Battery Swelling Force Sensing for Accurate SOH Estimation
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Solution Overview
Problem
Existing battery state of health (SOH) monitoring techniques, particularly incremental capacity analysis (ICA) using voltage measurements, are sensitive to noise and require batteries to be discharged to lower state of charge (SOC) ranges, limiting their applicability and frequency of monitoring.
Innovation Solution
The method employs force measurements derived from the swelling of lithium-ion battery electrodes to create incremental capacity curves, reducing noise and allowing SOH monitoring at higher SOC ranges, thereby enabling more frequent and accurate assessments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage measurements are used for incremental capacity analysis, then capacity fading can be detected, but the method is sensitive to noise and requires extensive post processing
Solution Approach 1:
The patent replaces voltage measurements (electrical domain) with force measurements (mechanical domain) for incremental capacity analysis. Force sensors mounted on the battery housing measure swelling forces directly, providing a mechanical signal that is less susceptible to electrical noise and requires minimal post-processing to extract capacity fading information.
Solution Approach 2:
The patent introduces force sensors as an intermediary measurement device that indirectly captures battery degradation through mechanical swelling. Instead of directly measuring electrical properties that are noisy, the force sensors measure mechanical expansion caused by electrode swelling, which correlates with capacity fading but provides a cleaner signal.
2Measurement precision
If voltage-based incremental capacity analysis is used, then SOH monitoring is possible, but batteries must be discharged to lower SOC ranges which limits monitoring frequency
Solution Approach 1:
The patent changes the measurement parameter from voltage to force, which fundamentally alters the characteristics of the incremental capacity curve. Force-based IC curves maintain identifiable peaks across a wider SOC range, particularly in the 60-80% SOC region, allowing SOH monitoring to occur during normal operating conditions without requiring deep discharge cycles.
3Measurement precision
If voltage measurements are used for IC analysis, then capacity fading can be tracked, but extensive post processing is required to extract voltage differential curve shape
Solution Approach 1:
The patent replaces voltage measurements with force measurements, which inherently provide a cleaner signal with less noise. The force-based incremental capacity curves require minimal post-processing because the mechanical swelling signal is more direct and less corrupted by electrical noise, simplifying the extraction of capacity fading information.
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 provides a more accurate and frequent estimation of battery SOH, minimizing noise and enabling pre-failure warnings and anticipated replacement dates, with errors in capacity estimation maintained within acceptable limits.
Implementation Method 1
the electrochemical processes within a battery change with every discharging and charging cycle... measuring a force indicative of swelling within the battery pack
Data Source
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AI summary
There is disclosed an electrical device including a battery, and a battery management system. The battery management system includes a controller in electrical communication with a pressure sensor to monitor the state of health of the battery. The controller applies a method for determining the state of health that uses a non-electrical (mechanical) signal of force measurements combined with incremental capacity analysis to estimate the capacity fading and other health indicators of the battery with better precision than existing methods. The pressure sensor may provide the force measurement signal to the controller, which may determine which incremental capacity curve based on force to use for the particular battery. The controller then executes a program utilizing the data from the pressure sensor and the stored incremental capacity curves based on force to estimate the capacity fading and signal a user with the state of health percentage.