Mobile phones, cameras, computers, tools, cars—everyday life is increasingly powered by lithium batteries, and with good reason. Lithium makes for great portable power—it's extremely light, and produces the greatest amount of energy by weight.
There are other advantages. Unlike nickel-cadmium rechargeables, lithium batteries don't have to be completely discharged periodically in order to prolong their useful life. As well, although lithium batteries should be recycled, they do pose less hazard to the environment—cadmium is a toxic metal that must not be disposed of in landfills.
But no new technology is without its own risks. With public safety top of mind, Transport Canada is working with researchers at the National Research Council of Canada to better understand risks posed by battery damage as well as design and manufacturing defects.
What are the risks?
Lithium batteries can catch fire because, as National Research Council Senior Researcher Dr. Khalid Fatih explains, they contain the three elements needed to create fire—combustible materials, electrical energy to provide ignition, and oxides that provide the oxygen needed to enable combustion.
Counterfeit and no-brand lithium batteries are a particular concern—they may be poorly designed, have manufacturing defects, and may not have been safety tested.
"At the same time, even well-designed and manufactured lithium batteries may be sensitive to the kind of abuse that can happen during shipping," says Dr. Fatih. "They can be subjected to very high shocks if they are bumped around and, when shipped by air, they will be subjected to pressure changes, extreme and rapid temperature changes and other stresses. Any of these can damage the batteries, leading to overheating and fire."
Because of the risk of fire—a particular danger when shipped by air—lithium batteries are considered "dangerous goods", and are subject to the rules and regulations set out in Canada's Transportation of Dangerous Goods Act, as well as regulations set by the United Nations.
Among others, lithium batteries must be tested by the manufacturer before shipping to ensure they will stand up to a certain amount of abuse. The regulations also cover how the batteries are packaged, including clear labelling to let carriers know they are handling lithium batteries.
Dr. Fatih, Team Leader in the Electrochemical Components and Systems Engineering section of NRC's Energy, Mining and Environment portfolio, says the current regulations are good, but they could be better.
Gathering the evidence
"The existing regulations are updated on an ongoing basis, but there are some areas of concern," says Dr. Fatih, "In many cases, a regulation is based on expert opinion that is in turn based on experience with other types of batteries—rather than on experimental data with lithium batteries."
To help inform future refinement and fill gaps in the existing regulations, Dr. Fatih and his team are collecting detailed information on the conditions to which lithium batteries are subjected during shipping. With this information, the researchers will look at ways to mitigate the risks identified in different segments of the supply chain.
The "drop test" is just one example. "In this test, a package of lithium batteries is dropped from a height of 1.2 metres, in any orientation. Provided the batteries aren't damaged, don't come into contact with one another, don't fall out of the package—and don't catch fire—it passes," says Dr. Fatih. "We have learned from other studies involving different goods, that packages are often dropped as much as 1.8 metres during shipping—so that is a regulation that could be revisited."
The NRC researchers are also collecting detailed data on other stresses to which the batteries can be subjected, especially when shipped by air. "Temperatures on the tarmac while the cargo is being loaded can be very high, and the temperature can drop very rapidly as the aircraft departs and gets to cruising altitude. During the transportation cycle there's often high humidity, as well as changes in pressure and other conditions.
"We also have to consider the complete air transportation cycle—handling and ground transportation, sorting facilities where the cargo is subjected to vibration as well as big drops from conveyors—not just in-flight conditions. We want to know exactly what those stresses are, how they can impact the integrity of the batteries, and what can be done to mitigate those kinds of stresses and reduce the risk of on-board fires."
The human factor
Dr. Fatih's study also examines the human factors that can have an effect on the safety of lithium batteries during shipping. Among others, Dr. Fatih says some manufacturers may take advantage of loopholes in the regulations, by not declaring the total energy density of the batteries in a package, exempting them from certain safety requirements. Others may not declare that the package contains lithium batteries at all.
"Appropriate, standardized procedures for safe handling and transportation are required to avoid serious incidents," says Dr. Fatih. "However, many of the existing requirements are difficult to monitor for compliance, so we have been looking at that aspect of the issue as well.
"Demand for lithium batteries will continue to grow. We want to make sure they get where they're going safely."