Secondary Battery Foreign Matter Detection via Ion Diffusion
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Solution Overview
Problem
Current methods for testing secondary batteries for foreign matter are inefficient due to nonuniform ion concentration on electrodes, leading to prolonged determination times as they rely on waiting for electrode potential changes to stabilize before measuring voltage drops.
Innovation Solution
A method involving charging the secondary battery in a constant-current constant-voltage mode, followed by discharge or charge in the same mode, and then measuring open circuit voltage before and after standing, with optional heating to promote ion diffusion and reduce nonuniformity, allowing for quicker detection of voltage changes indicative of foreign matter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the secondary battery is charged and then left standing to measure voltage drop for foreign matter detection, then the measurement precision is improved, but the determination time is excessively long due to waiting for electrode potential stabilization
Solution Approach 1:
The patent applies preliminary action by performing charge-discharge cycles before the standing period to pre-uniformize the ion concentration distribution on the electrode surface. This preliminary treatment reduces the subsequent stabilization time required during the standing period, enabling faster foreign matter detection while maintaining measurement precision. The charge-discharge cycles are conducted as a preparatory step before the actual voltage drop measurement.
Solution Approach 2:
The patent changes the parameters of charge-discharge operations (current density, voltage limits, cycle number) to optimize the uniformization of ion concentration distribution. By adjusting these parameters, the electrode potential stabilizes faster during the standing period, reducing the determination time while ensuring accurate foreign matter detection through voltage drop measurement.
2Reliability
If the secondary battery is charged to full charge state and left standing for voltage measurement, then foreign matter detection is enabled, but the ion concentration nonuniformity on electrode surface prolongs the stabilization time
Solution Approach 1:
The patent performs preliminary charge-discharge cycles before the standing period to pre-uniformize the ion concentration distribution. This preliminary action addresses the nonuniformity issue that would otherwise prolong the standing time, enabling the battery to reach stable electrode potential faster while maintaining the reliability of foreign matter detection through subsequent voltage measurement.
Solution Approach 2:
The patent employs continuous charge-discharge cycles to progressively uniformize the ion concentration distribution on the electrode surface. This continuous useful action ensures that the electrode reaches a stable state more quickly, reducing the required standing time while maintaining the reliability of foreign matter detection capability.
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 reduces the time required for ion concentration uniformization, enabling faster detection of voltage changes caused by foreign matter, thus efficiently determining whether a secondary battery is conforming or nonconforming.
Implementation Method 1
a heating step of heating the secondary battery is performed by using heat generated in a heat source. The heating of the secondary battery can promote the diffusion of the ions to reduce the nonuniformity of the ion concentration on the electrode.
Data Source
AI summary
A method of testing a secondary battery includes first to fourth steps. At the first step, the secondary battery after manufacture is charged to a first voltage. At the second step, a second voltage lower than the first voltage is set as a target voltage and discharge or charge is performed in a constant-current constant-voltage mode before the secondary battery is left standing. At the third step, the open circuit voltage of the secondary battery is measured before and after the secondary battery is left standing. At the fourth step, it is determined whether the secondary battery is a conforming item or not based on the difference in the open circuit voltage before and after the secondary battery is left standing.