Hope to Prevent Fires on Lithium-ion Batteries

When multiple Li-ion cells are chained together -- such as in electric vehicles -- thermal runaway can spread from one unit to the next, resulting in a very large, hard-to-fight fire.

In conventional batteries- a Li-ion cell, the electrolyte liquid that separates these electrodes can evaporate when it overheats, causing a short circuit. In certain cases, short-circuiting can lead to thermal runaway, a process in which a cell heats itself uncontrollably.

ScienceDaily reported on their latest updated science news as referred to the American Chemical Society.

The volume of fire cases on lithium-ion batteries

The U.S. Consumer Product Safety Commission reported that there were more than 25,000 issues involving fires or overheating stemming from lithium-ion batteries in a five-year period.

Facts about  lithium-ion batteries

1. Low maintenance.
2. No memory effect (they don't have to be completely discharged before recharging, as opposed to other batteries).
3. They can handle hundreds of charge/discharge cycles.
4. Generally lighter than other batteries.

What are lithium-ion batteries?

Each of the fires involved lithium batteries that power laptops, cell phones, and e-cigarettes. Battery fires are unlikely and less severe when used properly. 

However, battery punctures, cracks, and overcharging and under-heat conditions present an increased probability and severity.

Pressure-sensitive vent holes: Batteries are pressurized, and so they need an outer wall made of metal, which has a pressure-sensitive vent hole.

Separator serves as a fuse: Most lithium-ion cells use a separator made of a material known as polyolefin, which boasts good chemical stability, excellent mechanical properties, and is affordable.

Positive Temperature Coefficient: Lithium-ion cells, like all chemical cells, undergo self-discharge. Self-discharge means the batteries lose their stored charge without connecting the electrodes or the external circuit. 

You may read the article about:

 Story of Ancient Electricity.

Amazing Electricity Generation Mobile Power Plant

 

Why do they cause fires?

Lithium-ion (Li-ion) batteries are used to power everything from smart watches to electric vehicles, thanks to the large amounts of energy they can store in small spaces. 

When overheated, however, they're prone to catching fire or even exploding. But recent research published in ACS' Nano Letters offers a possible solution with a new technology that can swiftly put the brakes on a Li-ion battery, shutting it down when it gets too hot.

Components of lithium-ion batteries

Reasons for fire in lithium-ion batteries

The main reasons for fire on lithium-ion batteries, but not limited is as- that batteries can present a fire risk when over-charged, short-circuited, submerged in water, or if they are damaged. 

When lithium-ion batteries fail, they can undergo thermal runaway. This involves violent bursting of one or multiple battery cells, hissing and release of toxic, flammable, and explosive gases, and an intense, self-sustaining fire that can be difficult to extinguish.

Lithium-Ion Battery Fire Protection Technologies.

The latest advancements in lithium-ion battery fire protection focus on a multi-layered approach: Prevention (inherent cell safety and thermal management), Early Detection, and Active Suppression/Containment.

Here is a breakdown of the latest technologies:

1. Inherent Fire Prevention and Cell-Level Safety

These innovations are built directly into the battery components to stop thermal runaway before it can begin.

• Solid-State Electrolytes: This is considered one of the most promising safety advancements. By replacing the highly flammable liquid organic electrolyte with a non-flammable solid material (like ceramics or solid polymers), the risk of fire is significantly reduced, and the batteries offer better thermal stability.

• Self-Extinguishing Electrolytes: Researchers are developing and testing liquid electrolytes that integrate flame-inhibiting chemicals, often modified commercial coolants, that act to put out a fire if thermal runaway is initiated.

• Flame-Retardant Polymers in Cathodes: Specialized polymers are being incorporated into the battery's cathode material. When the battery's internal temperature exceeds a critical threshold (e.g., 

  ${100}^{\circ }\text{C}$

  These polymers break down and release fire-inhibiting radicals, which suppress the buildup of flammable gases.

• Thermal Shutdown Separators: These components are designed to melt and close the pores between the anode and cathode when a high temperature is reached, effectively interrupting the ion flow and cutting off the chemical reaction before a fire can fully develop.

2. Advanced Thermal Management Systems (BTMS)

Since high temperatures are the primary trigger for thermal runaway, advanced cooling is a critical line of defense.

• Hybrid Cooling Systems: The latest systems combine the best features of different cooling methods for maximum efficiency and temperature uniformity. Common combinations include:

  • Liquid Cooling + Phase Change Materials (PCM): PCMs absorb excess heat as they change state (melt), providing passive cooling. This is then integrated with active liquid cooling for continuous, high-efficiency heat removal.

  • Thermoelectric Cooling (TEC) Modules: TEC modules are integrated with PCMs and liquid reservoirs to actively cool the circulating water, enhancing the heat dissipation cycle.

• Direct Liquid Cooling (Immersion Cooling): This method involves submerging the battery cells directly into a non-conductive, low-boiling-point dielectric fluid. This significantly increases the heat transfer coefficient, providing superior cooling performance, and is a potential solution for managing the extreme heat generated during fast charging.

• AI-Based Control Systems: Sophisticated Battery Management Systems (BMS) now use Artificial Intelligence (AI) to monitor battery health, temperature, and voltage in real-time, allowing for the prediction of overheating and the initiation of optimized cooling or heating processes before a dangerous condition is reached.

3. Early Warning and Active Fire Suppression

When prevention fails, the focus shifts to immediate detection and firefighting, especially to stop the fire from spreading (thermal runaway propagation).

• High-Pressure Water Mist Systems: These are one of the most promising active fire suppression techniques. They use a fine mist of water to rapidly cool the batteries, which is the most crucial step in stopping thermal runaway from spreading to adjacent cells.

• Condensed Aerosol Fire Suppression: These systems use a solid chemical agent that, upon activation, generates a large number of inert gases (

  ${\text{N}}_2$

   and 

  ${\text{CO}}_2$

  ) and metal salt particles. This aerosol works by both cooling the flame and chemically disrupting the combustion chain reaction, making it effective for suppressing fire in the early stages.

• Oxygen Reduction Systems: For static energy storage or storage facilities, active fire prevention can be achieved by continuously maintaining an atmosphere with a reduced oxygen level (e.g., 

  $15\mathrm{\%}$

   or less) in the protected area. This is often paired with an early fire detection system for a comprehensive approach.

• Advanced Gas Detection: Since a failing Li-ion battery will vent flammable and toxic gases before flames appear, the latest systems use sensitive gas detectors (e.g., 

  $\text{CO},{\text{H}}_2$

  ) as a much faster way to detect a pre-fire condition than traditional smoke or heat detectors.