Must Understand for Lithium ion Batteries: Full Life Cycle Fire Risk Analysis

Lithium ion batteries play an irreplaceable role in the fields of consumer electronics and new energy vehicles due to their high energy density and long service life. However, at the same time, lithium-ion batteries have a high risk of fire and explosion. According to incomplete statistics, there were 37 fire accidents related to the lithium-ion battery industry in 2016, distributed in various links such as production, transportation, application, and recycling of lithium-ion batteries.

Therefore, the author conducts a preliminary fire risk analysis for each stage of the life cycle of lithium-ion batteries and shares the main content of the lithium battery loss prevention guide VdS3103, jointly released by the German Insurance Association GDV and the German Professional Safety Association VdS.

Risks during the production process

The production of lithium-ion batteries is a chemical and mechanical process. The electrolyte inside the battery is a flammable liquid, and the electrodes are combustible materials. After the battery is made, electrical testing is required. During the formation stage (i.e. initial charging activation), thermal runaway and fire may occur due to internal short circuits, liquid leakage, and overcharging. During the high-temperature aging stage, batteries can withstand various temperatures and pose a fire hazard.

Risks in storage

Both production areas and storage warehouses may have centralized storage of battery semi-finished or finished products. If the shelf spacing is small and the storage density is high, once a fire breaks out, the fire spreads quickly and is prone to explosion. The German Insurance Industry Association GDV and the German Professional Safety Association VdS issued a notice on the safe storage of lithium batteries in May 2016, classifying batteries according to capacity size and providing relevant safety guidelines, proposing requirements for stacking height, area, spacing, and fire protection system settings. This article will discuss the specific content in detail later.

Risks during transportation

Lithium batteries are mostly produced in Asia and the transportation process is complex, with at least one-third being transported by air. Over the past 10 years, the Federal Bureau of the United States (FAA) has recorded a total of 121 incidents involving batteries (including crashes), most of which were caused by lithium batteries. Since April 2016, the International Civil Aviation Organization (ICAO) has banned the transportation of lithium-ion batteries (UN3480) on passenger planes, except for lithium batteries in electronic devices carried by crew members and passengers.

Risks during use

Lithium batteries are safe under normal usage conditions, but there is a risk of fire and explosion if the battery experiences overcharging, short circuit, collision, water ingress, etc. If not effectively controlled, it may even lead to the combustion of the entire electric vehicle, posing a threat to the safety of passengers.

It is also possible for the charging station to catch fire during the charging process. Energy storage batteries are centrally installed and have a large capacity. If a fire occurs, it can cause the equipment to lose power or burn out, making it unable to operate.

Risks during the recycling process

The types of recycled batteries are diverse and their status is unknown. They may be damaged or defective, and are prone to catching fire due to short circuits, leakage, water ingress, and other reasons. It is even more important to take safety measures.

Lithium Battery Loss Prevention Guidelines VdS3103

In May 2016, the German Insurance Association GDV and the German Professional Safety Association VdS collaborated to release the Lithium Battery Loss Prevention Guide VdS3103. This guide mainly provides loss prevention suggestions for the storage and supply of lithium batteries in the production and storage areas of enterprises. The author has translated and summarized the key points of this guide, and now shares them as follows.

In this guide, lithium batteries are divided into lithium-metal batteries (primary batteries/primary batteries) and lithium-ion batteries (secondary batteries) based on their composition, and low capacity, medium capacity, and high capacity batteries based on their capacity and weight.

Taking common lithium-ion batteries as an example, batteries with a capacity of 100Wh or less are considered low capacity, batteries with a capacity of over 100Wh but a weight less than or equal to 12kg are considered medium capacity, and batteries with a capacity of over 100Wh and/or a weight greater than 12kg are considered high capacity.

Fire risk analysis and loss prevention guidelines for lithium-ion batteries throughout their entire lifecycle

General safety rules

The following safety rules should be followed at all times:

Follow the manufacturer's instructions for use and the product technical data sheet

Prevent external short circuits (such as avoiding short circuits in battery terminals)

Prevent internal short circuits (to avoid mechanical damage)

Do not directly expose to high temperatures or radiation from heat sources, such as sunlight.

In areas where automatic fire suppression systems are not installed, maintain a minimum distance of 2.5 meters from other combustible materials.

Immediately remove damaged or defective batteries from production and storage areas, temporarily place them at a safe distance, or store them in separate areas with fire protection systems installed for processing.

Only batteries that have been tested according to the UN38.3 standard can be stored normally (except for product prototypes that have undergone risk assessment).

Specific security rules

Low capacity battery

Just refer to the general safety rules. If the storage quantity in an area is too large (with a volume of 7 cubic meters or more or more than 6 European pallets), refer to medium capacity batteries.

Medium capacity battery

The storage area for medium capacity batteries should be kept at least 5 meters away from other areas, or fire and flame retardant measures should be taken structurally. Avoid mixing and storing with other products that may act as combustion aids. The storage area should be monitored by a fire detection and alarm system, which is connected to a manned monitoring center. If using a fire extinguishing system, consider using the recommended extinguishing agent in the product data sheet. If the storage quantity in an area is too large (occupying an area of 60 square meters or more and/or the storage height exceeds 3 meters), refer to high-capacity batteries.

High capacity batteries

At present, there is no reliable information that can fully protect high-capacity batteries. Therefore, safety measures should be formulated in consultation with insurance companies based on the specific situation of each case.

Possible measures include:

Isolate and limit quantity

Store in a separate fire-resistant and flame-retardant area or maintain a safe distance (at least 5 meters apart)

Automatic fire extinguishing system

Supply in the production area

If batteries need to be stored in the production area, the following conditions should be met:

Minimize storage quantity (only store daily usage)

Prepare sufficient fire-fighting equipment (fire extinguishers, hydrants)
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