This was a cartoon that had 3 kids, 2 boys and a girl, that used to be on a spaceship. Then there were alarms that there was that substance that they would go and scan with their phone-like devices and then they can turn into monster from that device and fight other people. The name of one the main characters was Kai, and I am pretty sure his name was a part of the name of the show.
Another option could be Redakai: Conquer the Kairu
According to its Wikipedia article, the series was a Canadian/French animated series that premiered on YTV in Canada on July 9, 2011, on Cartoon Network in the United States on July 16, 2011 and on Canal J and Gulli in France on October 22, 2011.
The series revolves around Ky, a 15-year-old student of ancient martial arts, who embarks on an epic quest to find the Kairu, a primordial alien energy source. Aided by his friends Maya and Boomer, Ky travels the world searching for the Kairu while attempting to make sure that his extraterrestrial teenage alien adversaries don’t find it first.
(EDIT: Kudos to Bavnqta on this answer for giving me a tip-off it might be this)