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Seven things you need to know about lithium-ion battery safety

09, Tháng 06, 2023
Chia sẻ

Ithium-ion batteries are widely used because they can store large amounts of energy in a relatively small area.
However, they are also prone to potentially catastrophic fire events.

Lithium-ion batteries are the most popular portable energy storage solution, but there are growing concerns about their safety.

Data collated from state fire facilities indicates that more than 450 fires across Australia were related to lithium-ion batteries in the past 18 months and the Australian Competition and Consumer Commission (ACCC) recently published an article calling for input on how to improve battery safety.

Lithium-ion batteries are used in a wide variety of hardware, from electric vehicles and electric motorcycles to mobile phones and laptops. Residential solar systems also use this technology, all the way to grid-scale energy storage systems.

Unfortunately, as even Fire and Rescue NSW admits, not enough is known about the probability of failure of lithium-ion batteries, their failure mechanism and the potential consequences of failure.

We spoke with UNSW expert Dr. Matthew Priestley from the Energy Systems Research Group in the School of Electrical and Telecommunications Engineering, to explore the safety concerns associated with lithium-ion batteries.

"What we're worried about at the moment is the fact that there's very little regulation regarding lithium-ion batteries and the safety aspect involved with that," Dr Priestley said.

"We want and need these energy storage technologies to be safe because they are so important in absorbing renewable energy and it's important that the public and industry don't perceive it as dangerous.

But currently, most people don't fully understand the risks associated with these batteries, or respect them enough. That applies to consumers in their homes, but perhaps even more importantly for professionals using lithium-ion batteries on a larger scale in their workplace.

"I don't think there's enough education about the proper use, storage, recycling or disposal of lithium-ion batteries, and that's the key to moving forward."

Dr. Priestley is the lead scholar on a project that will develop a short course aimed at educating traders, the public and other key stakeholders about the risks associated with high-energy battery systems.

And here he helps explain the key issues and potential solutions related to lithium-ion battery safety.

What devices are being powered by lithium-ion batteries?
Lithium-ion batteries are extremely common in most Australian homes. Mobile phones, laptops, and smart wearables are all powered by lithium-ion batteries, as are newer e-mobility products such as e-bikes and e-scooters.

Power tools can also run on lithium-ion batteries, and they are common in various commercial industries, as well as camping and gardening equipment.

Electric vehicles, such as Teslas, use lithium-ion batteries - as does the same company's Powerwall system that stores energy obtained from rooftop solar panels or the grid.

On a much larger scale, the largest lithium-ion battery in Australia was activated in 2021 at Moorabool Terminal just outside Geelong. Known as the Victorian Big Battery, the 300 megawatt battery can store enough energy to power more than a million homes for 30 minutes.

What are the problems with lithium-ion batteries?
All batteries are potentially hazardous and may pose a safety risk. The difference with lithium-ion batteries available on the market today is that they typically contain a liquid electrolyte with a lithium salt dissolved in a solvent, such as ethylene carbonate, to produce lithium ions.

It is the presence of these lithium ions that gives outstanding battery performance, allowing the battery to store large amounts of energy in a relatively small area, which is why these batteries are so useful and popular. variable.

However, these liquid electrolytes containing lithium ions are highly volatile and flammable, creating a serious fire and explosion hazard, especially when exposed to high temperatures.

Plus, the way lithium-ion batteries generate power also generates heat as a by-product.

In the event of an uncontrolled battery failure, all that energy and heat increases the fuel hazard risk of a potential fire. Heat from lithium-ion battery failures can reach 400 degrees Celsius in just a few seconds, with the highest burning temperature well above this.

Unfortunately, lithium-ion battery fires are also not easy to contain and sustain, which is why they are considered more volatile than other types of batteries.

What causes lithium-ion batteries to fail?
Overheating is one of the main causes of lithium-ion battery failure, although physical damage to the battery can also lead to problems.

Excessive heat — from using a faulty charger and overcharging the battery, for example, or from a short circuit — can damage the internal battery cells and cause the battery to fail.

The main problem with lithium-ion batteries overheating is a phenomenon known as thermal runaway.

In the process, extreme heat spurs the chemical reaction that makes the battery work, thus creating more heat and more chemical reactions than ever before in a catastrophic spiral.

Physical damage to lithium-ion battery cells can allow the electrolyte inside to leak, which is another potentially dangerous hazard.

Why is lithium-ion battery failure so dangerous?
Thermal runaway means that lithium-ion battery fires are extremely difficult to extinguish.

A water-based fire extinguisher will cool the battery to help prevent the spread of fire but will not extinguish the fire on the battery until its energy has been dissipated.

Special lithium-ion gel extinguishers do exist but are not yet widely available for all lithium-ion battery applications. And even if a lithium-ion battery fire appears to have been extinguished, it can flare up hours — or sometimes even days — later.

Lithium-ion batteries can also release highly toxic gases when they fail, and extreme heat can also cause them to explode.

How can people minimize problems with lithium-ion batteries?
Proper use and storage of lithium-ion batteries is extremely important.

Batteries should not be exposed to high external temperatures, for example in direct sunlight for long periods of time.

Overcharging is another fundamental problem as this can generate excessive heat inside the battery cell.

Therefore, it is important to always use a reputable brand charger, rather than the cheap generic version that may be available online.

A good quality charger, designed specifically for the battery you're using, controls how much charge goes into the cell and turns off when fully charged to ensure the system doesn't overheat.

Use extreme caution if the lithium-ion battery suffers any physical damage, such as being dropped or struck by an object, as this can lead to leaks and potential problems.

In an industrial setting, safe battery storage can be critical so that in the event of unexpected failure a fire can be more easily contained and controlled and not spread — this can be quickly quickly lead to dire consequences.

Second-hand lithium-ion batteries should not be purchased online or from unknown and potentially unregulated suppliers.

Why don't we just use other types of batteries?
Other types of rechargeable batteries exist and are widely used — such as nickel-cadmium and even lead-acid dating back to the 19th century.

However, lithium-ion batteries are more useful and therefore much more popular because they combine fast charging, long charge retention and high energy density, for longer battery life in a smaller package.

It is possible that future research will produce another type of battery with the same properties and with less danger than existing lithium-ion technology — such as the solid-state electrolyte batteries that are currently very expensive to produce.

What needs to be done to make lithium-ion batteries safer?
Lithium-ion battery packs feature a battery management system (BMS) designed to protect the battery cells and prevent problems from occurring.

The BMS monitors data including temperature, cell voltage, cell current and cell charge to help ensure that each part of the battery operates correctly and safely. Cooling provisions can also be linked to the BMS to reduce the battery pack temperature if it overheats.

However, it is important that any battery management system be monitored to ensure it is functioning correctly, as failure of the BMS can indirectly lead to failure of the lithium-ion battery itself. In addition, many smaller lithium-ion applications do not have a BMS because it is not cost effective to do so.

Additional education and training, especially for traders, can also help increase knowledge and understanding of the dangers of lithium-ion batteries and help reduce risks and eliminate hazards as much as possible. Good.

Additional research and development will also address some fundamental questions regarding lithium-ion battery safety, although this can be expensive and time consuming.

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