Battery Cell Screening Using OCV Deviation and Charge Transfer Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The activation process for battery safety testing, which includes aging and charge/discharge cycles, is time-consuming and inefficient in detecting defective batteries, typically taking 4 to 10 days.
Innovation Solution
A battery cell inspection apparatus that calculates deviations in open-circuit voltage (OCV) and charge transfer resistance (Rct) values to classify cells into suspect and normal groups, using threshold values to identify defective cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple aging cycles are used to detect defective batteries, then detection accuracy is improved, but testing time increases to 4-10 days
Solution Approach 1:
The patent performs preliminary classification using OCV deviation before conducting time-consuming aging cycles. By calculating dOCV = |OCV(t1) - OCV(t2)| and comparing against threshold D1, the system identifies suspect cells that require full aging testing, while normal cells can be quickly cleared, significantly reducing overall testing time while maintaining detection accuracy
Solution Approach 2:
The patent segments the battery population into three groups based on OCV deviation: normal cells (dOCV < D1), suspect cells (D1 ≤ dOCV < D2), and defective cells (dOCV ≥ D2). This segmentation allows different testing strategies to be applied to different groups, optimizing the balance between detection accuracy and testing efficiency
2Reliability
If rigorous safety testing with multiple aging and charge/discharge cycles is performed, then battery safety is improved, but manufacturing cost and time consumption increase
Solution Approach 1:
The patent implements preliminary OCV deviation measurement and classification before committing batteries to lengthy aging and charge/discharge cycles. This preliminary action filters out obviously normal cells early, allowing them to skip extensive testing, thereby improving manufacturing efficiency while maintaining safety through targeted rigorous testing of suspect cells
Solution Approach 2:
The patent uses OCV deviation (dOCV) as a new diagnostic parameter that correlates with battery defects. By measuring voltage at two different times and calculating the absolute difference, the system creates a simple yet effective parameter that enables rapid preliminary screening, reducing the need for time-consuming traditional aging cycles
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
Reduces the time and cost of safety testing by quickly identifying defective batteries based on OCV and Rct values, improving the efficiency of the activation process.
Implementation Method 1
a sensor configured to obtain an impedance value and at least two open-circuit voltage (OCV) values at different time points for each of a plurality of battery cells
Implementation Method 2
a sensor configured to obtain an impedance value and at least two open-circuit voltage (OCV) values at different time points for each of a plurality of battery cells
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A battery cell inspection apparatus according to an embodiment disclosed in this document may include a sensor configured to obtain an impedance value and at least two open-circuit voltage (OCV) values at different time points for each of a plurality of battery cells, and a processor configured to calculate a deviation (dOCV) between the OCV value at a first time point and the OCV value at a second time point, calculate a charge transfer resistance (Rct) value for each of the battery cells based on the impedance value, classify the battery cells into a suspect group or a normal group based on the deviation, and detect defective battery cells among the suspect group based on the charge transfer resistance value.