Risk Analysis and Protection of Lithium Battery Total Life Cycle Fire

Lithium-ion batteries have an irreplaceable role in consumer electronics and new energy vehicles because of their high energy density and long service life. But at the same time, lithium-ion battery fire risk is high, prone to fire explosion. According to incomplete statistics, there were 37 fire accidents related to the lithium battery industry in 2016, which were distributed in the production, transportation, application, and recycling of lithium ion batteries.

Therefore, the author conducts a preliminary fire risk analysis for each phase of lithium-ion battery life cycle, and shares the main contents of VdS3103, a guide for the protection of lithium-ion batteries issued by the German Insurance Association GDV and the German Professional Safety Association VdS.

Risks in 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 electrode is a flammable material. After the battery is made, an electrical test is required. During the chemical phase( the first charge is activated), it is possible that the fire may be out of control due to internal short circuits, leakage of fluid, and overcharging. The high temperature aging phase of the battery to withstand a variety of temperatures also brings fire risk.

Risk Analysis and Protection Guidelines for Lithium Battery Total Life Cycle Fire

Risks in storage

It is possible to centralize the storage of semi-finished or finished batteries in production areas and storage warehouses. For example, the shelf spacing is small, the storage density is high, and once the fire starts, the fire spreads quickly and is prone to explosion. The German Insurance Industry Association GDV and the German Professional Safety Association VdS issued an announcement on the safe storage of lithium batteries in May 2016. The batteries were classified according to the size of the capacity, and relevant safety guidelines were given. The height, area, spacing, and fire system setting were proposed. Requirements. The details are discussed in detail later in this article.

Risks in transport

Lithium-ion batteries are mostly produced in Asia and are transported through complex processes, with at least one third transported by air. In the past 10 years, FAA of the United States Federal Aviation Administration has recorded a total of 121 battery-related accidents(including crashes), most of which were caused by lithium batteries. Since April 2016, ICAO has banned passenger aircraft from transporting lithium-ion batteries(UN 3480), except for lithium batteries in electronic equipment carried by crew and passengers.

Risks in use

Lithium batteries are safe under normal operating conditions, but if the battery is overcharged, short-circuited, collided, and flooded, there is a risk of fire explosion. If it can not be effectively controlled, it will even lead to the burning of electric vehicles, which will threaten the safety of passengers.

It is also possible for the charging pile to catch fire during charging. Energy storage batteries are centrally set and have a large capacity. If a fire breaks out, the equipment will be cut off or burned and can not be operated.

Risks in the recovery process

The types of batteries recovered are diverse and the status is unknown. They may be damaged or defective. They are easily caught in flames due to short circuits, leaks, and water intake. More attention should be paid to safety measures.

Lithium Battery Protection Guide VdS3103

In May 2016, the German Insurance Association GDV and the German Professional Safety Association VdS jointly released the guidelines for the protection of lithium batteries against damage VdS3103. The guide provides recommendations 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 the guide, which are now shared as follows.

In the guide, lithium batteries are divided into lithium metal batteries(primary battery/primary batteries) and lithium ion batteries(secondary batteries) by component, and are divided into low-capacity, medium-capacity and high-capacity batteries by capacity and weight.

Take a common lithium ion battery as an example. Batteries with a capacity of 100Wh or less are low capacity, batteries with a weight of 100 Wh or more but a weight of less than or equal to 12 kg are medium capacity, and batteries with a weight of more than 100Wh and/or a weight of more than 12 kg are high capacity.

General security rules

The following safety rules shall be observed at all times:

Follow the instructions provided by the manufacturer and the technical data sheet of the product

Prevent external short circuit(e.g. avoid battery terminal short circuit)

Prevent internal short circuit(avoid mechanical damage)

Do not be directly exposed to high temperatures or heat sources, such as sunlight.

Maintain a minimum distance of 2.5 m from other combustible materials in areas where no automatic fire suppression system is installed.

Remove damaged or defective batteries immediately from production and storage areas, temporarily place them outside a safe distance, or store them in a separate area equipped with a fire protection system for disposal.

Only batteries tested according to UN standard 38.3 can be stored normally(except for prototype products after risk assessment).

Specific security rules

Low capacity batteries

Refer to general security rules. If the amount of storage in an area is too large(more than 7 cubic meters in volume or more than 6 European pallets), refer to medium-capacity batteries.

Medium capacity batteries

The medium-capacity battery storage area needs to be kept at least 5 meters apart from other areas, or fire retardant measures are adopted in the structure. Avoid mixing storage with other products that act as accelerators. The storage area should be monitored by a fire detection alarm system, which is connected to a manned monitoring center. If fire extinguishing system is used, consider using the fire extinguishing agent recommended in the Product Data Sheet. If the amount of storage in an area is too large(covers an area of more than 60 square meters and/or has a storage height of more than 3 meters), refer to high-capacity batteries.

High capacity batteries

At present, there is no reliable information that can fully protect high-capacity batteries. Security measures should therefore be developed in consultation with insurance companies, depending on the circumstances of each case.

Possible measures include:

Isolation and limitation of quantity

Store in a separate fire retardant area or maintain a safe distance(above 5 M spacing)

Automatic fire extinguishing system

Supply in production areas

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

Minimize the amount of storage(only the daily usage required)

Prepare adequate fire extinguishing equipment(fire extinguishers, hydrants)

The page contains the contents of the machine translation.