Battery Case Sealing for Reduced Internal Pressure
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Solution Overview
Problem
Existing methods for manufacturing nonaqueous electrolyte secondary batteries often result in changes to the electrolyte composition and volume after injection, leading to increased internal pressure and reduced battery performance, particularly due to forced vacuum treatment which can cause vaporization of the solvent and gas formation during initial charging.
Innovation Solution
A method involving placing an electrode assembly in a hermetically sealable battery case and setting the interior in a pressure-reduced state before injecting the nonaqueous electrolyte, then releasing the pressure and sealing the case under atmospheric conditions to maintain a reduced-pressure state within the battery, thereby preventing changes in the electrolyte composition and volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If forced vacuum treatment is applied after electrolyte injection to reduce internal pressure, then the initial internal pressure is reduced, but the solvent vaporizes and electrolyte composition changes
Solution Approach 1:
The battery case is placed in a pressure-reduced state before electrolyte injection, allowing the electrolyte to be introduced under vacuum conditions. The case is then sealed while maintaining the pressure-reduced state, avoiding subsequent vacuum treatment that would cause solvent vaporization and composition changes.
Solution Approach 2:
The hermetically sealable battery case acts as an intermediary container that can be sealed in a pressure-reduced state. This allows the internal pressure to be controlled independently after sealing, enabling pressure reduction without external vacuum treatment that would affect electrolyte composition.
2Stress or pressure
If forced vacuum treatment is applied after electrolyte injection, then internal pressure is reduced, but battery performance degrades due to composition changes
Solution Approach 1:
The battery case is sealed in a pressure-reduced state before electrolyte impregnation is complete, allowing the electrolyte to continue impregnating the electrode assembly after sealing. This preliminary sealing prevents subsequent vacuum treatment and protects battery performance while achieving the desired pressure-reduced state.
3Ease of manufacture
If conventional sealing methods are used after electrolyte injection, then the battery case is sealed, but internal pressure increases due to gas formation and vapor pressure
Solution Approach 1:
The battery case is sealed while in a pressure-reduced state, before gases from self-discharge or electrolyte vaporization can cause pressure buildup. This preliminary sealing under vacuum conditions establishes a low initial pressure that prevents subsequent pressure-related problems during storage and operation.
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 effectively reduces initial internal pressure, minimizes battery performance degradation, and eliminates the need for costly vacuum treatment, while ensuring a sufficient vacuum effect and maintaining battery reliability by preventing gas formation and vaporization, thus enhancing the manufacturing process for nonaqueous electrolyte secondary batteries.
Implementation Method 1
the remaining nonaqueous electrolyte impregnating an interior of the electrode assembly after sealing of the battery case
Implementation Method 2
setting an interior of the battery case in which the electrode assembly has been placed in a pressure-reduced state
Data Source
AI summary
This invention provides a method of manufacturing a nonaqueous electrolyte secondary batteries which includes placing an electrode assembly in a hermetically sealable battery case, injecting a nonaqueous electrolyte into the battery case after the battery case has been set in a pressure-reduced state, and sealing the battery case under atmospheric pressure conditions. Sealing of the battery case is carried out before a given amount of the injected electrolyte completely impregnates the interior of the electrode assembly. As a result, the remaining nonaqueous electrolyte impregnates the interior of the electrode assembly after sealing, thereby making the pressure of voids within the battery case lower than atmospheric pressure.