Secondary Battery Water Removal via Nonaqueous Immersion
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Solution Overview
Problem
Existing methods for manufacturing lithium ion secondary batteries with nonaqueous electrolyte solutions struggle to maintain low water content in the battery container, leading to increased self-discharge and reduced battery performance.
Innovation Solution
A method involving the immersion of electrode assemblies in a nonaqueous liquid followed by a voltage application treatment to remove water, utilizing a nonaqueous liquid with a fluorine-containing lithium salt like lithium hexafluorophosphate, which reduces water content and produces a reaction product that decreases the electric double layer potential, thereby enhancing battery output and reducing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrode sheets with large surface area are used to increase battery capacity, then the battery can store more energy, but the electrode assembly adsorbs more water which is difficult to remove
Solution Approach 1:
The electrode assembly is immersed in nonaqueous liquid before being placed in the battery container, performing water removal in advance. This preliminary action prevents water from contaminating the battery container and electrolyte solution, resolving the contradiction between using large surface area electrode sheets and controlling water content.
2Reliability
If water content in battery container is kept low to improve battery performance, then self-discharge is reduced and capacity maintenance is improved, but manufacturing becomes more difficult
Solution Approach 1:
Water is extracted from the electrode assembly by immersing it in nonaqueous liquid. This extraction method effectively removes water that would otherwise be difficult to eliminate, achieving low water content in the battery container while maintaining manufacturing feasibility.
Solution Approach 2:
Nonaqueous liquid serves as an intermediary medium to transfer water from the electrode assembly to the battery container in a controlled manner. This mediator enables effective water removal while simplifying the manufacturing process compared to direct drying methods.
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 results in a lithium ion secondary battery with superior output characteristics and capacity maintenance, suitable for use in vehicles, by efficiently minimizing water content within the battery container and improving low-temperature performance.
Implementation Method 1
the electrode sheets have a large surface area. Accordingly, a relatively large quantity of water tends to be adsorbed
Implementation Method 2
utilizing a nonaqueous liquid with a fluorine-containing lithium salt like lithium hexafluorophosphate, which reduces water content and produces a reaction product that decreases the electric double layer potential
Data Source
AI summary
Disclosed is a method for manufacturing a secondary battery (10) containing a nonaqueous electrolyte solution. This method comprises a step (S110) for preparing an electrode assembly (20) having positive and negative electrode sheets (30, 40), a step (S120) for immersing the electrode assembly (20) into a nonaqueous liquid (60), and a step (S130, S140) for placing the electrode assembly (20) after immersion into a battery container (11) together with a nonaqueous electrolyte solution (70). By performing the immersion process, the water content in the electrode assembly (20) moves into the nonaqueous liquid (60).