Lithium-Ion Battery Self-Discharge Screening by Tray-Based Thresholds
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Solution Overview
Problem
Existing self-discharge screening methods for lithium-ion batteries, particularly the fixed K-value method, suffer from poor measurement accuracy in large-scale production due to temperature variations and charge state inconsistencies, leading to inadequate factory quality control.
Innovation Solution
A self-discharge screening method that involves grouping batteries into trays to ensure uniform standing temperature and adjusting charge states, using voltage drop measurements and tailored screening thresholds to identify unqualified batteries, and employing an apparatus with modules for measurement, threshold determination, and screening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If fixed K value screening method is used, then implementation is easy and cost is low, but measurement accuracy is poor
Solution Approach 1:
The patent changes the screening parameter from a fixed K value to a dynamic threshold based on the average voltage drop of the batch. Instead of using a predetermined fixed value, the system calculates the average voltage drop across all batteries in a batch and sets the screening threshold as a multiple (e.g., 1.5 times) of this average. This parameter change allows the screening criterion to adapt to different batches and conditions, significantly improving measurement accuracy while maintaining ease of implementation through automated calculation.
2Productivity
If fixed K value screening method is used, then factory yield is improved, but factory quality is affected
Solution Approach 1:
The patent implements a feedback mechanism where the screening threshold is dynamically adjusted based on the actual performance data of the battery batch being screened. The system measures the voltage drop of each battery, calculates the batch average, and uses this feedback to set the screening threshold. This closed-loop approach ensures that the screening process adapts to the specific characteristics of each batch, maintaining high factory yield while significantly improving factory quality by accurately identifying unqualified batteries based on relative performance rather than absolute fixed criteria.
3Quantity of substance
If batteries are placed in multiple trays for screening, then screening capacity is increased, but temperature uniformity becomes difficult to maintain
Solution Approach 1:
The patent applies segmentation by dividing the battery batch into multiple trays for parallel screening, thereby increasing overall screening capacity. Each tray is treated as an independent unit that can be screened simultaneously. The system calculates the average voltage drop for each tray separately and sets individualized screening thresholds for each tray based on its specific characteristics. This segmentation approach allows the system to handle large quantities of batteries while maintaining accurate screening by accounting for potential temperature variations between different trays through individualized threshold calculation.
Data Source
AI summary
A self-discharge screening method for lithium-ion batteries is provided. In the method, a single batch screening objects includes a plurality of trays. Each tray of the plurality of trays includes a plurality of batteries to be screened. Voltage drops per unit time of the plurality of batteries to be screened are measured. Voltage drop screening thresholds of the plurality of trays are determined according to the measured voltage drops per unit time. Unqualified batteries are screened out according to a relative relationship between the voltage drop screening threshold of the tray and the voltage drops per unit time of the plurality of batteries.