Secondary Battery Swelling Measurement Using Movable Jig
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Solution Overview
Problem
The challenge is to accurately predict and measure the swelling characteristics of secondary batteries, particularly in pouch-type batteries, which can lead to structural instability in battery modules due to increased internal pressure and volume expansion during degradation.
Innovation Solution
A secondary battery evaluation apparatus comprising a fixed jig to restrict swelling and measure reaction force, a variable jig to allow swelling and measure reaction force and thickness change, and a deriving unit to establish the relationship between thickness change and reaction force, enabling effective deformation characterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If pouch-type secondary batteries are used to increase capacity and power in battery packs, then ease of stacking and lightweight advantages are achieved, but structural rigidity is reduced leading to severe swelling phenomenon
Solution Approach 1:
The patent applies dynamics by making the upper jig movable rather than fixed. The upper jig can move in the thickness direction of the battery to accommodate swelling while maintaining contact pressure. This dynamic adjustment allows the testing apparatus to adapt to battery expansion during degradation, enabling accurate measurement of reaction force without compromising the lightweight pouch battery structure.
2Measurement precision
If swelling measurement is performed without restricting swelling, then accurate deformation measurement is achieved, but reaction force measurement becomes difficult
Solution Approach 1:
The patent introduces an elastic member as an intermediary between the movable upper jig and the battery. This elastic member transmits the reaction force from the battery to the jig while allowing the jig to move with the battery's swelling. The elastic member acts as a mediator that enables simultaneous measurement of both deformation (through jig displacement) and reaction force (through force sensor), resolving the contradiction between accurate deformation measurement and reaction force measurement.
3Reliability
If internal pressure increases due to gas generation during battery degradation, then swelling phenomenon occurs, but structural stability of battery module deteriorates
Solution Approach 1:
The patent replaces direct mechanical constraint with a movable jig system that uses elastic members to measure swelling. Instead of rigidly constraining the battery (which would prevent natural swelling and give inaccurate readings), the system allows mechanical movement while measuring the forces involved. This substitution enables accurate characterization of swelling behavior to predict and prevent structural stability issues in battery modules.
4Force
If fixed jig is used to measure reaction force, then force measurement is achieved, but swelling restriction interferes with natural deformation
Solution Approach 1:
The patent transforms the fixed jig into a movable jig that can dynamically adjust its position in the thickness direction of the battery. This dynamic capability allows the jig to follow the battery's natural swelling deformation while maintaining contact for force measurement. The movable design eliminates the interference caused by fixed constraint, enabling simultaneous accurate measurement of both reaction force and swelling deformation.
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 solution allows for accurate measurement of deformation caused by battery degradation, determining the relationship between deformation and reaction force, and estimating the structural stiffness required to prevent swelling, thereby enhancing the design and stability of battery modules.
Implementation Method 1
an elastic member coupled to the variable upper jig to give a restoring force in a direction opposite to the movement of the variable upper jig
Data Source
AI summary
Disclosed is an apparatus capable of effectively and accurately predicting a deformation characteristic in relation to swelling of a secondary battery. The secondary battery evaluation apparatus includes a fixed jig configured to hold a first secondary battery and restrict swelling of the held first secondary battery, the fixed jig measuring a change in a first reaction force of the first secondary battery according to charging and discharging cycles; a variable jig configured to hold a second secondary battery and allow swelling of the held second secondary battery, the variable jig measuring a second reaction force and a first thickness change amount of the second secondary battery according to charging and discharging cycles; and a deriving unit configured to derive a relationship between the first reaction force measured by the fixed jig and the second reaction force and the first thickness change amount measured by the variable jig.