Managing the Lithium (Ion) Battery Fire Risk
Lithium-based batteries are inexpensive, lightweight, powerful, and environmentally safer than most alternatives. However, they generate large amounts of energy and the fire and explosion risk associated with them can be high. Storing large amounts of energy, whether it's in large batteries used in energy storage applications, smaller batteries used in electric vehicles, or even smaller batteries used in common electronic equipment, can be inherently dangerous.
Anytime energy is stored in a confined space it tries to escape, sometimes violently. Considerable effort should be made to manage the entire life cycle of these batteries, with special attention paid to safety and fire/explosion issues. Lithium battery risk and safety management remains a young yet important field. It presents challenges to a wide range of industries that manufacture, ship, store, and manipulate these powerful tools. It also presents challenges relative to risk management. How does the risk management industry quantify the threat? How do we protect against the potential dangers? What are the safety considerations? What are the underwriting issues?
Lithium batteries versus lithium ion batteries
For the purpose of ease of understanding, batteries referred to in this article will be called “lithium” batteries, unless specified. The reality is that lithium and lithium ion batteries are different. Lithium batteries, or primary batteries, are single use and incapable of recharge. They contain lithium metal which is highly combustible. The real value in lithium lies in the fact that they deliver extremely high energy densities in small configurations. They are used where recharge isn’t necessary or feasible. Common applications include military use (war fighter applications), medical applications, and certain consumer electronics applications, to name a few.
Lithium ion (Li-ion) batteries, or secondary batteries, are rechargeable and used world-wide. A lithium-ion battery is used for applications that require recharge capability. Lithium ion batteries provide high energy density, though lower than lithium primary, and can be recharged time after time. These batteries contain no free lithium metal, but do contain lithium ions and highly flammable electrolytes. Common applications that incorporate li-ion technology include laptops, cell phones, electric vehicles, hospital equipment, and energy storage systems, to name a few.
The growth of the lithium battery market
Risk managers might note that the current global market for lithium ion batteries is near $11.7 billion for 2012 (Frost and Sullivan). Risk managers might also note that the same Frost and Sullivan report expects this number to double by 2016. Yes, double in four years! These batteries are found in nearly every power requiring application. Airports see thousands of batteries go through their gates each day. Hospitals utilize battery power in more and more systems; from rechargeable gurneys to critical monitoring systems. Colleges and universities have them on campuses in huge amounts (i.e. laptops and smart devices). Lithium batteries are an integral part of everyday life now, with their use expected to explode as demand grows and manufacturing costs plummet. Their impact is enormous now; what will their impact be a few short years from now?
As the use of lithium batteries grows, so will the fire threat in the entire battery life cycle. Manufacturers, shippers, warehousing, distributors, retailers, and some end users, will have to become more aware of the fire and safety hazards that accompany these powerful tools. Every stop of the battery supply chain is responsible for the safe storage, and handling of the batteries.
Of course, risk managers have a real understanding of the negative impact that the unfortunate fire/explosion incident might have on an organization. It is for this reason that they have shown high interest in learning more about the issues and identifying best practices and methodologies for mitigating, preventing, and responding to battery fire emergencies.
Lithium battery fire behavior
Lithium batteries are capable of spontaneous ignition and subsequent explosion due to overheating. Overheating may be caused by electrical shorting, rapid discharge, overcharging, manufacturers defect, poor design, or mechanical damage, among many other causes. Overheating results in a process called thermal runaway, which is a reaction within the battery causing internal temperature and pressure to rise at a quicker rate then can be dissipated.
Once one battery cell goes into thermal runaway, it produces enough heat to cause adjacent battery cells to also go into thermal runaway. This produces a fire that repeatedly flares up as each battery cell in turn ruptures and releases its contents. The result is the release of flammable electrolyte from the battery and, in the case of disposable lithium batteries, the release of molten burning lithium. An enormous issue is that these fires can’t be treated like “normal” fires and require specific training, planning, storage, and extinguishing interventions.
The amount of data relative to the fire behaviour of large format batteries is limited. However we can predict that when a battery goes into thermal runaway, the propagation creates identifiable markers; the battery behaves in a certain way. The fire may be a progressive burn-off or one that is explosive in nature. Both of these types of thermal events, as well as their negative by-products (jetted shrapnel, molten metal, burning electrolytes, and other matter), can be managed and contained in the appropriate storage and transport environments.
High-profile lithium battery fire incidents
There have been many high-profile fire/explosion instances that highlight lithium battery fire concerns. The most visible and recent issue has been the fires aboard the Boeing 787 Dreamliner. At the time this article was written, the fire cause was yet to be determined. However, the clear consensus seems to be that the fire (Boston fire) originated in the lithium ion battery or its battery management system (BMS). Though the fire issues have presented a red flag relative to the use of lithium ion batteries on airliners, the fact is that Boeing was/is pushing the limits on aviation technology development. For this, it seems, the company shouldn’t be indicted. The use of lithium ion or other high-capacity battery systems will only increase in the future as advanced systems will require, and be developed around, the added power capability.
While the fallout from the incident is yet to be decided, it can be inferred that some damage has been done, to the company, to the airline industry, and to the companies involved in the development of the airliners’ battery power systems. The use of power systems that employ lithium ion batteries may require some getting used to and evolution of suppression and containment systems that are focused on mitigating negative failure outcomes thus managing the risk and making it palatable to users.
The extent of lithium ion battery fire incidents does not end with Boeing – by far! Other incidents of notoriety have occurred in battery systems around the globe. The fires have occurred in energy storage systems (wind, solar, etc.), battery test environments, shipping and storage activities, and many other areas. Spontaneous battery pack ignitions have taken place in a number of electric vehicles, many involving fire or explosion. Though many in the automotive, fire-research, and emergency response industries consider the risk of fire in lithium battery-powered vehicles to be no greater than conventional vehicle systems, there is a general recognition that the by-products, heat, and flame created by these fires create uniquely dangerous conditions. These conditions include toxic substances release and volatile burn characteristics. In other words, while lithium battery fires might not be “more” dangerous, they are very different and uniquely dangerous.
Organizations that manufacture, ship, and store lithium batteries haven’t been immune to the fire incident. Thermal runaway events have contributed to a number of large-scale fires in facilities that contained stored lithium batteries. These fires are particularly high-impact as they involve large volumes of batteries stored in configurations that encourage fire spread.
Research and testing
Since the rapid exploitation of lithium batteries into commercial and industrial applications, little data exists relative to storage and fire response guidelines. The NFPA presents the most comprehensive collection of data relative to these issues. The Fire Protection Research Foundation of the NFPA published the Lithium-Ion Batteries Hazard and Use Assessment. This document provides suppressant research data, limited fire test data, and other information relative to fire and safety issues in small-capacity lithium ion batteries. The document serves as a fine place to start when developing a sound understanding of the fire/explosion risk issues associated with lithium batteries.
Ongoing research will eventually present firm protocols relative to the safe storage, fire management, and fire suppression issues of batteries. While movement is slow in this area, those concerned can rest assured that there are organizations willing to expend time and resources towards developing effective solutions. For example, the United States military (particularly the Army and Navy), have invested considerable resources towards tackling the fire/explosion safety issues and preparing their employees for the worst case scenario.
Managing the risks
Lithium battery fire risks can be managed effectively. Proper planning, risk assessment, storage methods, and response protocols can go a long way in managing the fire risks of lithium batteries. The following areas should be addressed when developing strategies for managing battery fire risks.
Storage/transport safety
There is inherent danger associated with the handling of batteries. In most cases, mechanical damage would probably rank as the highest risk factor for initiating a thermal runaway (fire/explosion) event. Improper handling can result in crush or puncture damage possibly leading to the release of electrolyte material or short-circuiting. These actions could result in thermal runaway and a resulting fire and/or explosion.
In the May of this year, FM Global along with NFPA’s Fire Protection Research Foundation released data relative to flammability characteristics of lithium ion batteries in storage. The report, which detailed large-scale fire tests of lithium ion batteries in warehouse storage, represents ground-breaking research into batteries in fire events. The test results seemed to confirm the following:
- Li-ion batteries present several unique fire hazards when involved in a fire, due to an ignitable electrolyte liquid contained within such products.
- Densely packed li-ion cylindrical cells and polymer cells behave differently than li-ion power tool packs in such fires.
- When bulk stored in corrugated board cartons, early fire extinguishment and cooling of the li-ion batteries is imperative to properly protect a facility.
- Existing protection solutions used for other types of high hazard products and materials can be effective for protecting li-ion batteries stored in bulk arrangements.
Though FM Global and the NFPA should be applauded for taking the initiative on this type of fire testing, the test activities had limitations. One of the glaring limitations of the testing activities was that it was limited to small-capacity 18650 cells. These are the kind commonly used in electronic devices (think AA size). Burn testing of higher-capacity batteries, like those found in electric vehicles, energy storage, and other configurations, may be called for as these present far different burn characteristics and outcomes. The fire management challenges presented by larger-capacity batteries shouldn’t be underestimated.
Though the NFPA and other standard writing organizations haven’t yet completed formal standards and guidelines by which to manage the battery fire issue, there are storage and transport strategies that may help manage the risks. Identifying consultants that specialize in lithium battery fire management and suppression is a great place to start. These companies are different from generic fire suppression consultants and distributors as they are well versed in the unique storage and suppression methods and risk management practices germane to lithium battery fire issues.
At minimum, an effective strategy for storing lithium batteries is to develop fire containment and suppression systems that would deal with the battery fire event. Systems like this would contain the fire event and encourage Suppression through Cooling, Isolation, and Containment, or SCIC. A prime consideration in this approach is that batteries are housed in environments that feature fire suppression systems that extinguish through cooling. Suppressing a lithium ion (secondary) battery is best accomplished by cooling the burning material; lithium primaries require separate, and unique, suppression methodologies.
Another consideration is that lithium batteries should be isolated from other battery chemistries and commodities (storage, transport, etc.). They should be stored (shipped) in environments that would effectively contain fires and toxic burn by-products. This is essential to health, safety, and preservation of property. Close attention should be paid to isolating batteries from general facilities by developing external storage or “satellite” storage. Battery storage farms would allow for storage off-site with just-in-time (JIT) delivery of batteries to the organization when needed.
Training
Since lithium batteries present critical challenges to organizations that possess them, it is recommended that training be included in any risk management strategy. As mentioned, batteries are part of nearly every function of business and personal life; they surround nearly everyone at all times. As a result, organizations and individuals alike should be aware of the unique hazards that these batteries bring to bear. Companies that possess lithium batteries in high volumes should work with experts to develop training that seeks to mitigate the fire issues and ensures additional layers of safety. Training might address issues like battery awareness or might include more detailed situational training such as battery fire behavior, emergency response procedures, and fire extinguisher use (lithium ion battery focus). This type of training lends itself well to the preservation of life and property.
Standard operating procedures
Effective battery standard operating procedures (SOP’s) will include processes that guide shipping and receiving, handling, daily use, storage, and other functions involving the batteries. Proper SOP’s will address every facet of the battery life cycle. These procedures provide the basis for safe use and manipulation and the starting point for developing effective risk management processes.
Emergency response procedures
In most instances, lithium battery fires shouldn’t necessarily be treated like common fires. The burn characteristics and toxic by-product release components are simply different. An organization might determine their level of risk through proper assessment, and create emergency response procedures based on sound response and battery handling data. Close attention should be paid to MSDS sheets and other suggestions from manufacturers and distributors. These documents prescribe possible methodologies for proper storage, handling, and emergency response. A caveat is that MSDS recommendations vary widely and at times are quite different, ultimately adding to some confusion.
However, some of the suggestions are quite good and can be used to develop a strong battery management process.
Where does risk management go from here?
It is clear that lithium battery technology, though great as a tool, has a downside. What is less clear is the path that needs to be taken to properly limit the fire/explosion risks and effectively shrink the downside. Proper planning, storage, and training can result in the development of robust battery management processes. Paying attention to the fire and explosion issues can go a long way in protecting valuable lives and property from these risks.
*For more information go to http://www.hemmingfire.com