Love them or hate them, batteries are an integral part of modern living. However, recent incidents have raised their profile from help to hindrance – this article will discuss the considerations that should be made when responding to an incident involving different battery types.
What is a battery?
In simple terms, an electric battery comprises a number of cells in which chemical energy is converted into electrical energy. Even the humble potato can be used as the electrolyte in a battery, and many of you or your children will have conducted this experiment at school. Each cell comprises three separate components: an anode, a cathode and an electrolyte – each component could be a different hazardous material. When the external circuit is complete (by connecting an electrical load) electrons flow from the anode to the cathode.
Batteries are part of modern life – be it in mobile devices, cars or for back-up in the event of power cuts. As hazardous materials are used in battery construction, many incidents involving batteries become ‘hazmat’ (hazardous material) situations. NCEC have provided advice across a number of high-profile incidents involving mobile phones, hover boards and even brand-new aircraft in recent years.
What is the hazard?
The rise in electric vehicles, portable electronic devices and energy storage solutions will bring the emergency services more and more into contact with these hazmat situations. Each type of battery is built in a different way, and incidents involving these need to be handled differently:
Lead acid
- Lead-acid batteries are normally used in cars, but can be used in other energy storage solutions.
- When fully charged, a lead-acid battery contains an electrolyte of sulfuric acid with an anode of lead and a cathode of lead dioxide.
- As the battery becomes discharged the sulfuric acid electrolyte is diluted, and the two plates are converted to lead sulphate.
- As the electrolyte discharges, it is also more prone to freezing.
- If excessive charging occurs, more hydrogen and oxygen can be produced, which increases the risk of an internal explosion. Normally the gas will be vented, but if the battery malfunctions, or overheats, gas may build up within the unit.
- Lead-acid batteries can give off hydrogen and hydrogen sulphide, but in small quantities so will only be a risk in a confined space with a ready ignition source.
- If any of these situations occur then NCEC’s standard advice would be to disconnect the battery and ventilate, and seek additional assistance if the situation escalates.
Lithium (or lithium-metal)
- Lithium-metal batteries are used in watches, cameras and other long-life applications such as pacemakers.
- The lithium metal is the anode in the battery and the electrons flow through an electrolyte made up of a lithium salt in an organic solvent to a cathode commonly made of manganese dioxide.
- If short circuited, they discharge very rapidly resulting in overheating, the case rupturing or an explosion.
- Most consumer batteries will incorporate overcurrent or thermal protection to prevent explosion.
- These batteries are also convenient sources of lithium metal for illegal drug laboratories.
- In the event of a fire, and since the batteries contain lithium metal and a flammable electrolyte, a dry agent is the advised extinguishing media for lithium metal batteries (UN3090 and UN3091). If in doubt, NCEC’s advice would be to consider a controlled burn.
Lithium-ion
- Lithium-ion batteries are used in mobiles, laptops and electric vehicles.
- The anode in a lithium-ion battery is made of carbon and the cathode is made of a metal oxide. The electrolyte is made from a lithium salt in an organic solvent.
- The batteries produce heat in the anode and oxygen at the cathode.
- If overheated or overcharged, the batteries may suffer thermal runaway and cell rupture, which can lead to combustion in extreme cases.
- A number of safety features are added to the batteries to prevent overheating or pressurisation, but manufacturing faults have resulted in mass recalls.
- Rechargeable lithium-ion batteries contain no metallic lithium but a flammable electrolyte. Therefore, water is the best extinguishing media for lithium-ion batteries (UN3480 and UN3481). If in doubt, NCEC’s advice would be to consider a controlled burn.
What about large-scale incidents?
NCEC have been involved in supporting the response to a number of large-scale incidents over the last year. For example, a wind farm was being constructed which comprised 12 wind turbines. They decided to use a battery storage solution on site to ‘smooth’ the energy supply. Manufacturing defects in the capacitors resulted in two fires in consecutive months. Following advice, these fires had been allowed to burn out with minimal damage. However, a longer-term solution was required, and the company decided that, with this emerging technology, they should have effective fire protection in place. NCEC would recommend that a stockpile of dry agent is made available at any location with a large number of battery cells.
Another fire involved 12,000 lead-acid batteries. The dry agent and bulk carbon dioxide sourced by the fire and rescue service were ineffective. Therefore, they fought the fire defensively with water to stop it from spreading to adjacent buildings and infrastructure. The fire caused £12 million of damage to the facility. On a large scale, NCEC would recommend that the only effective option for lead-acid battery fires would be defensive water application. However, if the risk is too great, a controlled burn can be considered. As always, context and circumstances at the scene need to be considered when deciding the response, and expert chemical advice can help those at the scene make the most appropriate decisions.
What is the future?
The world of batteries is constantly striving for better solutions to satisfy the demand for consumer electronics and future sustainable transport. This research is providing innovative solutions, but this can result in a hazmat situation for emergency services to deal with during previously standard incidents. Being prepared to deal with these types of incidents is key, and access to chemical advice to help formulate a response strategy is critical when dealing with new technology.
The NCEC provide hazardous material incident support and chemical advice for emergency services globally, as well as chemical safety training and preparedness on a variety of topics including batteries.
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