Secondary Battery Life Diagnosis via Electrolyte Diffusion Estimation

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Solution Overview

Problem

Existing methods for diagnosing secondary batteries, such as lithium ion batteries, fail to accurately evaluate remaining life due to variations in battery performance despite similar discharge capacity and internal resistance measurements, and require complex simulations and software expertise.

Innovation Solution

A method to estimate electrolyte diffusion coefficient and evaluate remaining life by using trained models based on input data including rated capacity, discharge capacity, voltage drops, temperature rises, and electrode parameters, without disassembling the battery, thereby simplifying the diagnosis process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional diagnosis methods using discharge capacity and internal resistance are used, then the diagnosis process is simple, but the remaining life evaluation accuracy is insufficient

Engineering Contradiction:
Improveremaining life evaluation accuracyVSAvoiddiagnosis process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the diagnostic parameters from conventional discharge capacity and internal resistance to electrolyte diffusion coefficient and its difference from threshold value (ΔD). This parameter transformation enables accurate remaining life evaluation while maintaining diagnostic simplicity, as the trained model automatically processes input data (voltage drops, temperature rises, discharge capacity) to output these predictive parameters without requiring complex simulation operations during actual diagnosis.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary action by training the diagnostic model in advance using simulation data and experimental data. The trained model stores the relationship between battery characteristics and remaining life in its parameters. During actual diagnosis, only simple measurements are needed, and the model automatically outputs accurate predictions without requiring users to perform complex simulations or have specialized knowledge, thus resolving the contradiction between accuracy and complexity.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If simulation methods are used to estimate characteristic values, then the diagnosis accuracy is improved, but the operation complexity and time consumption increase

Engineering Contradiction:
Improvecharacteristic value estimation accuracyVSAvoiddiagnosis operation simplicity
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The patent creates a copied version of the complex simulation process by training an artificial neural network model to replicate the simulation results. Instead of performing actual simulations during diagnosis, the pre-trained model copies the simulation outcomes based on input measurements. This copying approach maintains high accuracy while eliminating the need for users to operate complex simulation software, thus resolving the contradiction between accuracy and ease of operation.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent substitutes the mechanical simulation system with an artificial neural network model. The trained model replaces the need for complex simulation calculations during actual diagnosis, transforming a computationally intensive process into a simple data input-output operation. This substitution maintains estimation accuracy while dramatically improving ease of operation and reducing time consumption.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If only discharge capacity and internal resistance are measured, then the measurement process is simple, but the remaining life prediction accuracy is insufficient

Engineering Contradiction:
Improveremaining life prediction accuracyVSAvoidmeasurement data requirements
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent makes the diagnostic system multi-functional by using a single trained model to process multiple types of input data (voltage drops at different SOC points, temperature rises, discharge capacity) and simultaneously output both electrolyte diffusion coefficient and remaining life prediction. This universal approach achieves high prediction accuracy without requiring separate measurement systems or complex data processing procedures, thus resolving the contradiction between accuracy and data requirements.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4685920A1Secondary battery diagnostic method, secondary battery diagnostic program, and secondary battery diagnostic device
Publication Date: 2026.01.28 MAXELL LTD
  • EP4685920A1 patent drawingFigure 1~2
  • EP4685920A1 patent drawingFigure 3~4
  • EP4685920A1 patent drawingFigure 5~6

AI summary

A method of diagnosing a secondary battery is provided that is capable of estimating, in a simple manner, electrolyte diffusion coefficient, which is one of the characteristic values of a secondary battery (i.e., characteristic parameters), without disassembling the secondary battery. A method of diagnosing a secondary battery includes: estimating an electrolyte diffusion coefficient at a time of diagnosis of a secondary battery being diagnosed, Dn, using a first trained model adapted to estimate the electrolyte diffusion coefficient of the secondary battery based on input data containing the following items, (1) to (6): (1) the rated capacity (initial capacity) of the secondary battery; (2) the discharge capacity measured at a discharge rate equivalent to that for the measurement of the rated capacity; and (3) the magnitude of electric current for measurements of the following items, (4) to (6): (4) the voltage drop as determined at a predetermined period of time from initiation of discharge (or voltage rise as determined at a predetermined period of time from initiation of charge); (5) the voltage drop as determined at a predetermined SOC; and (6) the temperature rise as determined at a predetermined SOC.