Slashdot Mirror
Smart Battery Tells You When It's About To Explode
sciencehabit writes Material scientists have found a clever way to alert users of damaged batteries before any hazard occurs. A typical lithium-ion cell consists of a lithium oxide cathode and a graphite anode, separated by a thin, porous polymer sheet that allows ions to travel between the electrodes. When the cell is overcharged, microscopic chains of lithium, called "dendrites," sprout from the anode and pierce through the polymer separator until they touch the cathode. An electrical current passing through the dendrites to the cathode can short-circuit the cell, which causes overheating and, in some cases, fire. Attempts to stop dendrite formation have met with limited success, so the researchers tried something different. They built a "smart" separator by sandwiching a 50-nanometer thin copper layer between two polymer sheets and connecting the copper layer to a third electrode for voltage measurement. When the dendrites reach the separator, the voltage between the anode and the copper layer drops to zero, alerting users that they should change the damaged battery while it is still operating safely—disaster averted.
via ticking sound, and a countdown timer. It's expected to be a big hit.
Alerting the user to change the damaged battery makes sense. Now we need to convince the manufacturers to design devices which would make this possible.
I was wondering the same. If the battery can warn that it is about to be compromised to explode, it should also be able to disconnect itself and slowly discharge through a resistor so that it doesn't explode. Many LiIon batteries already have an IC at one end that disconnects it when it is overdischarged or if the discharge rate is too high. If they want to get fancy, that slow discharge could be through a red LED to visibly indicate failure.
Curent generation smart batteries have several systems im place to alert the user to a potentially hazardous or explosive condition in the battery.
smoke: Smart batteries emit choking, acrid fumes to quickly notify users of a problem
warmth: most smart batteries, in order to protect the user, become extremely hot when they encounter a problem. this prevents the user from touching them and in turn, functions as intended to protect the user.
deafening bang: this system, in the event of an explosion condition, emits an extraordinary noise to alert the user. its a technological signal that says, "there is a problem with the battery"
bright flash: Regular batteries have had this ability for a while, but smart batteries utilized an advanced system of both arc flash and visible flames to alert the user of a problem.
toxic shrapnel: is a fast, immediate way of determining when a battery might be about to, or is in the process of exploding. In addition, difficult or impossible to heal wounds from rare earth metals allow the user to retrospectively verify the quality of a particular brand of battery in the future.
Good people go to bed earlier.
http://www.liveleak.com/view?i...
User was installing a new battery that failed due to shorting when installed.
Another story of it happening and photo of the aftermath
http://miami.cbslocal.com/2014...
Different incident. User dropped the phone and the physical damage caused the battery short.
The typical failure mode from dendrite formation is the battery slowly drains itself from the high resistance connection between the cathode and anode that forms, and not a thermal runaway but it can happen. This is a common failure mode for NiCad batteries, but Lithium batteries are much more heat sensitive and the electrolyte when heated too much can release oxygen to fuel a runaway reaction. Battery failures in portable electronics are typically due to physical damage or poor quality chinese made batteries, especially when they omit the protection circuits.
A excellent short primer on Lithium Ion battery failures. Prompted by the recent airline industry incidents.
http://www.ntsb.gov/news/event...