Battery Separator Fault Detection Using Partial Discharge

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Solution Overview

Problem

Existing battery testing methods for separator layers in lithium-ion batteries are costly, time-consuming, and prone to false positives due to high-voltage breakdown testing, which can destroy the separator and fail to detect contamination effectively.

Innovation Solution

A non-invasive method using a voltage source to apply a threshold voltage below the breakdown voltage of the separator, measuring partial discharges caused by contaminants or voids through a current logger, and analyzing the current data to determine the quality of the separator layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high voltage testing method is used to detect contaminants in separator layer, then detection capability is improved, but separator layer is destroyed causing false positives

Engineering Contradiction:

Improvecontaminant detection capabilityVSAvoidfalse positive rate

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies partial discharge testing instead of full breakdown testing. By using voltages below the breakdown threshold (typically 450-500V for separator materials), the method detects contaminants through partial discharges without causing complete separator failure, thus avoiding false positives while maintaining detection capability

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent performs preliminary testing at controlled voltage levels before reaching breakdown conditions. By monitoring partial discharges at sub-breakdown voltages, the method identifies contaminants early in the testing process, preventing the need for destructive full breakdown testing

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If microscopy techniques are used to test separator layer for contaminants, then detection precision is improved, but manufacturing time and cost increase

Engineering Contradiction:

Improvecontaminant detection precisionVSAvoidmanufacturing speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces mechanical microscopy techniques with electrical field-based partial discharge testing. This substitution enables non-contact, rapid detection of contaminants through electrical measurements, significantly reducing testing time and cost while maintaining detection precision

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a simple, inexpensive testing setup involving basic voltage sources and measurement equipment, replacing costly microscopy systems. The method provides adequate detection capability at a fraction of the cost and time required for optical microscopy

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If high voltage breakdown testing is applied to separator layer, then contaminant detection is attempted, but separator layer integrity is compromised

Engineering Contradiction:

Improvecontaminant detectionVSAvoidseparator layer integrity

Core Design Contradiction:

Measurement precisionVSStrength

Solution Approach 1:

The patent applies partial discharge testing at voltages below the breakdown threshold. By using controlled voltage levels (typically 450-500V for separator materials) that induce partial discharges but prevent complete breakdown, the method detects contaminants while preserving separator integrity

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent implements protective measures by limiting test voltages to sub-breakdown levels. This beforehand cushioning prevents the harmful effect of complete separator breakdown while still enabling contaminant detection through partial discharge phenomena

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

This approach provides a less destructive, faster, and more reliable method for identifying contaminants and voids in separator layers, reducing waste and labor costs while improving battery quality and safety.

Implementation Method 1

measuring partial discharges caused by contaminants or voids in the separator layer

Methodology Applied

Scientific EffectPartial discharge: Townsend Discharge

Implementation Method 2

a current logger connected to the second battery electrode, and adapted to measure a current caused by partial discharges

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12553951B2Partial discharge fault detector for battery testing

Publication Date: 2026.02.17 KEYSIGHT TECHNOLOGIES INC

AI summary

An apparatus, a method and a system for testing a battery are disclosed. A voltage source adapted to apply a voltage to an assembly having a first battery electrode, a second battery electrode and a separator layer disposed between the first and second battery electrodes. A current logger is adapted to measure a current caused by partial discharges in the separator layer caused by the contaminants or voids in the separator layer, or at an interface between the first battery electrode and the separator layer, or at an interface between the second battery electrode and the separator layer, or in the separator layer. The voltage is less than a threshold value of a characteristic breakdown voltage of the separator layer.