Lithium batteries, known for their high energy density, are prone to thermal runaway, which can be triggered by three types of abuse: mechanical, electrical, and heat. Mechanical abuse involves external forces such as collisions, extrusions, and punctures, compromising the battery’s structure. Electrical abuse includes both internal and external short circuits, overcharging, and discharging, which can lead to internal damage. Thermal abuse results from external heating of the battery, worsening the situation.

The process of thermal runaway begins with mechanical abuse, leading to internal diaphragm breakage and resulting in an electrical short circuit. Subsequently, electrical abuse triggers thermal abuse, as short circuits generate heat, initiating chemical reactions at high temperatures. This further exacerbates thermal abuse, creating a self-sustaining cycle. When the accumulated heat reaches a critical level, thermal runaway occurs, potentially leading to an explosive event.

This article provides a detailed analysis of the chemical reactions inside lithium batteries, focusing on positive, negative, and electrolyte perspectives. These reactions are carefully classified based on various trigger temperatures. The study introduces an innovative approach, suggesting the use of gases produced during lithium battery heating for early warning diagnosis. By distinguishing abnormal gases from normal ones, these gases serve as crucial indicators for potential thermal runaway.

Research on Internal Chemical Reactions of Lithium Batteries

Theoretical Basis

It is essential to comprehend the structure of lithium batteries. These batteries consist of a positive electrode, a negative electrode, and an electrolyte, operating based on positive electrode discharge and charging reactions. The electrolyte contains two or more solvents and one or more lithium salts, ensuring the battery’s peak performance.

Research on Chemical Reactions

Positive Electrode and Electrolyte Reaction:

The thermal breakdown of the positive electrode releases oxygen, a key factor in triggering thermal runaway. This oxygen, along with other reactions, sets off a chain effect that leads to thermal runaway.

Negative Electrode and Electrolyte Reaction:

The negative electrode’s surface area is crucial in its reaction. When the Solid Electrolyte Interface (SEI) decomposes, it exposes the negative electrode to the electrolyte, impacting subsequent reactions.

Electrolyte Reaction:

The breakdown of solute LiPF6 and its interactions with other components such as DEC and HF influence the overall chemical environment within the battery.

Trigger Sequence of Chemical Reactions

The chemical reactions inside lithium batteries follow a sequence of trigger temperatures. Each reaction stage, from LiPF6 decomposition at 60-70°C to diaphragm dissolution at 130-190°C, is crucial for understanding the thermal runaway process.

Early Warning and Diagnostic Strategy

Early warning diagnosis relies on distinguishing gases produced under normal and abnormal conditions. The unique content, change rate, and type of these gases offer valuable clues for early warning systems. Abnormal gases such as CO2 and PF5 differ significantly from normal gases like CO and C2H4, allowing for targeted sensor implementation and accurate diagnosis thresholds.

Leave a Reply

Your email address will not be published. Required fields are marked *

Explore More

Maximizing Battery Performance: The Importance of Equalization

March 24, 2024 0 Comments 0 tags

Battery packs, especially those used in electric vehicles and energy storage systems, often consist of multiple battery units connected in series. While this configuration offers higher voltage, it can lead

Choosing the Right Battery-Making Equipment for Your Production Needs: Factors to Consider

battery-making equipment
June 3, 2024 0 Comments 5 tags

Are you someone looking for lithium-ion battery-making equipment for a new plant? Do you have things in your mind cluttered with ideas that lack execution? The problem starts when someone

Lithium-ion Battery Fire Safety: Early Detection and Suppression Technologies

January 8, 2024 0 Comments 0 tags

Lithium-ion batteries are the workhorses of the modern world, powering everything from our smartphones to electric vehicles. However, these powerful energy storage devices also come with a potential fire risk.