In this article, Finch Consulting’s Michael Campbell and Tristan Pulford discuss safety concerns of lithium-ion batteries in industry, and detail control measures you can follow to manage Li-ion battery hazards.
With the drive to reduce the world’s dependency on fossil fuels battery technology has come in to renewed focus as a way of storing and transport energy.
From powering vehicles to providing energy storage solutions, the use of large lithium-based batteries is increasing in a wide range of industries and applications. Battery systems can introduce new, significant hazards into the workplace that must be controlled correctly.
Due to the increased interest and developing technology of batteries, any type of incident will draw interest in the media. From burning (and in some cases reigniting) car fires to the injuries incurred by vape devices exploding, a quick search of the internet can provide evidence of the dangers of lithium-ion batteries. Despite this, batteries are safe to use providing suitable control and mitigation methods are put in place throughout the product life cycle.
Safety Concerns of Lithium-ion Battery Failures
Lithium-ion battery failures can occur due to imperfections in the construction of the cell or through abuse. Abuse of cells, packs or modules can be caused by impact, such as dropping or collisions in transit, piercing from tooling, shorting, over charging and being exposed to higher or lower temperatures than those that the battery is designed for. Once a battery has been damaged it may take some time to develop symptoms such as swelling or heating.
Lithium-ion batteries can react in a variety of different ways depending on the type of fault, the area that is damaged, state of charge and chemistry of the affected battery. It has been difficult to consistently predict the same failure behaviour of a cell, even in laboratory conditions.
• Damaged cells may vent / smoke without ignition.
• Fires may occur when the electrolyte ignites.
• A jet of flame and burning material being ejected from a single point can create a flare.
• The battery may burn or create a fireball, depending on the failure mode.
• The battery may also explode.
Lithium-ion cells can transition between reactions. Venting cells can catch fire, then explode, they may also vent then explode without catching fire.
Burning lithium-ion cells can and do create carbon dioxide and water. This smoke is generally made of hydrogen, carbon monoxide, carbon dioxide and a range of hydrocarbons although the exact composition of the smoke is dependent on the chemistry used. Fluorine can also be released from the battery, which can combine with hydrogen to produce hydrogen fluoride, this in turn will react with water, including water vapor or with mucus membranes in the human body to create hydrofluoric acid.
Once a battery cell has failed the heat generated can cause other cells in close proximity (stored together or together in modules and packs) to fail, resulting in a chain reaction (also known as the snowball effect or runaway).
Control Measures to Control Lithium-ion Battery Hazards
Storage and Movement
Correct storage and protection of batteries is vital to reduce the risk of damage. If forklift trucks are used for transportation, controls must be in place to reduce the risk of piercing or damaging cells. If stored at height, protection should be given to prevent batteries from falling. Batteries should be segregated as much as possible to prevent a failure propagating through storage or work areas.
Remove the Risk of Damaging Batteries When Possible
For maintenance tasks, alignment operations and training “dummy” cells, modules and packs should be used where possible. Dummy cells, modules and packs are constructed (and if needed weighted) to resemble components, however they are inert, meaning that if they are damaged that they will not react in the same way a “live” component with electrolyte would.
Detection, Monitoring and Reacting to Failing Batteries
Monitoring systems should be used where a risk assessment has identified the need, to monitor the temperature of batteries as failing devices tend to increase in heat before more severe reactions occur. If there is a possibility of vented gasses, then monitors should be used so that employees can be evacuated. Evacuation routes should be provided to quarantine areas if monitoring systems detect a damaged device.
Emergency incident plans should be put in to place so that in the case of a battery venting or a fire, there is a clear action plan is in place. This should be practised where possible. This may involve isolating the damaged product safely or leaving the product in place. If the product is left in place, then the risk of fire spreading through storage or equipment should be considered.
When moving a potentially damaged battery, then appropriate personal protective equipment such as goggles, aprons and RPE should be provided for those exposed. If the battery system is large and devices such as forklift trucks are required, the safety of operating these devices whilst using protective equipment should be considered. In the event a battery system does vent hazardous fumes, a system of ventilating the area should be considered.
Because of the possible time delay in detecting a damaged battery, a quarantine system should be provided to enable suspect cells, modules, or entire packs to be isolated safely away from people or flammable material including other batteries.
Only approved charging systems should be used to prevent overcharging. Many of the incidents involving vape devices are caused by poor quality chargers. Any charging device used must be evaluated to ensure it is fit for purpose.
Protection from Shorts Circuits and Electric Shock
Protection should be provided to prevent short circuits such as guarding connections, insulated tools and removal of all non-essential conductive materials such as coins and jewellery.
Isolation procedures should be provided to disconnect the battery system in line with procedures such as lock out tag out (LOTO) however, maintaining or constructing battery modules and packs can pose risks of electric shock that cannot be eliminated.
If possible, the voltage of the battery system should be reduced to a minimum before any intrusive work is undertaken. Battery modules and packs should be designed so that when being manufactured or maintenance is being undertaken covers provide protection against short circuits or accidental contact. Processes should be designed so that covers are only removed when required and in a sequence that prevents the possibility of shorts.
Using PPE as a Control Measure
As with all risk reduction methods, PPE should only be considered as a safeguard if hazards cannot be adequately controlled by other means. Some possible PPE that may be used include insulating gloves, many of which require over gloves to prevent piercing of the insulating glove. Insulating gloves can cause hands to sweat, an inner lining glove may be required to absorb sweat however because the insulating glove does not “breathe” there is an increased risk of skin conditions such as dermatitis. Face shields and protective clothing may also be considered to protect against flash and burns. If used for prolonged periods, this PPE can cause fatigue and overheating.
Controls of Major Accident Hazards (COMAH), Control of Substances Hazardous to Health (COSHH) and Registration, Evaluation, Authorisation & restriction of Chemicals (REACH)
Depending on the chemistry of the battery there are various other regulatory considerations to be undertaken which although appear to be simple, in practise can be very complex. As previously mentioned within this article, the COSHH regulations will cover the hazards associated with the normal use and maintenance of the batteries and should provide control measures such as storage, procedures, PPE and information.
Depending on the selection, the amount stored and the other substances on site, the storage and use of batteries may cause a site to fall under the COMAH regulations. The COMAH regulations are designed to control major hazards which have the potential to “snowball” and limit the damage to people, plant and the environment. While on the face of it, a lithium-based battery would fall under COMAH if 100 tonnes or more was stored due to the fact flammable gases may be released, it is not as simple as that. This is because not all of a batteries mass is lithium, but also because the consideration must be given to charging. As mentioned previously, when charging hydrogen is generated, and if the concurrent charging produces enough hydrogen, a cumulative approach must be undertaken.
Similarly, REACH (UK REACH from 1 January 2021) must be considered (until Brexit happens) depending on the limits. The key with all these regulations is that because the process involves chemical/electrochemical reactions, the materials in the charged and uncharged states should be considered.
If you are using batteries on-site, then you need to be aware of what to do when you no longer need them. There are special requirements that need to be followed for waste batteries and they should not be mixed with other waste. While awaiting collection, batteries should be stored on an impermeable surface and with suitable waterproof coverings.
When batteries become waste, they are covered by two pieces of legislation:
• The Waste Batteries and Accumulators Regulations 2009, which applies to portable batteries, industrial and automotive batteries, and button cell batteries.
• The Hazardous Waste (England and Wales) Regulations 2005, because they contain a measurable amount of different heavy metals.
The ‘producer of batteries and accumulators’ is the first person in the UK selling chain responsible for the supply and sale of batteries. They are required to take responsibility for separately collecting and recycling batteries and accumulators once they become waste. Therefore, the producer or retailer must offer to take batteries back free of charge.
If the batteries are part of waste electrical or electronic equipment, then they need to be recorded separately as part of the Waste Electrical and Electronic Equipment (WEEE) Regulations 2013 (as amended). Even if the Electrical and Electronic Equipment (EEE) does not fall under the WEEE Regulations, then the batteries still need to be returned to the producer.
If you wish to treat and recycle portable batteries or industrial and automotive batteries on site, then you must be an Approved Battery Treatment Operator (ABTO).
As part of your waste Duty of Care, you must ensure that the battery collector is taking the batteries to a site with an environmental permit for treating and recycling waste batteries. It is illegal to send waste industrial or vehicle and other automotive batteries for incineration or to landfill.