Rechargeable Battery Screening via Electron Transfer Resistance

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Solution Overview

Problem

Existing methods for determining the state of rechargeable batteries, particularly in detecting the likelihood of micro-short circuits, are inaccurate as they rely on increased AC internal resistance caused by electrolyte depletion, which may not always be present.

Innovation Solution

A method and device that measure electron transfer resistance using AC impedance techniques with non-sinusoidal waves to assess inter-electrode distance and electrolyte sufficiency, comparing the results with predetermined threshold values to determine the likelihood of micro-short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If AC internal resistance measurement is used to detect micro-short circuits, then detection simplicity is improved, but detection accuracy deteriorates because micro-short circuits may form without electrolyte depletion

Engineering Contradiction:
Improvedetection simplicityVSAvoiddetection accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameter from AC internal resistance to electron transfer resistance. This parameter change enables detection of micro-short circuits through inter-electrode distance changes, which is a different physical mechanism from electrolyte depletion detection, thereby improving detection accuracy while maintaining measurement simplicity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the electrical resistance measurement approach with an electron transfer resistance measurement approach. This substitution allows detection based on inter-electrode distance changes rather than electrolyte conductivity changes, resolving the limitation of missing micro-short circuit detection

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

2Device complexity

If only circuit voltage OCV measurement is used, then detection process is simplified, but ability to detect potential micro-short circuits deteriorates

Engineering Contradiction:
Improvedetection process complexityVSAvoidmicro-short circuit detection capability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent introduces electron transfer resistance as an additional measurement parameter beyond circuit voltage OCV. This parameter change enables detection of inter-electrode distance changes that indicate potential micro-short circuits, improving reliability without significantly increasing process complexity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent performs electron transfer resistance measurement as a preliminary check to identify batteries with narrowing inter-electrode distances before they develop actual micro-short circuits. This preliminary detection action allows preventive measures to be taken, improving overall system reliability

Inventive Principle:
Principle #10Preliminary action

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

Accurately identifies batteries prone to micro-short circuits by measuring electron transfer resistance and circuit voltage, ensuring higher accuracy in determining battery state and extending the life of battery packs by using only high-quality modules.

Implementation Method 1

measuring an electron transfer resistance of the rechargeable battery by applying a voltage or current having a predetermined or higher frequency to an electrode system of the rechargeable battery

Methodology Applied
Scientific EffectAC impedance measurement: Electrical Impedance Tomography

Data Source

PatentEP3904895B1Method and device for determining state of rechargeable battery
Publication Date: 2025.08.27 TOYOTA BATTERY CO LTD
  • EP3904895B1 patent drawingFigure 1A~2
  • EP3904895B1 patent drawingFigure 3~5
  • EP3904895B1 patent drawingFigure 6

AI summary

A rechargeable battery state determination method determines whether a rechargeable battery (1) is in a micro-short-circuit-prone state, which is a state that is highly likely to form a micro-short circuit. The rechargeable battery state determination method includes measuring an electron transfer resistance (Rs) of the rechargeable battery by applying a voltage or current having a predetermined or higher frequency to an electrode system (2, 3) of the rechargeable battery (1), determining whether an inter-electrode distance (D) is satisfactory based on a comparison of the measured electron transfer resistance (Rs) of the rechargeable battery (1) with a predetermined lower limit threshold value (Rsmin), in which the determining whether an inter-electrode distance (D) is satisfactory including determining that the inter-electrode distance (D) is satisfactory when the measured electron transfer resistance (Rs) of the rechargeable battery (1) is greater than or equal to the lower limit threshold value (Rsmin), and determining that the rechargeable battery (1) is a conforming piece when the inter-electrode distance (D) is satisfactory.