Battery Deterioration Estimation Using Resistance Aging Corrections

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Solution Overview

Problem

Existing methods for estimating the deterioration degree of lithium ion secondary batteries using internal resistance alone result in low estimation accuracy.

Innovation Solution

A deterioration degree estimation device and method that monitor both cycle and storage deterioration, calculating the deterioration degree based on the increase rate of internal resistance, with corrections applied according to the usage patterns and conditions of the battery, such as current integration value, temperature, and State of Charge (SOC), to enhance estimation accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If only internal resistance is used to determine deterioration degree, then the method is simple, but the estimation accuracy is low

Engineering Contradiction:
Improvedeterioration degree estimation accuracyVSAvoiddetermination method complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple deterioration indicators (internal resistance, cycle deterioration, storage deterioration) into a unified deterioration degree estimation. By merging these different aspects of battery degradation, the system achieves more accurate estimation than using any single indicator alone, while maintaining manageable system complexity through integrated processing.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces additional parameters (cycle deterioration count, storage time) beyond the basic internal resistance measurement. By changing from a single-parameter to multi-parameter approach, the estimation accuracy improves significantly. The system dynamically adjusts the deterioration degree calculation based on these multiple varying parameters.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If cycle deterioration and storage deterioration are monitored, then the estimation accuracy increases, but the monitoring complexity increases

Engineering Contradiction:
Improvedeterioration degree estimation accuracyVSAvoiddeterioration monitoring difficulty
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments battery deterioration into two distinct components: cycle deterioration (from charging/discharging) and storage deterioration (from time-based aging). By dividing the overall deterioration process into these separable segments, the system can monitor and calculate each independently using different methods, then combine them for the final estimation. This segmentation makes the complex monitoring task more manageable.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses internal resistance as an intermediary parameter that reflects both cycle and storage deterioration. Instead of directly measuring complex deterioration mechanisms, the system uses internal resistance changes as a mediator that captures the cumulative effect of both deterioration types, simplifying the detection process while maintaining accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3343689B1Deterioration degree estimation device and deterioration degree estimation method
Publication Date: 2024.02.14 NISSAN MOTOR CO LTD
  • EP3343689B1 patent drawingFigure 1
  • EP3343689B1 patent drawingFigure 2
  • EP3343689B1 patent drawingFigure 3

AI summary

An internal resistance detection unit for detecting the internal resistance of the battery; a deterioration management unit for managing at least one of a battery cycle deterioration and a battery storage deterioration; and a deterioration degree estimation unit for estimating, on the basis of the increase rate of the internal resistance, the deterioration degree of the battery as the estimated deterioration degree are provided, wherein the deterioration degree estimation unit causes the estimated deterioration degree to be smaller as the cycle deterioration becomes larger, if the deterioration management unit is managing the cycle deterioration, and causes the estimated deterioration degree to be larger as the storage deterioration becomes larger, if the deterioration management unit is managing the storage deterioration.