Pouch Cell Vent Pressure Measurement Under Negative Pressure
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Solution Overview
Problem
Conventional methods for measuring the vent pressure of pouch cells in lithium secondary batteries are inaccurate due to deformation and resistance issues when pressurized air is applied, making it difficult to determine the precise venting pressure.
Innovation Solution
An apparatus that uses a negative pressure environment to expand the pouch cell, incorporating a measurement unit and a negative pressure forming unit to minimize internal pressure changes, and includes a system to supply outside air if necessary to induce venting, along with a load sensor and pressure sensitive paper for accurate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressurized air is supplied to induce venting, then venting can be achieved, but measurement accuracy deteriorates due to cell deformation and venting resistance
Solution Approach 1:
Instead of applying positive pressure from outside to induce venting (conventional method), the patent applies negative pressure by evacuating air from the measurement chamber. This reverses the pressure application direction, allowing the pouch cell to expand naturally under its own internal pressure while minimizing external interference and deformation, thereby improving measurement accuracy
Solution Approach 2:
The patent creates a controlled vacuum environment (inert atmosphere) in the measurement chamber using a vacuum pump. This controlled environment eliminates external air pressure interference and allows for more accurate measurement of the pouch cell's vent pressure by providing a stable baseline pressure condition
2Measurement precision
If the pouch cell is expanded by negative pressure, then measurement accuracy improves, but device complexity increases due to additional components
Solution Approach 1:
The measurement chamber serves multiple functions: it acts as both the containment space for the pouch cell and the vacuum chamber for negative pressure application. The vacuum pump system is integrated to both create the negative pressure environment and maintain measurement conditions, reducing the need for separate specialized components
Solution Approach 2:
The patent introduces a measurement chamber as an intermediary environment between the pouch cell and the external atmosphere. This chamber mediates the pressure application by providing a controlled vacuum environment, allowing accurate measurement without direct external pressure interference on the cell
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
Enables precise measurement of vent pressure by minimizing internal pressure fluctuations and ensuring consistent venting, allowing for accurate determination under various temperature conditions.
Implementation Method 1
a negative pressure forming unit connected to the measurement unit, and forming a negative pressure inside the measurement unit
Data Source
AI summary
An apparatus for measuring a vent pressure of a pouch cell includes a pouch cell accommodating an electrode assembly therein, and formed with a heat fusion part on a side thereof; a measurement unit defining therein a space for seating the pouch cell, expanding the pouch cell by a negative pressure formed in the measuring unit, and measuring a vent pressure of the pouch cell; and a negative pressure forming unit connected to the measurement unit, and forming a negative pressure inside the measurement unit.