Electrode Assembly Pulse Testing for Separator Micro-Short Detection
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Solution Overview
Problem
Medium-to-large sized rechargeable batteries face issues with microscopic short circuits in separators due to pinholes, leading to electrochemical reactions that can cause salt precipitation and ignition, which existing testing methods struggle to detect effectively.
Innovation Solution
An electrode assembly short-circuit test apparatus and method using continuous pulse application and enhanced surface pressure to press the electrode assembly, employing silicon pads with varying thicknesses and hardnesses to improve detection of micro-short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional testing methods are used on separators with pinholes, then the testing process is simple, but micro-short circuits cannot be detected effectively
Solution Approach 1:
The patent applies periodic pulsed voltage instead of continuous voltage to the electrode assembly. The pulsed voltage is applied in cycles, allowing the system to detect micro-short circuits through cumulative heating effects while avoiding continuous high energy input that could cause false positives or damage the battery components.
Solution Approach 2:
The patent changes the voltage application parameters by using pulsed voltage with specific amplitude, width, and cycle characteristics. This parameter modification enables the detection system to identify micro-short circuits that would be undetectable with conventional continuous voltage testing, improving measurement precision without requiring fundamentally new equipment.
2Measurement precision
If surface pressure is increased to detect micro-short circuits, then detection rate improves, but the risk of causing damage to the electrode assembly increases
Solution Approach 1:
The pulsed voltage application creates periodic stress on the electrode assembly rather than continuous stress. This allows the separator and electrode materials to relax between pulses, preventing cumulative damage while still achieving sufficient heating effect at micro-short circuit locations for detection purposes.
Solution Approach 2:
The patent employs a gradual voltage application approach where the pulsed voltage starts at lower amplitudes and progressively increases. This cushioning approach allows the electrode assembly to adapt to the testing stress, preventing sudden damage while still achieving the necessary detection sensitivity for micro-short circuits.
3Measurement precision
If continuous voltage is applied to test for short circuits, then the testing process is straightforward, but the detection sensitivity for micro-short circuits is insufficient
Solution Approach 1:
The pulsed voltage testing method achieves higher detection sensitivity by applying voltage in concentrated pulses rather than continuous application. The periodic nature allows cumulative heating effects to build up at micro-short circuit locations during the pulse width, enabling detection with shorter overall testing duration compared to continuous voltage methods.
Solution Approach 2:
The patent maintains continuous monitoring and voltage application in a pulsed manner, ensuring that the detection process is ongoing without interruption. The pulsed action continues throughout the testing period, accumulating detection data while maintaining the electrode assembly in a controlled state, thereby achieving both high sensitivity and reasonable testing time.
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 and apparatus significantly enhance the detection rate of micro-short circuits by uniformly applying pressure and continuous pulses, ensuring effective identification and prevention of future issues.
Implementation Method 1
when a current/voltage is applied to the electrode assembly, the lattice at a micro-short circuit site in the separator impacts with electrons and is ionized, and the additionally generated electrons impact with other lattices and become ionized, raising a temperature in a short period of time
Implementation Method 2
detects micro-short circuits in the electrode assembly by improving a surface pressure for pressing the electrode assembly
Data Source
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AI summary
An electrode assembly short-circuit test apparatus for a rechargeable battery, includes: a first plate to press a first side of an electrode assembly, the electrode assembly including a negative electrode, a positive electrode, and a separator between the negative electrode and the positive electrode; a second plate to press a second side of the electrode assembly against the first plate; and a continuous pulser connected to a negative electrode tab and a positive electrode tab of the electrode assembly to apply continuous pulses to the negative electrode tab and the positive electrode tab.