Secondary Battery Inspection Timing for Low-Temperature Output Accuracy
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Solution Overview
Problem
Current low-temperature output inspection methods for secondary batteries face challenges in measurement accuracy due to voltage drop after the formation reaction of the SEI coating is completed, leading to a small reaction resistance and decreased correlation between measured voltage drop and low-temperature output.
Innovation Solution
The inspection method involves charging the secondary battery to a predetermined voltage, calculating the voltage drop during discharge, determining non-defective products based on this measurement, and performing aging after the inspection, ensuring the low-temperature output inspection is conducted before the formation reaction is complete, thereby measuring a larger reaction resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-temperature output inspection is performed after aging step, then inspection can be done on fully formed battery, but measurement accuracy decreases due to small reaction resistance
Solution Approach 1:
The patent applies preliminary action by performing the low-temperature output inspection before the aging step, when the SEI coating formation reaction is still ongoing. This timing ensures that the reaction resistance is sufficiently large to provide accurate voltage drop measurements, while still allowing inspection on a fully formed battery structure.
2Manufacturing precision
If aging is performed after inspection step, then battery reaches final performance state, but correlation between measured voltage drop and low-temperature output decreases
Solution Approach 1:
The inspection is performed preliminarily before aging to capture the voltage drop characteristics when the SEI coating is still forming. This timing creates a strong correlation between the measured voltage drop and the low-temperature output, as the ongoing formation reaction provides measurable resistance characteristics that reflect future battery performance.
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 improves the accuracy of low-temperature output inspection by maintaining a high correlation between reaction resistance and battery output, ensuring reliable measurement and performance assessment.
Implementation Method 1
a charging step of charging an inspection target cell to a predetermined voltage set in advance
Implementation Method 2
a voltage drop amount calculation step of calculating an amount of a voltage drop due to discharge by discharging the inspection target cell at a voltage of not more than the predetermined voltage
Implementation Method 3
since the low-temperature output inspection is performed based on the voltage drop amount obtained before a formation reaction of a SEI coating is completed
Data Source
AI summary
An inspection method of a secondary battery according to the present invention includes: a charging step of charging an inspection target cell to a predetermined voltage set in advance; a voltage drop amount calculation step of calculating an amount of a voltage drop due to discharge by discharging the inspection target cell at a voltage of not more than the predetermined voltage; a non-defective product determination step of determining that the inspection target cell is a non-defective product, when the voltage drop amount is a threshold or less; and an aging step of performing aging after the non-defective product determination step.