Battery Cell Coating for Early Thermal Runaway Detection
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Solution Overview
Problem
Current methods for detecting thermal runaway in battery packs, such as thermocouples and gas sensing, are limited in their ability to provide early detection, with thermocouples being economically and technically infeasible for comprehensive monitoring and gas sensing only detecting thermal runaway after cell ignition, leading to delayed mitigation.
Innovation Solution
A polymer or composite coating applied to battery cells that emits a detectable volatile compound upon heating, allowing for early detection of thermal runaway through gas sensors placed in the headspace or vicinity of the battery pack, providing quicker and more comprehensive detection compared to traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermocouples are used to monitor cell temperature, then thermal runaway detection capability is improved, but system cost and complexity increase significantly
Solution Approach 1:
A coating layer comprising volatile compounds is applied to the battery cell surface as an intermediary substance. When thermal runaway occurs, the coating volatilizes and releases detectable compounds into the headspace, enabling indirect detection of thermal runaway events without requiring direct temperature measurement sensors on each cell.
Solution Approach 2:
The patent replaces the mechanical/physical sensor-based detection system (thermocouples) with a chemical detection system. Instead of using temperature sensors to directly measure cell temperature, the system uses gas sensors to detect volatile compounds released from the coating, substituting a complex mechanical sensing network with simpler chemical sensing.
2Reliability
If thermocouples are deployed on all cell surfaces, then detection coverage is improved, but economic feasibility deteriorates
Solution Approach 1:
The detection function is segmented between two components: (1) a passive coating layer applied to individual cells that provides the sensing function, and (2) a centralized gas sensor system that detects volatile compounds in the headspace. This segmentation allows each cell to have detection capability without requiring expensive active sensors on every cell.
Solution Approach 2:
Instead of placing physical sensors (thermocouples) on every cell, the patent uses a coating composition that replicates the sensing function chemically. The volatile compounds released from the coating create a detectable signal that copies the information that would be obtained from direct temperature measurement, but at much lower cost.
3Reliability
If gas sensors detect CO2 from combustion, then thermal runaway detection is achieved, but detection timing is delayed until after cell ignition
Solution Approach 1:
The coating layer is pre-applied to the battery cells before operation, containing volatile compounds that will be released at specific temperature thresholds. This preliminary preparation ensures that when thermal runaway begins, the detection signal is immediately available in the headspace, providing early warning before combustion occurs and CO2 is generated.
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 at least an order of magnitude quicker detection of thermal runaway, potentially from 10 minutes to 1 minute, with 100% coverage of cells and reduced system integration costs, enhancing safety in large battery packs by allowing for earlier mitigation actions.
Implementation Method 1
said coating selected such that it decomposes at a temperature range useful for said detection and so as to emit a detectable volatile compound
Data Source
AI summary
An early warning detection system for detecting battery thermal runaway in a battery pack or module, said system comprising a coating applied to the outside of one or more battery pack cells, said coating selected such that it decomposes at a temperature range useful for said detection and so as to emit a detectable volatile compound. Also provided is a method for preparing battery cells for use in a detection system, systems and batteries prepared according to the invention and their use in the detection of battery thermal runaway.