Secondary Battery Small Short Circuit Detection via Compression
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Solution Overview
Problem
Current methods for detecting small short circuits in secondary batteries are inefficient, requiring long inspection times and struggling to differentiate between normal and defective batteries, especially when foreign matter is present but has not yet caused a significant short circuit.
Innovation Solution
A manufacturing method that involves measuring voltage drop amounts under compression and after compression release to detect small short circuits by comparing the differences in voltage drop patterns, utilizing the unique characteristics of voltage drop amounts ΔV1 and ΔV2 to accurately identify defective batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional voltage inspection or capacity inspection is performed to detect small short circuits, then the inspection process is simple, but the detection accuracy is low and defective batteries are not easily detected
Solution Approach 1:
The patent applies preliminary action by performing compression treatment on the battery before inspection. This compression forces foreign matter between electrodes into contact, creating a small short circuit that would not exist under normal conditions. By doing this beforehand, the subsequent voltage inspection can reliably detect the defect that was hidden before compression.
Solution Approach 2:
The patent changes the physical state parameter by applying compression force to the battery. This mechanical compression alters the spatial relationship between electrodes and foreign matter, forcing contact that creates detectable electrical changes. The parameter change from uncompressed to compressed state enables reliable detection of small short circuits.
2Measurement precision
If charging and discharging is performed repeatedly to form a short circuit path for detection, then the small short circuit can be detected, but the inspection time becomes excessively long
Solution Approach 1:
Instead of performing repeated charging and discharging cycles to create short circuit paths, the patent applies compression force as a preliminary action that directly forces foreign matter into contact with electrodes. This creates the short circuit path immediately without requiring multiple charge-discharge cycles, thereby dramatically reducing inspection time while maintaining detection capability.
Solution Approach 2:
The patent skips the time-consuming process of repeated charging and discharging by directly applying compression force to create the short circuit condition. This rushes through the defect creation process in a single step rather than requiring multiple cycles, achieving the same detection goal much faster.
3Measurement precision
If compression force is applied to force foreign matter into contact with electrodes, then small short circuits are created for detection, but the inspection method becomes more complex requiring compression and release cycles
Solution Approach 1:
The patent makes the battery package serve multiple functions: it acts as both the container for the battery and as the compression application interface. By designing the package with compression application portions, the same structure used for battery containment is also used for applying compression force, eliminating the need for separate compression devices and simplifying the overall system.
Solution Approach 2:
The battery package structure is designed to perform the compression function itself through its inherent structural features (compression application portions). The package serves its own inspection needs by incorporating the means to apply compression force, rather than requiring external specialized equipment. This self-service approach reduces system complexity.
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 method allows for high-accuracy detection of small short circuits, enhancing the reliability of secondary batteries by distinguishing between normal and defective products through the ΔV1/ΔV2 ratio, effectively eliminating defective batteries.
Implementation Method 1
When a normal secondary battery is left after charging, the voltage thereof is gradually dropped due to self-discharge.
Data Source
AI summary
A method of manufacturing for a secondary battery. The secondary battery is configured to include an electrode group in a battery package. The electrode group includes a positive electrode, a negative electrode, and a separator. The manufacturing method includes: (a) measuring a first voltage drop amount of the secondary battery with the passage of time in a state in which a compression force in a direction parallel to a lamination direction of the electrode group is applied to the electrode group via the battery package; (b) measuring a second voltage drop amount of the secondary battery with the passage of time in a state in which the compression force is released; and (c) detecting a small short circuit of the secondary battery by comparing the first voltage drop amount and the second voltage drop amount.