Freeze-Drying Lithium-Ion Electrode Pairs to Reduce Drying Time
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Solution Overview
Problem
Conventional drying methods for lithium-ion secondary batteries, electric double-layer capacitors, and lithium-ion capacitors require long hours, leading to high costs and the risk of creases in separators, which decreases yield and increases manufacturing costs.
Innovation Solution
A method using freeze-drying to reduce drying time and prevent creases in separators by freezing the electrode pairs and other elements, then subjecting them to high vacuum and controlled heat for sublimation, allowing for faster and more efficient moisture removal at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional vacuum drying is used to remove moisture from electrodes, then moisture removal is achieved, but drying time becomes excessively long (5-20 hours for electrodes, 5-24 hours for electrode pairs)
Solution Approach 1:
The patent applies freeze-drying technology which utilizes phase transition of water from solid (frozen state) directly to gas (sublimation) under vacuum conditions. The electrodes are frozen first, then dried under vacuum to enable sublimation of ice, dramatically reducing drying time from 5-20 hours to 1-3 hours while effectively removing moisture.
Solution Approach 2:
The invention changes the temperature parameter from conventional room temperature or heated drying to sub-zero freezing temperature, followed by controlled heating during sublimation. This parameter change enables the use of freeze-drying technology to achieve rapid moisture removal without excessive drying time.
2Productivity
If high temperature drying is used to reduce drying time, then drying speed increases, but creases occur in the separator
Solution Approach 1:
Freeze-drying uses sublimation (solid to gas phase transition) instead of conventional evaporation (liquid to gas). This phase transition occurs at low temperatures under vacuum, enabling rapid moisture removal without subjecting the separator to high temperatures that would cause creases and deformation.
Solution Approach 2:
The invention replaces the thermal-mechanical drying process (heating and air flow) with a vacuum-sublimation process. This substitution eliminates the mechanical stress and high temperature exposure that cause separator creases, while achieving faster drying through direct sublimation of frozen moisture.
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 significantly reduces manufacturing costs and improves yield by shortening drying time and minimizing separator damage, resulting in a more efficient and cost-effective production process.
Implementation Method 1
at least one of (i) drying at least one of the positive electrode(s) and the negative electrode(s) by use of a freeze-drying method and (ii) drying the container in which the electrode pair(s) has been accommodated by use of the freeze-drying method
Implementation Method 2
freezing the electrode pairs and other elements, then subjecting them to high vacuum and controlled heat for sublimation
Data Source
AI summary
A method for drying an electrode pair is disclosed. In at least one embodiment, the method includes preparing a positive electrode by applying a positive electrode material to a current collector; preparing a negative electrode by applying a negative electrode material to a current collector; preparing one set of an electrode pair made up of a positive electrode, a separator, and a negative electrode which are laminated in this order or preparing sets of electrode pairs, the sets being laminated, a separator being provided between the respective sets, each of the electrode pairs being made up of a positive electrode, a separator, and a negative electrode which are laminated in this order; accommodating the electrode pair(s) in a container; and drying the container in which the electrode pair(s) has been accommodated by use of the freeze-drying method.