Galaxy Note 7 battery chemistry could be behind recall, says expert

Metal impurities or a change in the electrolyte system could be what's causing Galaxy Note 7 batteries to explode, forcing Samsung to issue a global recall of its newest smartphone, according to an expert.

"There are a number of things that can go wrong with high energy density lithium-ion cells that are operated at higher voltages being used in modern phones," said Dalhousie University professor Jeff Dahn.

He is a pioneer in the development of the lithium-ion batteries used in cellphones and automobiles.

• Samsung stops making Galaxy Note 7s as more ignite 
• Samsung issues fireproof boxes to return Galaxy Note 7s 
• Ottawa man says he'll keep using Samsung Galaxy Note 7 despite fire risk

Dahn said if there are metal impurities in the positive electrode, they can dissolve and create internal short circuits in the cell. If Samsung has changed the electrolyte system, that could also lead to problems, he added. 

It's not that Samsung has reached the limit of what it can do with lithium-ion batteries, said Dahn. In fact, he said the lithium-ion hasn't been used to its full potential. 

"Other lithium-ion cells used by, for example Apple, have similar characteristics to the Samsung cells, but they're clearly not having the same issues. So I think there's just something weird with the chemistry in those new Note 7 cells." 

Dahn said lithium-ion batteries are perfectly safe, and it's unusual Samsung is having this problem.

"There's billions and billions and billions of lithium-ion cells in use across the world, and the vast majority are perfectly safe without any issues," he said. 

Dahn noted that any lithium-ion batteries released for consumers have to go through a "huge number" of safety tests in order to be certified for use.