The powergeneratingelement is usedin such a state that the battery element is externallywrappedby a laminatedfilmor the battery element is storedinthe external case.
Small flames were noted in one of the two incidents reported when gases escaping from the battery were ignited by an electrical short-circuit in the presence of ambient oxygen, but that was all external to the batterycase.
Of course, there is still quite a bit of work to be done to make this work: iPhones do not have removable batteries, nor do they support multi-tasking, meaning that some sort of ruggedized, battery-powered externalcase would be necessary to get this battle-ready -- as well some jailbreaking.