Two-Stage Vacuum Drying for Lithium-Ion Battery Electrode Assemblies
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Solution Overview
Problem
Current methods for drying lithium-ion battery electrode assemblies do not achieve low enough water content, which affects the electrochemical performance and stability of the batteries, and are often costly due to stringent moisture control requirements.
Innovation Solution
A two-stage drying method under vacuum, where the electrode assembly is first dried at a lower temperature (50-90°C) and then at a higher temperature (90-155°C), with repeated cycles of vacuum drying and filling with dry air or inert gas to achieve a water content of less than 20 ppm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-stage vacuum drying is used, then the drying process is simple, but the water content cannot be reduced below 100-500 ppm
Solution Approach 1:
The drying process is divided into multiple stages with different temperature ranges (50-90°C, 90-155°C) and different vacuum pressure levels. Each stage targets specific moisture removal requirements, enabling water content reduction to below 20 ppm while maintaining manageable process complexity through systematic segmentation.
Solution Approach 2:
The drying process employs periodic cycles of vacuum drying followed by dry air or inert gas filling. This periodic action creates favorable conditions for moisture removal during vacuum phases while preventing re-absorption during gas filling phases, achieving ultra-low water content through repeated cyclic treatment.
2Manufacturing precision
If stringent moisture control is implemented throughout production, then water content is reduced, but production cost increases significantly
Solution Approach 1:
Moisture removal is performed as a preliminary action before electrolyte filling, using controlled vacuum drying stages. By removing the majority of moisture beforehand rather than maintaining stringent moisture control throughout the entire production process, the method reduces overall production costs while achieving the required low water content in the final product.
Solution Approach 2:
The method extracts and removes moisture as a separate preliminary step before the main assembly process. By taking out the moisture removal function from the continuous production line and performing it as a dedicated pre-treatment step, the system achieves low water content without requiring expensive moisture control measures during subsequent manufacturing operations.
3Productivity
If high temperature drying is used, then water content is reduced faster, but binder composition and electrode structure are affected
Solution Approach 1:
The temperature profile is segmented into multiple stages (50-90°C, then 90-155°C) rather than applying high temperature uniformly. This segmentation allows gradual moisture removal at lower temperatures first, then more aggressive drying at higher temperatures only after the electrode structure has stabilized, achieving both fast drying speed and structure integrity.
Solution Approach 2:
The drying process uses periodic alternation between vacuum phases (where moisture evaporates) and gas filling phases (where the structure stabilizes). This periodic action allows the electrode to withstand higher temperatures during vacuum phases when moisture removal is most effective, while the gas filling phases provide structural relaxation, maintaining binder integrity throughout the high-temperature drying 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 effectively reduces the water content in lithium-ion battery electrode assemblies to a low level, enhancing electrochemical performance and stability while reducing production costs by allowing for less stringent humidity control during manufacturing.
Implementation Method 1
drying the electrode assembly under vacuum at a temperature from about 50°C to about 90°C
Implementation Method 2
drying the electrode assembly under vacuum at a temperature from about 50°C to about 90°C for a period of time from 5 minutes to 4 hours
Implementation Method 3
further drying the electrode assembly under vacuum at a temperature higher than 90°C; filling the drying chamber with dry air or inert gas; and repeating steps 4) and 5)
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Provided herein is a method of drying an electrode assembly of lithium-ion battery, comprising drying the electrode assembly in two successive stages under vacuum at elevated temperature; filling the oven with hot, dry air or inert gas; repeating the steps of vacuum drying and gas filling several times. The method disclosed herein is particularly suitable for drying electrode assemblies using aqueous binders.