Optical Fiber Battery Thermal Runaway Detection

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Solution Overview

Problem

Rechargeable batteries, particularly lithium-ion cells, are prone to thermal runaway due to unstable chemistries, posing risks of property damage and safety hazards, and existing solutions only aim to reduce the likelihood rather than eliminate the possibility of such events.

Innovation Solution

A system utilizing an optical fiber mounted near the battery surface to detect thermal events by monitoring light transmission changes, which can trigger warnings, activate cooling systems, or initiate fire control measures when a thermal event is detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If rechargeable batteries use unstable chemistries for higher capacity, then energy density is improved, but thermal runaway risk increases

Engineering Contradiction:

Improveenergy densityVSAvoidthermal runaway risk

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The optical fiber detection system is installed on the battery surface before thermal runaway occurs, enabling early detection of temperature changes and precursor events. This preliminary monitoring allows for preventive action to be taken before the unstable chemistry leads to thermal runaway, resolving the contradiction by adding safety capability without changing the high-energy chemistry.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If traditional temperature sensors are used to detect thermal events, then detection capability is improved, but response time is insufficient to prevent fire spread

Engineering Contradiction:

Improvethermal event detectionVSAvoidresponse time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The optical fiber detects precursor events and early temperature changes before full thermal runaway occurs, providing earlier warning than traditional sensors. This preliminary detection of incipient thermal events enables faster response time to prevent fire spread to adjacent cells.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces traditional electrical temperature sensors with an optical fiber-based detection system. This substitution uses optical rather than electrical measurement, enabling earlier detection of thermal events through light transmission changes in the optical fiber, which responds to temperature and chemical changes before they reach the threshold of traditional sensors.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If optical fiber is mounted in close proximity to battery surface, then detection sensitivity is improved, but susceptibility to thermal damage increases

Engineering Contradiction:

Improvedetection sensitivityVSAvoidthermal damage to sensor

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The optical fiber acts as an intermediary sensing element that is mounted on the battery surface to detect thermal events. The fiber optic material itself is resistant to thermal damage and electromagnetic interference, allowing it to withstand the harsh environment closer to the battery surface than electrical sensors, thus improving detection sensitivity while maintaining sensor durability.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 system provides early detection of thermal runaway precursors, allowing for timely intervention to minimize damage and prevent the spread of fires within battery packs, enhancing safety and reducing collateral damage.

Implementation Method 1

A source of light is optically coupled to the input facet of the optical fiber and a detector optically coupled to the output facet of the optical fiber. Battery health is determined by monitoring the light transmitted through the optical fiber.

Methodology Applied

Scientific EffectLight transmission: Light

Data Source

PatentUS8092081B2Battery thermal event detection system using an optical fiber

Publication Date: 2012.01.10 TESLA INC

AI summary

A method and apparatus is provided for determining when a battery, or one or more batteries within a battery pack, undergoes an undesired thermal event such as thermal runaway. The system uses an optical fiber mounted in close proximity to, or in contact with, an external surface of the battery or batteries to be monitored. A source of light is optically coupled to the input facet of the optical fiber and a detector optically coupled to the output facet of the optical fiber. Battery health is determined by monitoring the light transmitted through the optical fiber.