Pouch Cell Filling via Negative Pressure and Segmented Sealing
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Solution Overview
Problem
Current methods for filling electrochemical energy storage devices like lithium-ion batteries and supercapacitors with electrolyte liquids face challenges such as contamination, gas bubble formation, and inefficient penetration due to high volatility of solvents, leading to reduced performance and safety concerns, especially in large format cells.
Innovation Solution
A method involving a gas-tight sealable chamber with discrete pressure-regulated compartments allows for controlled filling and sealing of pouch cells without forced conveyance, using a connecting line to introduce electrolyte under negative pressure, ensuring hermetic sealing and minimizing contamination and evaporation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filling methods are used to fill electrochemical cells with electrolyte, then filling can be completed, but contamination of the foil bag or working environment occurs and gas bubbles remain inside the bag
Solution Approach 1:
The filling system is divided into separate hermetically sealed compartments: a first compartment for the cell body and a second compartment for electrolyte storage. This segmentation prevents contamination by isolating the filling process from the external environment while eliminating gas bubbles through controlled pressure differentials between compartments.
Solution Approach 2:
A hermetically sealed connecting line acts as an intermediary channel between the two compartments, allowing electrolyte transfer while maintaining isolation. This intermediary structure enables controlled filling without direct exposure to the external environment, preventing both contamination and gas bubble formation.
2Productivity
If forced conveyance is used to fill large format cells, then filling speed improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The system uses self-service filling where pressure differential automatically drives electrolyte flow from the second compartment to the first. No external pumps or forced conveyance devices are needed—the electrolyte fills the cell autonomously based on pressure balance, simplifying the device while maintaining efficiency for large format cells.
Solution Approach 2:
The invention employs pneumatic pressure control through hermetically sealed compartments to regulate electrolyte flow. By controlling pressure differentials between compartments, the system achieves controlled filling without mechanical pumps, reducing device complexity while maintaining productivity for various cell sizes.
3Manufacturing precision
If vacuum filling is used to improve electrolyte penetration, then penetration efficiency improves, but solvent evaporation and contamination of the vacuum chamber occur
Solution Approach 1:
The system maintains an inert or controlled atmosphere within the hermetically sealed compartments during the entire filling process. This prevents solvent evaporation and contamination by isolating the electrolyte from the external environment, eliminating the need for vacuum filling while achieving complete penetration through pressure differential control.
4Reliability
If hermetic sealing is performed before filling, then contamination is prevented, but gas bubbles cannot escape during filling
Solution Approach 1:
The hermetic seal is segmented into two separate compartments rather than one sealed chamber. The first compartment contains the cell body and the second contains electrolyte, allowing each to be sealed independently. This enables hermetic sealing before filling while preventing gas bubble entrapment through controlled pressure equalization between compartments during the filling process.
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 method enables contamination-free, reproducible, and cost-effective filling of electrochemical energy storage devices, ensuring complete penetration of electrolyte into the cell layers without gas bubbles, enhancing mechanical cohesion and electrochemical properties.
Implementation Method 1
The gas-tight chamber is evacuated to a negative pressure... the interior of the pouch cell is drawn into the evacuated state along with the electrolyte liquid in the connecting line
Implementation Method 2
The electrolyte must permeate the entire battery body. This is achieved by the microporosity achieved during the production of the electrode foils by the process control, which the separator must also have. The liquid electrolyte is drawn into the resulting micropores by capillary forces.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a method for filling a battery or storage battery film bag with fluid and closing this bag, said method comprising the steps:• (a) providing a flexible film bag, in the interior of which the solid components (8; 31) of the battery or the storage battery are situated, wherein the film bag, with the exception of a sealable inlet (11, 12) for fluid is tightly closed; • (b) placing the film bag into a chamber (21) that can be closed so as to be gas-tight and closing the chamber so as to be gas-tight; • (c) after step (b), generating a vacuum in the film bag; • (d) connecting the fluid inlet on the film bag in a sealing manner to a fluid source container (17) via a connecting line (14; 29); • (e) after step (d), completely filling the interior of the bag with fluid via the connecting line; and • (f) hermetically closing the film bag by creating a seam (10; 36), wherein either • (i) the seam is created such that in the process the fluid inlet connected to the connecting line is disconnected from the interior of the film bag and the connecting line is subsequently detached from the fluid inlet; or (ii) the seam runs through the connecting line; and • (g) cutting off the film and/or line parts (37) located outside the seam.