Semi-Finished Battery Cell Insulation Testing via Constant Current Voltage Charging
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Solution Overview
Problem
Current methods for testing semi-finished lithium-ion battery cells are inadequate in accurately determining insulation quality due to issues like short circuits caused by material burrs, uneven thickness, and particles, leading to misjudgments and inaccurate assessments.
Innovation Solution
A method involving charging the battery cell with a constant current until a voltage threshold is reached, then switching to constant voltage, and measuring the overall electric quantity charged during a default time period to determine if the insulation between electrodes is poor based on exceeding an electric quantity threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hi-pot test is used for insulation testing, then testing can be performed, but misjudgement occurs due to long energy transition time and considerable capacitor deviation
Solution Approach 1:
The patent changes the testing parameters from traditional hi-pot test to a method using constant current charging followed by constant voltage charging. By measuring the charging time and electric quantity under controlled current and voltage conditions, the method achieves more precise insulation detection without the capacitor deviation issues of traditional hi-pot testing.
Solution Approach 2:
The patent replaces the electrical breakdown-based hi-pot test with an electrochemical charging-based measurement system. Instead of applying high voltage to cause breakdown, the system uses controlled charging processes and measures the resulting electric quantity and time parameters to infer insulation quality.
2Reliability
If insulation film is used to separate anode and cathode, then insulation is provided, but distance shrinkage due to cut burrs, particles or uneven thickness causes short circuit
Solution Approach 1:
The patent performs insulation testing on semi-finished battery cells before final assembly and electrolyte filling. By detecting insulation issues early in the manufacturing process through the charging-based measurement method, defects can be identified and corrected before they cause short circuits in the finished product.
Solution Approach 2:
The testing method uses the battery cell's own electrochemical properties and structure to perform self-diagnosis. The charging process naturally reveals insulation defects through measurements of charging time and electric quantity, eliminating the need for external high-voltage test equipment.
3Measurement precision
If steady state and non-stead state scales are used for determination, then testing is performed, but accurate determination cannot be achieved due to little difference between scales
Solution Approach 1:
The patent transitions from static scale comparison to dynamic measurement by monitoring the charging process over time. By measuring the rate of change of electric quantity during constant current and constant voltage charging phases, the method creates dynamically varying measurement signals that provide clear differentiation between different insulation states.
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 the recognition and quantification of short circuits and internal insulation quality, providing a more accurate and efficient testing process compared to traditional high-pot test methods.
Implementation Method 1
charging the semi-finished battery cell with a constant current when a voltage difference between the first conductor and the second conductor is less than a voltage threshold
Implementation Method 2
charging the semi-finished battery cell with a constant voltage when the voltage difference between the first conductor and the second conductor is equal to or larger than the voltage threshold
Data Source
AI summary
A method is provided for testing a semi-finished battery cell. The semi-finished battery cell is charged with a constant current when a voltage difference between the first conductor and the second conductor is less than a voltage threshold. The semi-finished battery cell is charged with a constant voltage when the voltage difference between the first conductor and the second conductor is equal to or larger than the voltage threshold. An overall electric quantity is obtained after a default time period, wherein the overall electric quantity is an electric quantity charged to the semi-finished battery cell with the constant current during the default time period. Accordingly, an insulation related to electrodes of the semi-finished battery cell is determined as poor when the overall electric quantity is larger than an electric quantity threshold.