Dangers when handling lithium-ion batteries

Lithium-ion batteries are a comparatively recent technology. But since its market launch in the early 1990s, they have left a lasting mark on the energy storage market and gradually displaced old technologies. Today, it is impossible to imagine our everyday life without lithium batteries - and for a good reason: they can be tiny and, at the same time, very efficient and are, therefore, of interest for a wide range of applications. Not only do smartphones and tablets draw their energy from lithium batteries, but they also play an essential role in electromobility. Lithium energy storage devices are ideal because of their high energy density, low weight, and fast charging.

On the other side of the coin, dangerous incidents involving lithium energy storage devices are repeatedly reported. In 2017, a fire in a parking garage made the headlines caused by an e-bike's battery. In 2018, a man from Hamburg died when a battery charger exploded. There is no question: explosions and fires involving lithium-ion batteries can have devastating consequences, causing expensive consequential damage or, in the worst case, costing human lives. It's not just members of the public but also companies facing the urgent problem of ensuring the safest possible handling and storage. The fact remains that §5 ArbSchG obliges employers to identify and assess hazards and to implement suitable protective measures.

By today's manufacturing standards, lithium batteries are considered comparatively safe. As a rule, the manufacturer carries out various safety tests before (series) products are put on the market. For example, the transport of lithium energy storage devices is only permitted if a test certificate by UN 38.3 is available. To obtain this certificate, several tests must be completed to test the batteries under various transport conditions. This includes:

Nevertheless, special care should be taken when handling lithium-ion batteries - because dangerous fires occur repeatedly. If anything happens, the consequences are often disastrous. The risk lies in the construction of the battery itself. Where materials with a high energy density come into contact with the highly flammable electrolyte, these create a hazardous mix. The situation becomes especially dangerous when a lithium battery releases its stored energy uncontrolled. As soon as the heat produced exceeds the melting point of the separator, an uncontrollable chain reaction is started, the dreaded "thermal runaway."

The high levels of heat energy then vaporize the electrolyte fluid, creating additional heat and combustible gases. If the pressure rises above a certain point, the flammable gases are released, forming an ignitable mixture with the air - flames develop outside the battery. Thermal runaway in just one cell is enough to heat the neighbouring cells in a battery block, creating a devastating chain reaction. Once set in motion, it only takes a few minutes until the battery will burn and explode. These lithium-ion battery fires are difficult to control, and the fire spread quickly. The fire brigade can often only protect neighbouring areas.

In typical operation, the use of lithium batteries is considered safe. However, according to VDE, this only applies if everyone handles them correctly. For example, if lithium-ion batteries are handled or stored incorrectly, they can pose a significant safety risk. In addition, factory defects cannot always be ruled out.

Electrical overload

A typical risk in handling lithium batteries is common, namely charging and discharging. An electrical overload can occur here for several reasons, e.g., using an incorrect charger. But fire can also occur as a result of a deep discharge. Lithium-ion batteries can become completely discharged if they are not used for a long time. Incorrect storage conditions - for example, outside the manufacturer's recommended storage temperature - can promote this effect. This leads to the decomposition of the electrolyte liquid and, consequently, to the formation of highly flammable gases. If an attempt is made to recharge the deeply discharged lithium-ion cells, the energy supplied can no longer be converted correctly due to insufficient electrolyte fluid. A short circuit or fire may occur.

Mechanical damage

When handling lithium-ion batteries, there is always a particular risk of damaging them. Collisions with company vehicles, falling onto the hard ground, or crushing due to incorrect storage conditions are just a few examples of mechanical damage. If cells are deformed, this can lead to internal short circuits and a fire in the battery. Also, contamination during the production of the cells themselves cannot be 100% ruled out. In rare cases, particles that enter the cell during production can damage it from the inside over time. Internal short circuits can then also occur.

Thermal overload

External heat or energy sources can heat lithium batteries and thus lead to fire due to thermal overload. Typical sources of danger are, for example, open fire, hot machine parts, or storage in direct sunlight.