer end compared to how the second insulating member end is positioned relative to the second positive electrode material layer end. This localized differentiation optimizes both current collection efficiency and separator stress distribution.
2Reliability
If insulating members cover exposed portions completely, then internal short-circuit prevention is improved, but stress concentration occurs on separators
Solution Approach 1:
The asymmetric positioning of insulating member ends in the thickness direction prevents concentrated stress on separator local portions while maintaining adequate coverage of exposed current collector portions. This asymmetry allows the insulating members to fulfill their protective function without creating stress concentration points that would lead to separator breakage.
3Productivity
If exposed portions are provided on current collector, then current collection efficiency is improved, but separator breakage risk increases under external impact
Solution Approach 1:
The patent applies local quality by creating differentiated positioning relationships between insulating members and positive electrode material layers at different locations. The first insulating member end is positioned at a specific relationship to the first positive electrode material layer end, while the second insulating member end is positioned at a different relationship to the second positive electrode material layer end. This localized optimization maintains current collection efficiency while preventing separator stress concentration.
Data Source
AI summary
A secondary battery is provided and including a wound electrode assembly in which a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode are wound; and an electrolyte, the wound electrode assembly and the electrolyte being enclosed in an exterior body, at least the positive electrode including a wound current collector, a first positive electrode material layer and a second positive electrode material layer provided on both surfaces of the current collector, and a pair of exposed portions including a first exposed portion in which one surface of a local portion of the current collector is exposed and a second exposed portion in which the other surface facing the one surface in a thickness direction of the positive electrode is exposed.