Burn yes. Pop yes, but not the sort of explosion necessary to damage an aircraft. That guy on youtube making "grenades" from batteries ... they are more firecracker than weapon. You could do more damage with a bottle of vodka and a match.
Spectacular light show, a good burn... yeah. Thats about it though... It wouldn't be worth a terrorists time... it would just be a light show and a smoke show, could start a fire, which would be bad, but honestly fires get suppressed pretty quick on modern airliners as long as they aren't started in the cargo area and ember for a while... in the end, any attack carried out with a LiPo/LiIon would just be an inconvenience...