Mandrel Reinforcement for Stable Jellyroll Core Formation
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Solution Overview
Problem
Cylindrical secondary batteries face issues with deformation and collapse of the winding core due to stress accumulation in the hollow space, leading to potential short circuits and tab welding problems during the electrolyte filling process.
Innovation Solution
A mandrel unit with a reinforcement member is used to secure and support the electrode assembly, preventing deformation and collapse by incorporating a shape memory alloy or heat shrinkable tube that surrounds the mandrel, allowing the electrode assembly to slip smoothly during expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a hollow winding core is used in the jellyroll, then the electrode assembly can be wound and formed, but the winding core deforms and collapses due to stress accumulation
Solution Approach 1:
A mandrel unit is introduced as an intermediary tool during the jellyroll formation process. The mandrel provides temporary support to the electrode assembly during winding, preventing deformation of the winding core. After formation, the mandrel is removed, leaving a stable jellyroll structure without the need for a permanent hollow winding core.
Solution Approach 2:
The mandrel is placed in position before the electrode assembly is wound around it. This preliminary action ensures that the winding core maintains its shape during the stress of formation. The mandrel acts as a preliminary support structure that is removed after serving its purpose, preventing both formation of the jellyroll and subsequent deformation.
2Stability of the object's composition
If the winding core is supported during formation, then deformation is prevented, but the structure becomes more complex
Solution Approach 1:
The mandrel is designed as a temporary, disposable support structure that is discarded after serving its purpose during formation. This allows the winding core to be supported during the critical formation process without requiring a permanent, complex support structure. The mandrel is removed after formation, simplifying the final product structure.
3Stability of the object's composition
If the winding core is rigid to prevent deformation, then shape stability is improved, but the electrode assembly cannot expand and contract smoothly
Solution Approach 1:
The solution transitions from a static, permanent winding core to a dynamic, temporary mandrel support system. The mandrel provides rigid support during formation, then is removed to allow the electrode assembly to dynamically expand and contract during operation without a rigid internal structure that would restrict movement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The reinforcement member effectively prevents deformation and collapse of the winding core, reducing the risk of short circuits and ensuring stable tab welding, thereby enhancing the structural integrity of the jellyroll.
Implementation Method 1
A mandrel unit with a reinforcement member is used to secure and support the electrode assembly, preventing deformation and collapse by incorporating a shape memory alloy or heat shrinkable tube that surrounds the mandrel
Implementation Method 2
A mandrel unit with a reinforcement member is used to secure and support the electrode assembly, preventing deformation and collapse by incorporating a shape memory alloy or heat shrinkable tube that surrounds the mandrel
Data Source
AI summary
Disclosed herein are a mandrel unit including a reinforcement member capable of preventing deformation of a jellyroll and reform collapse, a jellyroll forming method, an electrode assembly, and a secondary battery. The mandrel unit includes: a mandrel winding an electrode assembly secured to one region thereof in one direction; and a reinforcement member mounted in one region of the mandrel and securing the electrode assembly to the mandrel.