Looking for ways to make lithium-ion batteries safer? Well, don’t go to a battery safety conference, because you won’t learn much! At least I didn’t when I went to Cambridge EnerTech’s battery safety event last week in Arlington.
There’s a lot of interesting science around in terms of working out what happens when you short circuit a lithium-ion battery on a very expensive high energy X-ray source (the images are fantastic) but how that helps you, the manufacturer, prevent whatever that “natural” causative agent might be for this to happen seems about as likely as predicting the next self-styled lunatic with enough money (and guns) to carry out a massacre in the USA.
It can’t be done.
As the Donald said: “This is not a guns issue.” And as to battery fires and failures, perhaps they are not a lithium-ion issue. If we didn’t have so many portable devices and electric vehicles, this would not be an issue at all… Of course, you’d have to plug your not-so-smart phone into a wall socket each time you wanted to check your mail and we’d all be connected ‘wiredly’ to do so much that we now take for granted. Or fire granted?
And this brings me to my final topic for this excuse for conference spleen venting… battery stand-up comedy!
It’s a new comedy form that is being developed by Joseph Nowikowski, almost the last act on the two-day event. Nowikowski, a fire investigator, managed to achieve laughs from fire scenes— before and after. Radio-controlled cars bursting into flames, caught on camera (security) in ‘man caves' all over the Union, dog teeth marks on a punctured battery found under a burned out sofa (we kid you not), not to mention the litany of stories of exploding vaping devices (missing teeth thrown in for more good measure) and laptops left charging on beds. All down to lithium-ion.
Nowikowski was right on the money. Sure, the insurance companies will pay out on the fire because they allow for peoples’ stupidity… but if they can show a defective battery was to blame, they’ll be after you. Another investigator in the audience said they had 120 open files on fires, with lithium batteries ‘in the firing line’, so to speak.
Nowikowski didn’t quite say, “if you can charge it, don’t leave it unattended”, but if I had felt like misrepresenting him, I could have sold that story to the so-called British newspaper, The Sun.
Joe public has no idea about the number of fake phone chargers there are in circulation, nor can they tell if a product has a BMS capable of detecting overcharge or thermal runaway in its earliest phase. They have no knowledge of UL and Interek’s safety standards and they like to buy cheap and nasty electronic products (‘cos they’re cheap!).
One day, the catalogue of errors that are ‘crap cells’ with flammable electrolytes will turn into the perfect storm and somewhere, perhaps, a lot of people will die, just like they did in London (thanks to flammable building materials) this summer. For other chemistries, it’s the equivalent of Weinstein’s alleged sex misdemeanours.
Isn’t it time you guys named and shamed?
Volvo has created a way to integrate batteries and supercapacitors into the materials of a car so entire bodywork panels would become a battery.
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Underwriters Laboratory has developed a method of spotting internal short circuits in lithium-ion cells to improve standards relating to the batteries. Such a condition may have caused the notorious Boeing battery Dreamliner fires.
The Indentation Induced test is, according to Underwriter Laboratory (UL), a simple and repeatable way to induce internal short circuits to study battery behaviors when an internal short occurs.
UL says this approach is more rigorous than previous short circuit testing such as by nail penetration and will test cell’s reactions to a mechanical failure. While this is appropriate for impacts on the battery, such as vehicle crashes, it will still not be able to detect or protect cells against internal short circuits that occur due to causes other than mechanical means. It does test a cell for cathode dendritic growth, which many internal short circuits are attributed to.
In the Sustainable Energy Journal from the UL, the report titled ‘Lithium-ion Batteries. stated: “The Indentation Induced internal short circuit test was developed based on best-practice principles to provide a practical and simple method that is very suitable for battery safety standards. This test gives UL the ability to simulate how a lithium-ion cell behaves when subjected to an internal short circuit condition, which will help mitigate the hazards of ISCs and support the safe commercialisation of lithium-ion batteries.”
For the test, a cell is placed in a holder to prevent movement, an indenter presses the cell casing from above at a constant speed of 0.01 – 0.001mm/s. The test is suitable for cylindrical, pouch and prismatic cells at different states of charge or stages of aging and takes place in a temperature controlled chamber. As the indenter presses against the casing, the layers of anode, cathode and separators are deformed below the point of indentation. This heavy strain leads to a mechanical failure of the separator, which causes the electrodes to touch. This causes a drop in the open circuit voltage followed by a rapid increase in the cell’s surface temperature – up to 700oC –, which results in an explosive release of gases and fire.
The criteria for the test were: it must be able to generate a localised internal short circuit within a closed cell that would simulate the conditions similar to those found in the field failures of lithium-ion batteries; secondly it must be acceptable for battery safety standards. UL has partnered with NASA and Oak Ridge National Laboratories to develop test approaches.