Battery Calendar Aging Estimation via Reference Model
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for determining calendar aging values of lithium-ion batteries are time-consuming and limited in their ability to cover a broad State of Charge (SOC) and temperature range, making it difficult to accurately estimate capacity fade and power degradation, especially for applications requiring long-term reliability like electric vehicles.
Innovation Solution
A computer-implemented method using a battery-generic reference model to measure and determine calendar aging values for a test cell across various Temperature-State of Charge (T-SOC) value pairs, allowing for efficient and precise estimation of capacity loss and impedance changes, which can be applied to various types of battery cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If storage tests are conducted over months and/or years to determine calendar aging values, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent applies preliminary action by conducting storage tests only for a limited initial period (e.g., first few months) to gather essential aging data, then using this data to predict calendar aging values for the entire battery lifecycle through mathematical models, avoiding the need to wait for complete long-term testing
Solution Approach 2:
The patent creates a mathematical model that copies and extrapolates the aging behavior observed during limited testing periods to predict calendar aging values for the full lifecycle, effectively creating a virtual extension of the physical test results without requiring additional physical testing time
2Loss of time
If storage tests are limited to a few SOCs and/or ambient temperatures to reduce testing time, then loss of time is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent changes the approach from direct measurement at multiple SOC and temperature points to using mathematical transformations and models that can predict aging behavior across the full range of SOC and temperature conditions based on limited measurement data, effectively extending the coverage without additional testing
Solution Approach 2:
The patent transitions from physically measuring aging at discrete SOC and temperature points to using a mathematical model that operates in a transformed parameter space, allowing interpolation and extrapolation across the entire SOC and temperature range through computational rather than physical means
3Device complexity
If only a few SOC points are tested to reduce device complexity, then device complexity is reduced, but adaptability deteriorates
Solution Approach 1:
The patent creates a universal mathematical model that can predict calendar aging across the entire SOC range (0-100%) and temperature range based on data from limited test points, making the testing system adaptable to various operating conditions without requiring separate tests for each condition
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Various examples of the disclosure pertain to determining a set of calendar aging values of a test cell of a rechargeable battery, e.g., LIBs. The set of calendar aging values of the test cell of the rechargeable battery corresponds to a set of Temperature-State of Charge (T-SOC) value pairs. The set of calendar aging values of the test cell of the rechargeable battery is determined based on a battery-generic reference model for calendar aging of a (specific or random) battery cell and on a further set of calendar aging values of the test cell of the rechargeable battery. The further set of calendar aging values is obtained/derived from measurements of the test cell of the rechargeable battery and corresponds to a further set of T-SOC value pairs.