Causes of Fire in Battery, Thermal Runway and Its Prevention

Major Causes of Fires in Battery 

  • The battery is a critical part of electric vehicles. Fires in electrical vehicles have been observed in many places due to several issues. It is important to design a safer battery for its applications.
  • Fires in batteries, especially lithium-ion batteries commonly used in electronic devices, electric vehicles, and renewable energy storage systems, can be caused by several factors.
  • Understanding these causes is essential for implementing effective fire prevention strategies.
  • Here are some common causes of battery fires and preventive measures:

Thermal Runaway

  • Cause:
    • Thermal runaway occurs when a single cell in the battery pack overheats due to internal short circuits, external damage, or manufacturing defects.
    • This can lead to a chain reaction, causing nearby cells to also overheat and potentially catch fire.
  • Prevention:
    • Control the temperature within 15 to 40°C
    • Keep battery in ventilation areas
    • Implement thorough quality control during battery manufacturing, use advanced Battery Thermal Management Systems (BMS) to monitor and manage individual cell conditions, and ensure proper thermal management with cooling and venting systems.

 

Overcharging and Over discharging

  • Cause:
    • Charging a battery beyond its designed voltage limits (overcharging) or discharging it too deeply (over-discharging) can lead to internal damage and subsequent thermal runaway.
  • Prevention:
    • Employ accurate charging and discharging algorithms through the BMS, which prevent the battery from operating outside safe voltage ranges.
    • This includes using charge limiters and discharge cutoffs.

Effect_temperature on Battery life

Manufacturing Defects

  • Cause: Poor manufacturing processes can introduce defects like metal particles, insulation breaches, or internal shorts, which increase the risk of short circuits and overheating.
  • Prevention: Implement stringent quality control measures during battery production, such as X-ray and other inspection methods to detect defects before they cause problems.

Mechanical Damage

  • Cause:
    • Physical impacts, punctures, or crushing can damage the battery pack’s cells and separators, potentially leading to internal short circuits and thermal runaway.
  • Prevention:
    • Design battery packs with appropriate structural protection, employ shock-absorbing materials, a
    • Ensure the battery’s placement within the vehicle or device minimizes exposure to potential impacts.

 High Temperatures of battery

  • Cause:
    • Exposing lithium-ion batteries to high temperatures, either during operation or storage, can accelerate chemical reactions and increase the risk of thermal runaway.
  • Prevention:
    • Incorporate effective thermal management systems to maintain the battery within its safe temperature range.
    • Store batteries in cool environments and avoid leaving them in direct sunlight.

External Heat Sources

  • Cause:
    • External heat sources, such as fires in the surrounding environment,
    • It can cause batteries to catch fire.
  • Prevention:
    • Design battery packs and enclosures that provide fire-resistant barriers, heat shields, and other protective measures to prevent external heat from affecting the battery cells.

Use of Counterfeit Batteries

  • Cause: Poor-quality counterfeit batteries often lack proper safety features and can be more prone to overheating and failure.
  • Prevention: Purchase batteries from reputable sources, avoid counterfeit products, and follow manufacturer recommendations for replacement parts.

Manufacturing Contaminants

  • Cause: Contaminants introduced during the manufacturing process can lead to internal short circuits or other defects.
  • Prevention: Ensure strict cleanliness and quality control measures during battery production to minimize the risk of contamination.

 Inadequate Venting:

  • Cause: Accumulation of gases produced during normal battery operation can cause pressure buildup inside the battery, leading to rupture or explosion.
  • Prevention: Design battery packs with proper venting mechanisms that allow the safe release of gases in case of pressure buildup.

Venting of battery to prevent fire

What is the Thermal Runway in Battery?

  • Thermal runaway in batteries refers to a self-perpetuating, uncontrolled increase in temperature within the battery cell or battery pack.
  • It occurs when the heat generated within the battery due to chemical reactions exceeds the ability of the cooling or dissipation systems to remove that heat.
  • This can lead to a chain reaction of increasing temperatures, which can be dangerous and result in fires or explosions, especially in high-energy-density batteries like lithium-ion batteries.

  • In the context of lithium-ion batteries, thermal runaway can be triggered by various factors, such as manufacturing defects, physical damage, overcharging, or exposure to high temperatures. Once initiated, the high temperature can cause the release of flammable materials within the battery, leading to further heating and potentially catastrophic outcomes.

  • Thermal runaway is a critical concern, particularly in applications like electric vehicles and energy storage, where large numbers of batteries are packed closely together.
  • Proper design, manufacturing, and safety measures are crucial to minimize the risk of thermal runaway and ensure the safe operation of battery systems.

Causes of Thermal Runway

Here’s a step-by-step explanation of thermal runaway in batteries:

  1. Initial Trigger: Thermal runaway often starts with an internal short circuit or an external factor that causes the battery cell to heat up. This could be due to manufacturing defects, physical damage, overcharging, over-discharging, or exposure to high temperatures.
  2. Increased Heat Generation: As the temperature of the cell increases, it accelerates the chemical reactions inside the battery. This produces more heat as the reactions become more energetic.
  3. Electrolyte Breakdown: The high temperature can cause the breakdown of the electrolyte—the liquid or gel-like substance that facilitates the movement of ions between the battery’s positive and negative electrodes.
  4. Gas Generation: The breakdown of the electrolyte can lead to the generation of gases, including oxygen and flammable hydrocarbons.
  5. Pressure Buildup: The accumulation of gases causes pressure to build up within the cell. This pressure can lead to swelling, deformation, or even rupture of the cell casing.
  6. Positive Feedback Loop: The increased temperature and pressure can further accelerate the chemical reactions, creating a positive feedback loop. This means that as the temperature rises, the chemical reactions become even more energetic, leading to a rapid escalation of heat and pressure.
  7. Fire or Explosion: If the conditions continue to worsen, the cell may reach a point where it experiences a catastrophic failure. This can result in the release of hot gases, flames, and potentially an explosion.
  • Efforts to prevent thermal runaway involve designing battery systems with safety mechanisms to detect and mitigate temperature and pressure increases.
  • Advanced Battery Management Systems (BMS) are used to monitor individual cell conditions, manage temperature, and prevent overcharging or over-discharging.
  • Additionally, thermal management systems, like cooling and venting, are employed to regulate the battery’s temperature and prevent the buildup of excessive heat.

Scope of CFD Modeling in Fire Predictions in Battery

  • Computational Fluid Dynamics (CFD) modeling can be a valuable tool for analyzing and predicting fires in battery systems, including lithium-ion batteries commonly used in electric vehicles, consumer electronics, and energy storage applications.
  • CFD simulations allow researchers and engineers to study the behavior of heat, gases, and airflow within the battery system during a fire event. Here’s an overview of how CFD modeling is applied to fires in battery systems:

Geometry and Mesh Generation:

  • Create a detailed 3D digital model of the battery system, including the battery cells, casing, cooling systems, vents, and any surrounding components.
  • Divide the geometry into a mesh of small cells, ensuring the mesh resolution is sufficient to capture the relevant physical phenomena.

Temperature _Contours_battery_during_Discharge_CFD_Results

Material Properties:

  • Define the material properties of the battery components, including thermal conductivity, specific heat, density, and other relevant properties. You can define temperature-dependent thermal properties in CFD solvers
  • Define the chemical species of materials

Boundary Conditions:

  • Specify the initial conditions, including temperature distribution, gas concentrations, and any existing flow patterns.
  • Define external factors such as the ambient temperature, initial pressure, and any sources of heat or fire ignition.

Heat Transfer and Combustion Modeling:

  • Simulate heat transfer mechanisms, including conduction, convection, and radiation, within the battery system.
  • Implement combustion models that consider the chemical reactions and heat release associated with the battery materials burning or undergoing thermal decomposition.
  • Implement combustion models to simulate the chemical reactions and heat release rates associated with battery fires.

Fluid Dynamics and Flow Analysis:

  • Simulate the flow of gases (such as smoke and hot air) within the battery system due to natural convection and forced airflow (if applicable).
  • Study how gases and heat are transported through the battery pack, cooling systems, and any ventilation or exhaust paths.

Species Transport and Smoke Analysis:

  • Model the transport of different gases and species released during a fire event.
  • Analyze the spread of smoke and toxic gases, which can have implications for both safety and emergency response strategies.

Validation and Sensitivity Analysis

  • Validate the CFD model by comparing simulation results with experimental data or real-world scenarios to ensure accuracy.
  • Conduct sensitivity analyzes to understand the impact of various parameters on fire behavior, such as initial conditions, material properties, and boundary conditions.

Emergency Response Planning:

  • CFD simulations can provide insights into the behavior of fires, such as flame propagation, smoke distribution, and gas concentration levels.
  • This information can aid emergency responders in developing effective strategies to control and mitigate fires in battery systems.

Summary

  • Preventing battery fires involves a combination of proper design, manufacturing quality, robust safety features, and user education. Regular monitoring, maintenance, and adherence to safety guidelines are crucial for ensuring the safe operation of batteries across various applications.
  • Preventing thermal runaway is essential for the safety of battery-powered devices, electric vehicles, and stationary energy storage systems.
  • Through careful design, rigorous testing, and proper maintenance, the risks associated with thermal runaway can be significantly reduced
  • CFD modeling of fires in battery systems is a complex and specialized field that requires expertise in fluid dynamics, heat transfer, combustion, and numerical simulation techniques.
  • CFD modeling can provide valuable insights into fire behavior, thermal management strategies, and safety improvements for battery-powered devices and vehicles.

Leave a Comment