Battery Module Passive Discharge for Thermal Runaway Containment

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Solution Overview

Problem

Thermal runaway in battery modules, particularly in aviation applications, is a significant safety concern as existing solutions fail to prevent the propagation of thermal events triggered by external heating sources, leading to potential cascading failures.

Innovation Solution

A battery module with a passive control system comprising a thermal switch and load resistor, which rapidly discharges cells to a state-of-charge below 25% when a temperature threshold is exceeded, preventing exothermic reactions and reducing the risk of thermal runaway propagation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a battery module uses existing thermal protection solutions, then some thermal events may be detected, but thermal runaway propagation triggered by external heating sources cannot be prevented

Engineering Contradiction:

Improvethermal runaway preventionVSAvoidthermal event propagation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements preliminary action by discharging cells to a low state-of-charge (below 25%) before thermal runaway can propagate. The passive control system proactively reduces the energy available for exothermic reactions by triggering discharge when temperature thresholds are exceeded, preventing the chain reaction that would otherwise occur during thermal events.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful effect of external heating into a beneficial trigger mechanism. The external heat source that would normally cause thermal runaway instead activates the passive control system, which then discharges the cells to prevent the runaway. The harmful thermal event becomes the activation signal for the protection mechanism.

Inventive Principle:

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

2Object-affected harmful factors

If cells are rapidly discharged to prevent thermal runaway, then exothermic reactions are reduced, but the control system complexity increases

Engineering Contradiction:

Improveexothermic reactionsVSAvoidcontrol system

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent implements self-service through a passive control system that automatically triggers cell discharge without requiring external intervention or complex monitoring. The system uses inherent thermal characteristics (temperature thresholds) to activate the discharge mechanism, making the protection self-regulating and eliminating the need for sophisticated control electronics or continuous monitoring systems.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the operational parameter of cell state-of-charge dynamically based on temperature conditions. Under normal conditions, cells operate at their normal charge levels. When temperature exceeds predetermined thresholds, the system changes the state-of-charge parameter to below 25%, thereby altering the thermal characteristics of the cells to prevent runaway while maintaining simplicity in control implementation.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If all cells are discharged to prevent thermal propagation, then safety is improved, but energy availability for operation is reduced

Engineering Contradiction:

Improvesafety during thermal eventsVSAvoidenergy availability

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies partial action by discharging only to a low state-of-charge (below 25%) rather than completely depleting the cells. This partial discharge is sufficient to prevent exothermic reactions and thermal runaway propagation, while still retaining some energy in the cells for operational use. The discharge level is optimized to provide just enough protection without unnecessarily sacrificing all energy availability.

Inventive Principle:

Principle #16Partial or excessive 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

The solution effectively mitigates thermal runaway by rapidly discharging cells, reducing the risk of exothermic reactions and preventing the spread of thermal events to adjacent cells, thereby ensuring safety standards for aviation applications.

Implementation Method 1

gradually applying heat to the battery module via the external heating source... a cell in the plurality of cells that exceeds a temperature threshold

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

rapidly discharging power in the cell to the resistive load

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS20240162513A1Systems and methods for mechanical prevention of thermal runaway propagation

Publication Date: 2024.05.16 ELECTRIC POWER SYSTEMS INC

AI summary

A method of validating a battery module for flight can comprise: coupling an external heating source to the battery module, the battery module including a plurality of cells; gradually applying heat to the battery module via the external heating source, wherein a cell in the plurality of cells that exceeds a temperature threshold is rapidly discharged to a state-of-charge between 0% and 25%; and verifying no fragments and no flames are released outside the battery module.