Fire-prone Samsung phone relies on technology used in energy storage

Source: Umair Irfan, E&E reporter • Posted: Friday, October 14, 2016

For a few months, Samsung Electronics literally had the hottest smartphone on the market.

The Galaxy Note7, unveiled in August, met an ignominious death Tuesday as the manufacturer ended production of the phone amid more than 100 reported fires and failures around the world.

The company last month began recalling 2.5 million units of the Note7 “due to a battery cell issue,” the company wrote in an announcement.

But even the replacement devices suffered problems. One replacement began spewing smoke, forcing passengers to evacuate a Southwest Airlines flight parked at the gate in Louisville, Ky., last week, according to The Verge.

In a press release Tuesday, the manufacturer asked retailers to stop selling the phone.

Samsung said that it’s still investigating the root cause of the smoke and fire, but much of the hazard came from the energy stored in the phone’s lithium-ion battery, which ordinarily powered its 5.7-inch screen and quad-core processor.

Lithium-ion batteries are rechargeable and can store lots of electricity for their weight and size, making them very useful in phones, electric cars and on the power grid. Billions of devices now run on these batteries.

However, packing all that energy into a small space creates problems if it’s not done right, and as these batteries become more powerful and more numerous, engineers are racing to stay ahead of safety concerns that could dampen the public’s faith in these technologies.

“It’s been a very busy time for us in the battery safety space,” said Ken Boyce, principal engineer director in energy and power technologies at UL, a consumer product safety testing and certification firm.

He noted that the lithium-ion battery chemistry has been on the market since 1990 and has performed well, with a roughly 1-in-10-million failure rate. But each year, manufacturers make more than 6 billion cells.

“That’s hundreds of incidents each year,” Boyce said.

In addition, customers want their phones to run all day and want electric cars to travel farther with each charge, so manufacturers are scaling up the energy density in batteries. “Even within lithium-ion, we’re seeing the industry moving toward packing more material into the battery and reducing the separator thickness [between electrodes],” Boyce said.

The big concern with lithium-ion batteries is a condition called a thermal runaway, a feedback loop where rising temperatures in a cell cause it to destroy itself and further increase its temperature. This is typically triggered at temperatures above 150 degrees Celsius.

George Crabtree, director of the Department of Energy’s Joint Center for Energy Storage Research, explained that there are four common ways to trigger a thermal runaway in a lithium-ion cell.

An object can physically puncture the cell and short it out. A manufacturing defect can also lead to a short circuit that makes the battery heat up. Charging the battery too fast can cause the lithium ions to plate on the anode, creating fingerlike projections called dendrites that can breach the cell’s membrane and touch the cathode. Overcharging the battery above its capacity can also cause it to overheat enough to cause a runaway.

In the case of the Note7, Crabtree said, the problem isn’t with the lithium-ion chemistry itself. “It seems to indicate that there’s a defect in the battery or phone,” he said.

Researchers are now developing battery chemistries that don’t have to deal with thermal runaway issues while storing more energy (ClimateWire, Oct. 30, 2015).

“This thermal runaway is not part of the energy storing or releasing process. It’s a side reaction,” Crabtree said. “There’s a very hopeful way out of this.”

Boeing and Tesla use lithium-ion

In the meantime, lithium-ion is likely to remain the king of energy storage and expand its kingdom as companies like Tesla work to make batteries a common household appliance alongside its electric cars.

Batteries in these roles consist of dozens of smaller lithium-ion cells in packs that store much more electricity than mobile phones, so the potential harm from a thermal runaway is much greater. On the other hand, large battery packs mean that a single failing cell doesn’t have to take out the entire system, and with sophisticated power management systems, vehicle, household and grid batteries can be made even safer.

“Those sort of systems-level safety elements are just not available for a single battery in a cellphone,” said Tim Grejtak, an analyst at Lux Research.

Grid-level energy storage capacity is poised to increase a hundredfold from 2013 levels by 2022, and lithium-ion manufacturing is poised to triple (ClimateWire, Feb. 27, 2015).

But if manufacturers don’t get it right, it could be devastating for them, with costly recalls and loss of consumer confidence in fledgling clean-energy technologies.

Nokia recalled 46 million batteries in its cellphones due to fire and explosion risks in 2007, one of the largest recalls ever. The company has struggled to regain its market share since.

Fires in the lithium-ion batteries in Boeing’s fuel-efficient 787 Dreamliner jet led to a worldwide grounding of the fleet and cost the company more than $600 million (ClimateWire, Dec. 18, 2014).

Samsung’s recall announcement led to shares dropping 8 percent this week, cutting the company’s market capitalization by $17 billion.

“These new products are trying to solve all problems at once, and that’s just very difficult,” Grejtak said. “It’s a lot of pressure on this new market, and we can only ask for patience.”