Battery Pouch Forming for Stable Corner and Bottom Thickness
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Solution Overview
Problem
Existing methods for forming pouches for rechargeable batteries, particularly those with stacking type electrode assemblies, often fail to securely maintain the thickness of the side wall corner portions and the connected bottom, leading to structural weaknesses and safety concerns.
Innovation Solution
A device comprising a die, a stripper, a reverse punch, and a punch is used to reversely form and then supplement the thickness of the pouch substrate, creating a reverse forming portion with specific stretching regions to ensure stable thickness at the side wall corner and bottom areas, employing a two-step process to enhance structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single-step forming process is used to form the pouch substrate, then the manufacturing process is simple and efficient, but the thickness of the side wall corner portion and the connected bottom cannot be securely maintained
Solution Approach 1:
The forming process is divided into two distinct steps: a first forming process that creates the basic pouch shape, and a second forming process that specifically targets the side wall corner portion and connected bottom to supplement their thickness. This segmentation allows each step to focus on specific requirements, ensuring precise thickness control in critical areas without complicating the entire process unnecessarily.
Solution Approach 2:
The first forming process performs preliminary shaping of the pouch substrate, creating the basic structure and preparing the material for the subsequent second forming process. By performing this preliminary action, the material is pre-positioned and pre-shaped, allowing the second process to focus specifically on thickening critical areas without having to create the entire structure from scratch.
2Strength
If the pouch substrate thickness is increased to ensure structural integrity, then the side wall corner and bottom strength is improved, but the overall pouch size and material consumption increase
Solution Approach 1:
The second forming process applies localized deformation specifically to the side wall corner portion and the connected bottom area, increasing thickness only where structurally critical. This local quality approach ensures that material is added or redistributed precisely where needed for strength, rather than uniformly throughout the entire pouch substrate, thus avoiding unnecessary material consumption.
Solution Approach 2:
The forming processes utilize controlled parameter changes including punch depth (3.5mm to 5.5mm), punching speed, and material tension control to achieve localized thickness supplementation. By adjusting these parameters, the process optimizes material distribution to enhance strength in critical areas without requiring overall increases in substrate thickness or material quantity.
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 solution effectively secures a stable thickness for the side wall corner and bottom portions of the pouch, enhancing the structural integrity and safety of the rechargeable battery, particularly when using stacking type electrode assemblies.
Implementation Method 1
a reverse punch that ascends through the first opening at a side of the first surface of the substrate of the pouch to reversely form the substrate of the pouch and performs primary stretching for a side wall corner portion of the pouch and a portion corresponding to a bottom connected to the side wall corner portion; and a punch that descends through the second opening at a side of the second surface of the substrate of the pouch from an opposite side of the reverse punch to form the substrate of the pouch and supplements a thickness of the side wall corner portion of the pouch and a thickness of the bottom connected to the side wall corner portion when secondary stretching is performed by absorbing the primary stretching
Data Source
AI summary
A rechargeable battery includes a pouch that includes an outer flange disposed at an outer periphery thereof and a forming portion formed by forming with respect to a reverse forming portion; and a stacking type of electrode assembly included in the pouch. The forming portion includes a side wall corner portion connected to the outer flange and a bottom connected to the side wall corner portion, and the bottom includes a round portion connected to the side wall corner portion and a main bottom formed by absorbing the reverse forming portion formed during reverse forming of the pouch.