Smart Batteries as a fundamental need in Safety-critical applications

Smart Batteries as a fundamental need in Safety-critical applications

Energy CIO Insights | Friday, July 30, 2021

There are several serious issues around rechargeable batteries when it comes to cycle life, charging time, energy waste, overall shelf life, etc., however, first and foremost, the biggest issue to pay attention to, is that these batteries are vastly used in safety-critical applications. This is a dangerous-to-ignore fact!

According to an FAA report, as of April 30, 2021, there have been 312 air/airport incidents involving lithium batteries since January 23, 2006. The LiBs are also largely integrated into general consumer goods like Smart Watches, Laptops, Scooters, etc., and one of the most rapidly commercializing one - the Electric Vehicles

Lately, in the Electric Vehicle market, the LiB integration has been enormous.

In 2020, 3.24 million EV units were produced which is a 43% increase from 2019. This growth rate is not predicted to stop either, with forecasts of the units of EV sales increasing to 500 million by 2040 and accounting for 35% of all new car sales.

In this growth, the lithium-ion batteries for the EVs can both be a large advantage and just as large of an issue too. EVs today have “wet” lithium-ion batteries, based on liquid electrolytes, to shuttle energy around. The LIBs used in EVs usually have slow charge time, contain flammable material, which presents the risks of fire and explosion during and/or after a crash. And range eventually becomes a problem because as batteries age, the range decreases.

Moreover, according to the US fire administration, there are three key safety risks for lithium- ion batteries, as such:

1. Thermal runaway

2. Stranded energy

3. Battery reignition

*A high ignition temperature is still much lower than flame temperatures which can get higher than 1200 °C. Water and foam may cause quick and harsh flames as the water molecules start to separate into explosive gases(hydrogen/oxygen)*.

Lithium-ion battery limitations have been rather clearly understood, yet, those reasons are still hard to determine. In other words, what are the actual bits and pieces that cause the thermal issues in lithium-ion batteries?

To put it simply - after certain performance limits, the positive feedback produced by the hotter cells in Lithium-ion batteries generates more current (and therefore more heat). On top of this, because all currents must pass through each individual cell(the cells are designed to be connected in parallel), uneven cooling can inflame inherent temperature gradients even more. Thereafter, one of the most severe possible results is the thermal runaway, which can be accompanied by flames, explosions, fire, etc.

It is of course important to know that in case of coming across an EV that has caught on fire there are several common risks for first responders:

● Electrical shock (up to 400 volts).

● Extremely high temperatures and thermal runaway.

● Lithium burns (respiratory and skin reactions).

● Toxic fumes and toxic runoff

● Battery reignition (usually up to 24 hours after initial extinguishment

Although it is extremely important to be ready to react to an extreme situation like the ones mentioned above, it is not any less important to develop strategies to prevent or at least minimize these risks.

There have been different approaches developed to deal with this issue - thermal management modeling, air/liquid cooling systems for the LiBs, specific user manuals for individual batteries(to prevent the end-user from i.e overcharging), however, none have proven to be effective enough to attract sufficient attention, and become a proper system that once and for all helps overcome thermal risks with the Lithium-ion batteries.

Economically, a big part of the situation is that making batteries better, smarter, in other words, self-monitored - would mean making them bigger, bulkier, difficult to fit into already-existing production lines, overall more expensive(or simply not accepted by the target markets).

Being the sole manufacturer of the smallest passive sensors in the world - RVmagnettics addresses these issues with the safest, fairly inexpensive solution imaginable.

The sensor in question is called MicroWire. It is a miniaturized passive element, thin and elastic like human hair. Inherently, it is a metallic alloy with a glass coating, however, this perfectly simple and tiny element can provide real-time measurements on temperature, pressure, magnetic field, and indirectly - el. current, flow, stress, etc.

By itself, it doesn’t need any wiring as it is passive and reflects signals only when excited by the sensing system, which does not need to be in contact with the wire(there can be up to 10cms distance between the wire and the sensing system). This of course means that the MicroWire, being resistant to the chemically aggressive environments, can be placed directly inside the battery without causing ignition risks or any significant changes on the design.

The signal from MicroWire is gathered through a sensing system. The technology is able to provide measurements of up to 10.000x/second, thus enabling precise measurements in real-time. Continuous measurements enable Predictive Maintenance, thus bringing the opportunity of Smart Batteries.

There is a common understanding that many modern Battery Powered customer goods are already smart. Especially in the case of the EVs. These are rich with IoT solutions making the user experience and comfort an absolute priority. Although understanding the importance of the User Experience and comfort - safety comes first, and a smart battery in an EV essentially equals a safe driver.

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