Secondary Battery Activation for Low-Voltage Defect Detection
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Solution Overview
Problem
Existing methods for detecting low voltage defects in secondary batteries struggle to accurately differentiate between good and defective products due to similar voltage drop amounts, making it difficult to identify and prevent potential failures or damage.
Innovation Solution
A multi-step activation process involving pre-aging, primary charging, high-temperature aging, and room-temperature aging, along with specific charging rates and times, to form a uniform SEI film and stabilize it, reducing the voltage drop in good products and increasing the voltage drop in defective products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional activation process with primary charging to 10-40% SOC and subsequent aging is used, then the process is simple and quick, but the voltage drop amounts of good and defective products overlap making low voltage defect detection inaccurate
Solution Approach 1:
The activation process is divided into multiple distinct stages: pre-aging at room temperature, primary charging to 65-75% SOC, high-temperature aging, and final room-temperature aging with OCV measurement. This segmentation allows each stage to serve a specific function in enhancing defect detection capability while maintaining process manageability.
Solution Approach 2:
The invention changes key process parameters including charging SOC range (65-75% instead of 10-40%), temperature conditions (high-temperature aging followed by room-temperature aging), and measurement timing (OCV measurement after room-temperature aging). These parameter changes maximize the voltage drop difference between good and defective products, achieving detection accuracy improvement.
2Measurement precision
If high temperature aging is applied to accelerate defect detection, then the voltage drop of defective products increases, but the voltage drop of good products also increases reducing detection contrast
Solution Approach 1:
A pre-aging step at room temperature is performed before primary charging to prepare the battery cells. This preliminary action ensures consistent initial conditions for all cells, reducing variability in voltage drop responses and enhancing the reliability of subsequent high-temperature aging results.
Solution Approach 2:
The aging process uses periodic temperature variation: room temperature pre-aging, high-temperature aging, and final room-temperature aging with measurement. This periodic action allows the benefits of high-temperature defect revelation while returning to room temperature for accurate measurement, maintaining product performance stability.
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 method improves the detection power of low voltage defects by ensuring a small average and standard deviation of voltage drop in good products, thereby preventing the distribution and use of defective batteries, reducing the risk of failure, damage, or ignition.
Implementation Method 1
a pre-aging step of aging a secondary battery including a positive electrode containing a positive electrode active material, a negative electrode containing a negative electrode active material, a separator interposed between the positive electrode and the negative electrode, and an electrolyte
Data Source
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AI summary
The present invention relates to a secondary battery activation method comprising: a pre-aging step (S100) for aging, at room temperature, a secondary battery comprising a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, a separator disposed between the positive electrode and the negative electrode, and an electrolyte; a charging step (S200) for primarily charging the pre-aged secondary battery to a secondary battery capacity (SOC) of 60% or more; a high-temperature aging step (S300) for aging the primarily charged secondary battery at a high temperature; and a room-temperature aging step (S400) for aging, at room temperature, the secondary battery which has been aged at a high temperature, wherein the high-temperature aging step is performed at a temperature of 60 °C or higher. The activation method of the present invention has, by uniformly and stably forming a negative electrode SEI film by primary charging and accelerating the stabilization of the SEI film through high-temperature aging to thereby reduce the voltage drops of good products and improve the variation thereof, the effect of enhancing the ability to detect low-voltage defects.