Secondary Battery Packaging Bag Arc Regions for Sealing Reliability
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Solution Overview
Problem
Secondary batteries face sealing failures due to inadequate gap sizes between the electrode assembly and the packaging bag, leading to vibration-induced shaking or expansion-induced force transfer, which compromises the integrity of the battery.
Innovation Solution
The design incorporates a packaging bag with specific dimensions and features, including arc regions and connecting portions, to manage the expansion and vibration of the electrode assembly, ensuring a stable sealing performance by optimizing the gap sizes and stress distribution during the thermal compression process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the gap between the electrode assembly and the packaging bag is made small, then the battery energy density is improved, but the sealing reliability deteriorates due to expansion-induced stress
Solution Approach 1:
The patent applies beforehand cushioning by designing the packaging bag with pre-formed arc regions at the sealing portions. These arc regions create a cushioning effect that absorbs expansion stress before it reaches the sealing area. The curved structure allows the packaging bag to deform elastically during electrode assembly expansion, preventing stress concentration at the sealing portions and maintaining sealing reliability even with minimal gap between the electrode assembly and packaging bag.
2Reliability
If the gap between the electrode assembly and the packaging bag is made large, then the sealing reliability is improved, but the battery energy density deteriorates
Solution Approach 1:
The patent applies local quality by differentiating the structural properties of the packaging bag at different locations. The sealing portions are designed with arc regions providing flexibility and stress absorption, while other portions can maintain tighter fit. This localized structural differentiation allows minimal gap overall for high energy density, while the specific sealing areas have enhanced cushioning properties to maintain reliability.
3Quantity of substance
If the packaging bag is made tight around the electrode assembly, then the battery energy density is improved, but the sealing reliability deteriorates due to vibration-induced shaking
Solution Approach 1:
The arc regions at the sealing portions provide beforehand cushioning against vibration-induced shaking. The curved structure creates a buffer zone that absorbs mechanical shocks and vibrations, preventing the electrode assembly from pulling on the sealing portions during battery operation or transport, thus maintaining sealing reliability with tight packaging.
4Reliability
If the packaging bag is made loose around the electrode assembly, then the sealing reliability is improved, but the battery energy density deteriorates
Solution Approach 1:
The packaging bag implements local quality by having different fit characteristics in different regions. The sealing portions with arc regions provide a looser, more flexible fit for reliability, while the main body of the packaging bag maintains a tighter fit around the electrode assembly to maximize energy density. This spatial differentiation of structural properties resolves the contradiction between loose and tight packaging requirements.
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
This approach reduces the risk of sealing failure by minimizing electrode assembly shake and expansion-induced stress, thereby enhancing the overall sealing performance and energy density of the secondary battery.
Implementation Method 1
edges of the packaging bag may be connected in a sealing manner by thermal compression
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Embodiments of the present application disclose a secondary battery including an electrode assembly, a packaging bag and an electrode lead. The packaging bag includes a first packaging film and a second packaging film, the electrode assembly is disposed between the first packaging film and the second packaging film, and the electrode lead is connected to the electrode assembly. The first packaging film and the second packaging bag each include a main body portion, two extending portions and two connecting portions, the main body portion is located on one side of the electrode assembly in a thickness direction, the two connecting portions are respectively located on two sides of the electrode assembly in a transverse direction, and the two extending portions respectively extend from two ends of the main body portion in the transverse direction and are respectively connected to the two connecting portions. Each extending portion includes a first arc region, an inclined region and a second arc region, the first arc region is connected to an end part of the main body portion in the transverse direction, the second arc region is connected to an end part of the connecting portion close to the main body portion in the transverse direction, and the inclined region is connected between the first arc region and the second arc region. The two connecting portions of the first packaging film are respectively connected to the two connecting portions of the second packaging film.