Secondary Battery Cap Plate Pressure Equalization Structure
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Solution Overview
Problem
Secondary batteries face issues with internal pressure buildup due to generated gases, which can hinder the operation of safety-related components and lead to electrolyte leakage, while existing solutions fail to effectively equalize internal and external pressures, maintain a vacuum during assembly, and prevent foreign matter penetration.
Innovation Solution
A secondary battery design incorporating a pressure equalization structure on the cap plate, featuring a throughhole and breathable film, along with a bonding layer and ring member, allows for internal pressure equalization with the external environment, ensuring safe operation and preventing electrolyte leakage through the use of a Gore-Tex laminate or PTFE film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the secondary battery is used for an extended period of time, then internal gases are generated and internal pressure rises, but safety-related components cannot operate properly and electrolyte may leak
Solution Approach 1:
The cap plate is segmented into multiple functional regions: a pressure equalization structure with a throughhole and breathable film for gradual pressure release, and a safety vent for emergency pressure relief. This segmentation allows different safety mechanisms to operate at different pressure levels, ensuring reliable safety component operation throughout extended battery usage.
Solution Approach 2:
A breathable film is introduced as an intermediary element in the pressure equalization structure. The breathable film allows gases to pass through while preventing electrolyte leakage, serving as a mediator that enables pressure equalization without compromising battery containment integrity during extended operation.
2Reliability
If a pressure equalization structure with a throughhole is provided in the cap plate, then internal and external pressures can be equalized, but external foreign matter may penetrate into the battery
Solution Approach 1:
A breathable film is installed within the throughhole of the pressure equalization structure. This flexible thin film allows internal gases to escape to equalize pressure while its selective permeability prevents external foreign matter from penetrating into the battery, resolving the contradiction between pressure equalization and contamination prevention.
Solution Approach 2:
The breathable film functions as a porous material that permits gas molecules to pass through while blocking larger foreign particles. This porous structure enables the pressure equalization function to operate reliably without allowing external contaminants to enter the battery interior.
3Reliability
If the internal pressure rises significantly, then the safety vent ruptures to release pressure, but this may cause electrolyte leakage
Solution Approach 1:
The pressure relief function is segmented into two stages: a pressure equalization structure with a breathable film for gradual, controlled pressure release at lower pressure levels, and a safety vent for emergency pressure relief at higher pressure levels. This segmentation ensures that normal pressure buildup is managed without electrolyte leakage, while still providing safety relief when necessary.
Solution Approach 2:
The pressure equalization structure with the breathable film acts as a beforehand cushioning mechanism that gradually releases internal gases before pressure reaches the critical level that would cause safety vent rupture and electrolyte leakage. This prior cushioning prevents the need for aggressive pressure relief that would compromise battery contents.
4Reliability
If a throughhole is provided in the cap plate for pressure equalization, then internal pressure can be released, but a vacuum cannot be maintained during battery assembly
Solution Approach 1:
The breathable film is preliminarily installed in the throughhole before battery assembly, and its presence allows the throughhole to be sealed temporarily. This preliminary action enables the maintenance of vacuum during assembly operations while preserving the pressure equalization function for later operation during battery use.
Solution Approach 2:
The breathable film serves as an intermediary that can be temporarily sealed to maintain vacuum during assembly, then activated to enable pressure equalization during operation. This intermediary element resolves the contradiction between needing a sealed structure for assembly and needing a pressure-release structure for 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
The solution effectively equalizes internal and external pressures, ensures proper operation of safety components, maintains a vacuum during assembly, and prevents foreign matter ingress, enhancing safety and reliability by allowing controlled gas discharge and preventing electrolyte leakage.
Implementation Method 1
a breathable film bonded to the throughhole
Implementation Method 2
a breathable film closing the throughhole
Data Source
AI summary
Various embodiments of the present invention pertain to a secondary battery, and a technical problem thereof to be solved is providing a secondary battery that is capable of equalizing internal/external pressure. To this end, disclosed in the present invention is a secondary battery comprising: an electrode assembly; a case that accommodates the electrode assembly; a cap plate that seals the case, and that has a safety vent that is ruptured when internal pressure of the case rises; a terminal portion that is electrically connected to the electrode assembly, and that extends outwardly from the cap plate; and a pressure equalization structure that is formed on the cap plate so as to equalize the internal pressure and external pressure of the case.