Battery Impedance Spectrum Estimation via Equivalent Circuit Modeling

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Solution Overview

Problem

Existing methods for estimating the impedance spectrum of batteries require disassembling battery packs into cell units, which is destructive and costly, making it difficult to reassemble and increasing costs.

Innovation Solution

A device and method that estimate a cell-unit battery impedance spectrum value from a pack or module-unit battery impedance spectrum measurement value using Electrical Impedance Spectroscopy (EIS) and a battery charging/discharging measurement device, allowing for non-destructive measurement and reassembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If battery packs are disassembled into cell units for impedance spectrum measurement, then measurement accuracy is improved, but device complexity and cost increase due to destructive disassembly and reassembly requirements

Engineering Contradiction:
Improveimpedance spectrum measurement accuracyVSAvoiddisassembly and reassembly complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an equivalent circuit model as an intermediary between the pack-level measurement and cell-level characterization. The model translates macroscopic pack impedance measurements into microscopic cell-level parameters through mathematical relationships, eliminating the need for physical disassembly while maintaining measurement accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a virtual copy of the cell-level impedance characteristics through equivalent circuit modeling. Instead of physically measuring each cell, the system generates a mathematical representation that replicates cell behavior based on pack-level measurements, avoiding destructive disassembly.

Inventive Principle:
Principle #26Copying

2Measurement precision

If battery packs are disassembled into cell units for impedance spectrum measurement, then cell-level impedance data is obtained, but productivity decreases due to time-consuming disassembly and reassembly processes

Engineering Contradiction:
Improvecell-unit impedance measurement accuracyVSAvoidmeasurement efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The equivalent circuit model serves as a mathematical intermediary that directly translates pack-level EIS measurements into cell-level parameters without requiring physical disassembly. This eliminates the time-consuming manual processes while maintaining measurement accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical disassembly process with a mathematical transformation process. Instead of physically separating cells from the pack, the system uses mathematical models to extract cell-level information from pack-level measurements, dramatically improving productivity.

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

3Measurement precision

If battery packs are disassembled into cell units for impedance spectrum measurement, then accurate cell impedance values are obtained, but loss of substance increases due to potential damage to cell leads and welding portions

Engineering Contradiction:
Improveimpedance spectrum measurement accuracyVSAvoidcell lead and welding portion damage
Core Design Contradiction:
Measurement precisionVSLoss of substance

Solution Approach 1:

The equivalent circuit model acts as an intermediary that extracts cell-level information from pack-level measurements without physical contact with cell components. This eliminates the risk of damaging cell leads and welding portions during disassembly while obtaining accurate cell impedance data.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the limitation of pack-level measurement (inability to obtain cell-level data) into a benefit by using the pack-level measurement itself as the source for deriving cell-level parameters through mathematical modeling, avoiding all disassembly-related damages.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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

Enables efficient and cost-effective estimation of battery impedance spectra without disassembling batteries into cell units, facilitating reassembly and reducing costs while maintaining measurement accuracy.

Implementation Method 1

an electrical impedance spectroscopy (EIS) device 1000 measuring an impedance spectrum value of a battery assembly

Methodology Applied
Scientific EffectElectrical Impedance Spectroscopy: Electrical Resistance

Data Source

PatentEP4325231B1Device, method and system for estimating impedance spectrum of battery
Publication Date: 2025.06.18 LG ENERGY SOLUTION LTD
  • EP4325231B1 patent drawingFigure 1
  • EP4325231B1 patent drawingFigure 2
  • EP4325231B1 patent drawingFigure 3~4

AI summary

According to an embodiment and an experimental example of the present invention, disclosed are a device and a method for estimating an impedance spectrum of a battery, and a system including the same, and disclosed are a device and a method for estimating an impedance spectrum of a battery of a high-efficiency and low-cost battery, and a system including the same, which estimate a cell-unit battery impedance spectrum value by acquiring measurement values from an Electrical Impedance Spectroscopy (EIS) device measuring an impedance spectrum value of a pack or module-unit battery assembly and a battery charging/discharging measurement device measuring a specific parameter value by charging or discharging by applying pulse current to the pack or module-unit battery assembly to facilitate reassembly and reduce cost by enabling non-destruction measurement without the battery into the cell unit.