Curved Pouch Secondary Battery Assembly for Shape Retention
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Solution Overview
Problem
Existing methods struggle to maintain a curved surface with a small curvature radius on secondary batteries due to bonding forces between electrodes and separators, leading to delamination and loss of shape over time.
Innovation Solution
A method involving multiple pressing steps using specialized devices to form and maintain a curved surface on electrode assemblies, followed by accommodation in a pouch-type exterior with a concave cup, and surface leveling to ensure uniform curvature retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a pressing press with a curved surface is used to form a curved shape on the electrode assembly, then the curved shape is formed, but the curved surface cannot be maintained due to bonding forces between the electrode and separator, causing the shape to return to its original state
Solution Approach 1:
A support structure is pre-formed within the electrode assembly before the pressing process. This support structure is positioned to maintain the curved shape, and only after it is in place does the pressing press apply force to form the curved surface. The support structure prevents the electrode and separator from returning to their original bonded state, thereby maintaining the curved shape over time.
Solution Approach 2:
A support structure acts as an intermediary element between the pressing press and the electrode assembly. This support structure receives the pressing force and translates it into a stable curved shape, while also providing internal reinforcement to prevent delamination and shape recovery. The support structure mediates the conflict between the bonding forces trying to restore the original shape and the desired curved configuration.
2Shape
If the radius of curvature of the curved surface is decreased to achieve a tighter curve, then the curved shape becomes more pronounced, but the bonding forces between electrode and separator increase, causing worse delamination and shape maintenance issues
Solution Approach 1:
The support structure is installed before pressing to provide preemptive reinforcement against the increased bonding forces that will occur during tight curvature pressing. This allows the pressing process to achieve a small radius of curvature without the electrode and separator delaminating, as the support structure is already in place to counteract the restoring forces.
Solution Approach 2:
The support structure changes the mechanical parameters of the electrode assembly by providing internal reinforcement. This allows the system to withstand higher stresses associated with small radius of curvature pressing without failing. The support structure effectively increases the strength parameter of the assembly, enabling it to resist the increased bonding forces that occur during tight curvature formation.
3Ease of manufacture
If a curved surface is formed on a stacked type electrode assembly without a support structure, then the pressing process is simple, but the electrode and separator delaminate due to lack of support for maintaining the curved shape
Solution Approach 1:
The support structure is pre-installed within the electrode assembly before the pressing process begins. This preliminary action adds a small step to the manufacturing process, but it prevents delamination and ensures reliable curved shape maintenance. The support structure is positioned in advance to provide exactly where the reinforcement is needed during pressing, making the overall process more reliable despite the additional preparation step.
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 method effectively maintains a curved surface with a curvature radius of 70-150 mm, suitable for VR devices, by minimizing delamination and preserving shape integrity over time.
Implementation Method 1
a first pressing step of pressing the top and bottom surfaces of the electrode assembly by using a first pressing device, on which a curved surface is formed, to form a curved surface
Implementation Method 2
a first pressing step of pressing the top and bottom surfaces of the electrode assembly by using a first pressing device... a temperature of heating the electrode assembly may range of 65° C. to 85° C.
Data Source
AI summary
A method for manufacturing a secondary battery includes an electrode assembly preparation step of preparing an electrode assembly on which flat top and bottom surfaces are formed, a first pressing step of pressing the top and bottom surfaces of the electrode assembly by using a first pressing device, on which a curved surface is formed, to form a curved surface, which has a shape corresponding to that of the curved surface formed on the first pressing device, on each of the top and bottom surfaces of the electrode assembly, an accommodation step of accommodating the electrode assembly in a pouch type exterior in which a cup having a concave shape is formed, and a second pressing step of pressing the curved surfaces of the top and bottom surfaces of the electrode assembly and an outer surface of the pouch type exterior by using a second pressing device.