Battery thermal events in electric vehicles begin with subtle chemical changes that produce trace gases well before temperature increases become detectable. Current data shows that early-stage cell degradation can release diagnostic gases like CO, CO2, and H2 at concentrations as low as 10-100 ppm, providing a critical window for intervention before thermal runaway occurs.

The engineering challenge centers on developing sensing systems that can reliably detect and differentiate between normal off-gassing during operation and the specific gas signatures that indicate impending cell failure—all while operating in the demanding automotive environment.

This page brings together solutions from recent research—including selective gas sensor arrays, aspiration-based multipoint monitoring systems, impedance-based diagnostic methods, and active thermal control mechanisms. These and other approaches focus on early detection and automated response to prevent cascade failures in EV battery packs.

1. Proactive Multisensory Solution for Mitigating Thermal Runaway Risks in Li-Ion Batteries

uladzimir fiadosenka, linxi dong, chenxi yue - Belarusian State University of Informatics and Radioelectronics, 2025

The paper presents the concept and modeling results of a multisensor system designed to prevent thermal runaway in lithium-ion batteries. This is especially true for LCO, NMC NCO integrates three types sensors: capacitive pressure sensor, gas sensor based on metal oxide semiconductor, platinum temperature sensor. Moreover, all sensors are located single chip, which ensures increased reliability safety, minimizing risks fire, explosion, or damage Three battery operating modes proposed: normal, hazardous, critical. In normal mode, concentration remain at safe levels, while hazardous they begin increase, indicating possible onset destructive reactions. critical reaches can lead damage, explosion. was modeled using COMSOL Multiphysics 6.1 package finite element method. approach helps improve safety batteries by solving problems monitoring their condition. scalability makes it suitable applications both portable electronics electric vehicles.

2. Device with Annular Flow Path and Inner-Outer Electrode Configuration for Measuring Fluid Aeration via Electrical Properties

SOUTHWEST RESEARCH INSTITUTE, 2025

A device and method for measuring fluid aeration in applications like electric vehicle fluids by evaluating electrical properties like conductivity or capacitance. The device has inner and outer electrodes enclosing an annular flow path between them. The electrode sizes and flow control ensure consistent fluid velocity and cross-sectional area through the annular path. This allows accurate measurement of electrical properties to determine aeration levels.

US2025123230A1-patent-drawing

3. Battery Leakage Inspection System with Sealing Box and Switchable Component Connectivity

WUXI LEAD INTELLIGENT EQUIPMENT CO LTD, 2025

A leakage inspection system for batteries with high efficiency and reduced reset time. The system uses a sealing box to contain the battery during inspection. Multiple inspecting components, like detectors, are connected to the box. They can be switched between communication with the box cavity, inspecting mode, and disconnected mode. This allows the components to be quickly swapped out between inspections without waiting for residual gas to dissipate. The box can also be moved between sealing and inspection positions using a rack and lift mechanism. This enables efficient workflow by avoiding long reset times.

4. Battery Module with Fluid Conductivity Sensor for Early Thermal Runaway Detection

PLASTIC OMNIUM CLEAN ENERGY SYSTEMS RESEARCH, 2025

Battery module for a vehicle that can detect thermal runaway early to prevent spread and fires. The battery module has a fluid monitoring device inside the housing to detect pollution fluids escaping from cells. It uses an electrical conductivity sensor to measure changes in the fluid conductivity caused by escaped cell fluids. If conductivity spikes, it indicates a cell failure and triggers selective thermal regulation to isolate and prevent spread. This allows diagnosing cell failures early without temperature sensors on each cell.

5. Battery Housing Pressure Monitoring System for Early Detection of Thermal Runaway in Electric Vehicle Cells

VITESCO TECHNOLOGIES GMBH, 2025

Early detection of battery cell thermal runaway in electric vehicle traction batteries to prevent fires and explosions. The method involves monitoring the internal pressure of the battery housing using a pressure sensor. Thermal runaway in the cells generates gas, causing pressure to rise. By continuously monitoring pressure and comparing against thresholds, runaway can be detected early before excessive gas generation. This allows proactive intervention to prevent catastrophic failure.

6. Operando monitoring of gassing dynamics in lithium-ion batteries with optical fiber photothermal spectroscopy

tianye zheng, haihong bao, feifan chen, 2025

Gaseous molecules are an inherent byproduct of (electro-)chemical reactions in lithium-ion battery cells during both formation cycles and long-term operation. While monitoring gas evolution can help understand chemistry predict performance, the complex nature dynamics makes conventional mass spectrometry approaches insufficient for real-time detection. Here, we present a radically different methodology operando analysis batteries using optical fiber photothermal spectroscopy. By placing hollow-core inside cell, evolved gases rapidly diffuse into hollow core fiber, enabling spectroscopy which precisely selectively quantifies their concentrations without altering internal operation cell. This approach facilitates identification individual gaseous species, thereby reaction pathways. Collectively, show that evolutions C2H4 CO2 closely associated with solid electrolyte interphase, selection salts, inclusion specific additives. Significantly, confirm first time spontaneous CO2, occurs exclusively presence LiPF6 salt. Beyond scope batteries, presented here offers substantial potential broad... Read More

7. Gas Generation in Lithium-Ion Batteries: Mechanisms, Failure Pathways, and Thermal Safety Implications

tianyu gong, xixin duan, yan shan - Multidisciplinary Digital Publishing Institute, 2025

Gas evolution in lithium-ion batteries represents a pivotal yet underaddressed concern, significantly compromising long-term cyclability and safety through complex interfacial dynamics material degradation across both normal operation extreme thermal scenarios. While extensive research has focused on isolated gas generation mechanisms specific components, critical knowledge gaps persist understanding cross-component interactions the cascading failure pathways it induced. This review systematically decouples at cathodes (e.g., lattice oxygen-driven CO2/CO high-nickel layered oxides), anodes stress-triggered solvent reduction silicon composites), electrolytes (solvent decomposition), auxiliary materials (binder/separator degradation), while uniquely establishing their synergistic impacts battery stability. Distinct from prior modular analyses, we emphasize that: (1) emerging systems exhibit fundamentally different thermodynamics compared to conventional materials, exemplified by sulfide solid releasing H2S/SO2 via unique anionic redox pathways; (2) crosstalk between components creates ... Read More

8. Advances in Early Warning of Thermal Runaway in Lithium‐Ion Battery Energy Storage Systems

duzhao han, juan wang, chengxian yin - Wiley, 2025

Abstract Thermal runaway is a critical safety concern in lithium‐ion battery energy storage systems. This review comprehensively analyzes state‐of‐the‐art sensing technologies and strategies for early detection warning of thermal events. The primary inducing factors, evolution mechanism, characteristic reactions at various stages are discussed. Detectable signals during runaway, including temperature, gas emissions, pressure, strain, acoustic signals, examined, along with advancements corresponding technologies. importance sensor implantation, collaboration, communication within cells highlighted, as well the development intelligent algorithms models. Miniaturized, integrated, arrayed sensors identified an inevitable trend advancing monitoring Intrinsically safe design future systems, considering distinct characteristics emerging technologies, crucial enhancing reliability. Future research shall focus on developing advanced real‐time, situ monitoring, establishing new paradigm diagnosis using algorithms, integrating models these accurate state estimation warnings. provides ... Read More

9. Detection toward early-stage thermal runaway gases of Li-ion battery by semiconductor sensor

zixuan teng, cheng lv - Frontiers Media, 2025

While achieving remarkable commercial success, lithium-ion battery (LIBs) carry substantial safety risks associated with potential thermal runaway during widespread applications. When operated under complex working conditions, particularly in high-temperature and high-pressure environments, the internal galvanic reactions within these batteries may escalate uncontrollably. During early stages of LIBs runaway, amounts characteristic gases such as H 2 , CO, CO are released. Safety assess ent current status can be achieved through detecting indicative gas concentrations, thereby enabling efficient safe utilization LIBs. This study provides a mini review research on semiconductor sensors for two key dimensions. Firstly, mechanisms governing entire process elucidated, explicit analysis generation patterns detectable speciation. Subsequently, categorically examines progress targeting four critical categories: carbon oxides, hydrogen, hydrocarbons, volatile electrolytes. work establishes theoretical framework technical reference researchers related fields to advance sensor development, whil... Read More

10. Gas Detection System with Sliding Die and Chamber for Identifying Battery Module Cell Case Defects

LG ENERGY SOLUTION LTD, 2025

Gas detection system for accurately and rapidly identifying damaged cells in battery modules to enable sorting during manufacturing. The system uses a sliding die to move the module into a chamber with multiple gas sensors below it. Circulating gas is purged and then detected by the sensors. This allows locating cells with damaged cases that leak gases. The sliding die and chamber movement allows accessing the module bottom where cracks are more likely. The system enables sorting cells with case defects before module assembly completion.

11. Electrochemical Cell with Vitreous Carbon Electrodes and Gas Analysis Capability for High-Temperature Solid-State Battery Testing

COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES, 2025

Electrochemical cell for testing solid-state batteries at high temperatures with simultaneous measurement of generated gases. The cell has two vitreous carbon electrodes in a ceramic or PEEK cell body with inlet/outlet for carrier gas. It allows testing solid-state batteries while capturing and analyzing gases generated during cycling. The cell body prevents adsorption/corrosion of gases by using non-conductive ceramic or PEEK. The electrodes are fixed to protuberances that move together to apply pressure. This allows testing high pressure solid-state batteries while containing gases.

12. Numerical Model of the Heat-Wait and Seek and Heating Ramp Protocol for the Prediction of Thermal Runaway in Lithium-Ion Batteries

antonio gil, javier monsalveserrano, javier marcogimeno, 2025

<div class="section abstract"><div class="htmlview paragraph">Interest in Battery-Driven Electric Vehicles (EVs) has significantly grown recent years due to the decline of traditional Internal Combustion Engines (ICEs). However, malfunctions Lithium-Ion Batteries (LIBs) can lead catastrophic results such as Thermal Runaway (TR), posing serious safety concerns their high energy release and emission flammable gases. Understanding this phenomenon is essential for reducing risks mitigating its effects. In study, a digital twin an Accelerated Rate Calorimeter (ARC) under Heat-Wait-and-Seek (HWS) procedure developed using Computational Fluid Dynamics (CFD) framework. The CFD model simulates heating cell during HWS procedure, pressure build-up within LIB, gas venting phenomena, exothermic processes LIB degradation internal components. validated against experimental NCA 18650 similar conditions, focusing on temperature domain pressure. effectively captures heat released by undergoing TR through convection radiation surrounding air while providing temporal spatial resolution compo... Read More

13. Battery Thermal Runaway Detection System with Multi-Sensor Monitoring and Selective Activation Mechanism

TDK Corporation, 2025

Early detection and response system for battery thermal runaway to mitigate risks and protect against battery fires in electric vehicles. The system uses multiple sensors in the battery packs and modules to monitor properties like strain, hydrogen gas, pressure, temperature, CO/CO2, and current. An algorithm analyzes the sensor data to detect abnormalities indicating potential thermal runaway. If a risk is detected, high-power sensors like gas sensors are selectively activated to confirm. If elevated gas levels are found, remedial actions like battery disabling are taken before thermal runaway occurs. The system provides earlier and more accurate detection compared to conventional methods.

14. Battery Pack Monitoring System with Piezoelectric Sensors for Detecting Thermal Runaway via Dimensional Changes

SAMSUNG SDI CO., LTD., 2025

Battery pack monitoring system for electric vehicles that can detect thermal runaway in individual cells and initiate safety measures when needed. The system uses piezoelectric sensors attached to the battery pack housing to detect dimensional changes due to internal cell pressure increases. Excessive deformation indicates cell degassing and potential runaway. The sensors are located on opposite sides and outside surfaces of the housing to detect pressure-induced expansion. By monitoring housing deformation over time, runaway can be detected before cell rupture. This allows targeted cell shutdowns and cooling to prevent propagation.

US20250096338A1-patent-drawing

15. Battery Gas Atmosphere Thermal Conductivity Sensor for Early Detection of Thermal Runaway Events

Infineon Technologies AG, 2025

Early detection of thermal runaway events in batteries, like those used in electric vehicles, by detecting the initial venting of gases during the runaway process. A sensor measures the thermal conductivity of the gas atmosphere inside the battery. Changes in conductivity due to venting can be detected as an indicator of an impending thermal runaway. An apparatus with interface and processing circuitry receives the conductivity measurement and determines if venting has occurred. This allows early warning of potential thermal runaway events to mitigate safety risks.

16. Acoustic Sensor-Based System for Detecting Thermal Runaway in Battery Cells Through Infrasound Analysis

VOLVO TRUCK CORPORATION, 2025

Early warning system to detect thermal runaway in electric vehicle batteries using acoustic sensors. The system monitors sound waves emitted from battery cells to predict thermal runaway before it escalates. Acoustic sensors detect low frequency infrasound generated by gas bubbles forming during early stages of thermal runaway. An algorithm analyzes the acoustic data to predict thermal runaway. This allows earlier intervention to prevent escalation compared to temperature sensors.

17. Battery Pack Degassing Unit with Gas Sensor and Processor for Thermal Runaway Prediction

MANN+HUMMEL Ventures Pte. Ltd., 2024

Alert system for predicting battery thermal runaway in electric vehicle packs, using a gas sensor in a degassing unit attached to the battery housing. The sensor detects gas properties like CO2 concentration inside the battery. A processor analyzes the sensor data to estimate the probability of future thermal runaway. The degassing unit has a semipermeable membrane allowing gas exchange but preventing liquid/solid leakage. This isolates the battery interior from external conditions.

US2024260210A1-patent-drawing

18. Battery Pack Fire Suppression System with Gas and Infrared Detection Mechanism

Kidde Technologies Inc., 2024

Fire suppression system for battery packs in vehicles that detects and responds to cell failure gases and fire conditions. The system uses detectors inside battery packs to sense leaked gases like hydrogen and carbon monoxide, as well as infrared radiation. When certain concentration thresholds are reached, an alarm is triggered and a fire suppressant is released into the battery pack. This cools the cells and prevents thermal runaway. The system also dispatches an alarm to the vehicle operator.

US2024204271A1-patent-drawing

19. Battery Pack Fire Suppression System with External Gas and Infrared Detection

Kidde Technologies Inc., 2024

Fire suppression system for battery packs to prevent and extinguish fires in electric vehicle batteries. The system uses external gas detectors to monitor battery cell gases like hydrogen and carbon monoxide, as well as infrared radiation. When detectors sense elevated gas levels or infrared, a controller triggers an emergency fire suppression system to release a cooling agent into the battery packs to smother flames. This prevents runaway cell fires from spreading. The external gas detection allows early intervention before internal sensors are affected.

US2024201039A1-patent-drawing

20. Gas Monitoring System with Selective Sensor Activation for Electric Vehicle Batteries

AUDI AG, 2024

Energy-efficient gas monitoring for electric vehicle batteries that reduces power consumption and extends sensor lifetime while still detecting gas leaks. The monitoring system has a gas sensor unit with multiple sensors that can be woken up selectively to measure gas levels. The sensors are in an idle state most of the time to save power. They are woken up based on events like temperature increases or accidents to check for leaks. This allows targeted sensor activation instead of continuous monitoring.

21. Battery Enclosure Monitoring System with Differential Gas Sensing for Thermal Runaway Detection

22. Battery Monitoring System with Dual Gas Sensors for Differential Detection of Thermal Runaway Indicators

23. Method for Detecting Thermal Runaway Gases in Batteries Using Convolutional Neural Network-Based Sensor Data Analysis

24. Sensor-Based System for Detecting and Mitigating Thermal Runaway Precursors in Electric Vehicle Batteries

25. System for Remote Trace Gas Detection in LiFePO4 Batteries via LoRa Wireless Communication

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